btcd: github.com/btcsuite/btcd/txscript Index | Examples | Files

package txscript

import "github.com/btcsuite/btcd/txscript"

Package txscript implements the bitcoin transaction script language.

A complete description of the script language used by bitcoin can be found at https://en.bitcoin.it/wiki/Script. The following only serves as a quick overview to provide information on how to use the package.

This package provides data structures and functions to parse and execute bitcoin transaction scripts.

Script Overview

Bitcoin transaction scripts are written in a stack-base, FORTH-like language.

The bitcoin script language consists of a number of opcodes which fall into several categories such pushing and popping data to and from the stack, performing basic and bitwise arithmetic, conditional branching, comparing hashes, and checking cryptographic signatures. Scripts are processed from left to right and intentionally do not provide loops.

The vast majority of Bitcoin scripts at the time of this writing are of several standard forms which consist of a spender providing a public key and a signature which proves the spender owns the associated private key. This information is used to prove the the spender is authorized to perform the transaction.

One benefit of using a scripting language is added flexibility in specifying what conditions must be met in order to spend bitcoins.

Errors

Errors returned by this package are of type txscript.Error. This allows the caller to programmatically determine the specific error by examining the ErrorCode field of the type asserted txscript.Error while still providing rich error messages with contextual information. A convenience function named IsErrorCode is also provided to allow callers to easily check for a specific error code. See ErrorCode in the package documentation for a full list.

Index

Examples

Package Files

consensus.go doc.go engine.go error.go hashcache.go log.go opcode.go pkscript.go script.go scriptbuilder.go scriptnum.go sigcache.go sign.go stack.go standard.go

Constants

const (
    // MaxStackSize is the maximum combined height of stack and alt stack
    // during execution.
    MaxStackSize = 1000

    // MaxScriptSize is the maximum allowed length of a raw script.
    MaxScriptSize = 10000
)
const (
    OP_0                   = 0x00 // 0
    OP_FALSE               = 0x00 // 0 - AKA OP_0
    OP_DATA_1              = 0x01 // 1
    OP_DATA_2              = 0x02 // 2
    OP_DATA_3              = 0x03 // 3
    OP_DATA_4              = 0x04 // 4
    OP_DATA_5              = 0x05 // 5
    OP_DATA_6              = 0x06 // 6
    OP_DATA_7              = 0x07 // 7
    OP_DATA_8              = 0x08 // 8
    OP_DATA_9              = 0x09 // 9
    OP_DATA_10             = 0x0a // 10
    OP_DATA_11             = 0x0b // 11
    OP_DATA_12             = 0x0c // 12
    OP_DATA_13             = 0x0d // 13
    OP_DATA_14             = 0x0e // 14
    OP_DATA_15             = 0x0f // 15
    OP_DATA_16             = 0x10 // 16
    OP_DATA_17             = 0x11 // 17
    OP_DATA_18             = 0x12 // 18
    OP_DATA_19             = 0x13 // 19
    OP_DATA_20             = 0x14 // 20
    OP_DATA_21             = 0x15 // 21
    OP_DATA_22             = 0x16 // 22
    OP_DATA_23             = 0x17 // 23
    OP_DATA_24             = 0x18 // 24
    OP_DATA_25             = 0x19 // 25
    OP_DATA_26             = 0x1a // 26
    OP_DATA_27             = 0x1b // 27
    OP_DATA_28             = 0x1c // 28
    OP_DATA_29             = 0x1d // 29
    OP_DATA_30             = 0x1e // 30
    OP_DATA_31             = 0x1f // 31
    OP_DATA_32             = 0x20 // 32
    OP_DATA_33             = 0x21 // 33
    OP_DATA_34             = 0x22 // 34
    OP_DATA_35             = 0x23 // 35
    OP_DATA_36             = 0x24 // 36
    OP_DATA_37             = 0x25 // 37
    OP_DATA_38             = 0x26 // 38
    OP_DATA_39             = 0x27 // 39
    OP_DATA_40             = 0x28 // 40
    OP_DATA_41             = 0x29 // 41
    OP_DATA_42             = 0x2a // 42
    OP_DATA_43             = 0x2b // 43
    OP_DATA_44             = 0x2c // 44
    OP_DATA_45             = 0x2d // 45
    OP_DATA_46             = 0x2e // 46
    OP_DATA_47             = 0x2f // 47
    OP_DATA_48             = 0x30 // 48
    OP_DATA_49             = 0x31 // 49
    OP_DATA_50             = 0x32 // 50
    OP_DATA_51             = 0x33 // 51
    OP_DATA_52             = 0x34 // 52
    OP_DATA_53             = 0x35 // 53
    OP_DATA_54             = 0x36 // 54
    OP_DATA_55             = 0x37 // 55
    OP_DATA_56             = 0x38 // 56
    OP_DATA_57             = 0x39 // 57
    OP_DATA_58             = 0x3a // 58
    OP_DATA_59             = 0x3b // 59
    OP_DATA_60             = 0x3c // 60
    OP_DATA_61             = 0x3d // 61
    OP_DATA_62             = 0x3e // 62
    OP_DATA_63             = 0x3f // 63
    OP_DATA_64             = 0x40 // 64
    OP_DATA_65             = 0x41 // 65
    OP_DATA_66             = 0x42 // 66
    OP_DATA_67             = 0x43 // 67
    OP_DATA_68             = 0x44 // 68
    OP_DATA_69             = 0x45 // 69
    OP_DATA_70             = 0x46 // 70
    OP_DATA_71             = 0x47 // 71
    OP_DATA_72             = 0x48 // 72
    OP_DATA_73             = 0x49 // 73
    OP_DATA_74             = 0x4a // 74
    OP_DATA_75             = 0x4b // 75
    OP_PUSHDATA1           = 0x4c // 76
    OP_PUSHDATA2           = 0x4d // 77
    OP_PUSHDATA4           = 0x4e // 78
    OP_1NEGATE             = 0x4f // 79
    OP_RESERVED            = 0x50 // 80
    OP_1                   = 0x51 // 81 - AKA OP_TRUE
    OP_TRUE                = 0x51 // 81
    OP_2                   = 0x52 // 82
    OP_3                   = 0x53 // 83
    OP_4                   = 0x54 // 84
    OP_5                   = 0x55 // 85
    OP_6                   = 0x56 // 86
    OP_7                   = 0x57 // 87
    OP_8                   = 0x58 // 88
    OP_9                   = 0x59 // 89
    OP_10                  = 0x5a // 90
    OP_11                  = 0x5b // 91
    OP_12                  = 0x5c // 92
    OP_13                  = 0x5d // 93
    OP_14                  = 0x5e // 94
    OP_15                  = 0x5f // 95
    OP_16                  = 0x60 // 96
    OP_NOP                 = 0x61 // 97
    OP_VER                 = 0x62 // 98
    OP_IF                  = 0x63 // 99
    OP_NOTIF               = 0x64 // 100
    OP_VERIF               = 0x65 // 101
    OP_VERNOTIF            = 0x66 // 102
    OP_ELSE                = 0x67 // 103
    OP_ENDIF               = 0x68 // 104
    OP_VERIFY              = 0x69 // 105
    OP_RETURN              = 0x6a // 106
    OP_TOALTSTACK          = 0x6b // 107
    OP_FROMALTSTACK        = 0x6c // 108
    OP_2DROP               = 0x6d // 109
    OP_2DUP                = 0x6e // 110
    OP_3DUP                = 0x6f // 111
    OP_2OVER               = 0x70 // 112
    OP_2ROT                = 0x71 // 113
    OP_2SWAP               = 0x72 // 114
    OP_IFDUP               = 0x73 // 115
    OP_DEPTH               = 0x74 // 116
    OP_DROP                = 0x75 // 117
    OP_DUP                 = 0x76 // 118
    OP_NIP                 = 0x77 // 119
    OP_OVER                = 0x78 // 120
    OP_PICK                = 0x79 // 121
    OP_ROLL                = 0x7a // 122
    OP_ROT                 = 0x7b // 123
    OP_SWAP                = 0x7c // 124
    OP_TUCK                = 0x7d // 125
    OP_CAT                 = 0x7e // 126
    OP_SUBSTR              = 0x7f // 127
    OP_LEFT                = 0x80 // 128
    OP_RIGHT               = 0x81 // 129
    OP_SIZE                = 0x82 // 130
    OP_INVERT              = 0x83 // 131
    OP_AND                 = 0x84 // 132
    OP_OR                  = 0x85 // 133
    OP_XOR                 = 0x86 // 134
    OP_EQUAL               = 0x87 // 135
    OP_EQUALVERIFY         = 0x88 // 136
    OP_RESERVED1           = 0x89 // 137
    OP_RESERVED2           = 0x8a // 138
    OP_1ADD                = 0x8b // 139
    OP_1SUB                = 0x8c // 140
    OP_2MUL                = 0x8d // 141
    OP_2DIV                = 0x8e // 142
    OP_NEGATE              = 0x8f // 143
    OP_ABS                 = 0x90 // 144
    OP_NOT                 = 0x91 // 145
    OP_0NOTEQUAL           = 0x92 // 146
    OP_ADD                 = 0x93 // 147
    OP_SUB                 = 0x94 // 148
    OP_MUL                 = 0x95 // 149
    OP_DIV                 = 0x96 // 150
    OP_MOD                 = 0x97 // 151
    OP_LSHIFT              = 0x98 // 152
    OP_RSHIFT              = 0x99 // 153
    OP_BOOLAND             = 0x9a // 154
    OP_BOOLOR              = 0x9b // 155
    OP_NUMEQUAL            = 0x9c // 156
    OP_NUMEQUALVERIFY      = 0x9d // 157
    OP_NUMNOTEQUAL         = 0x9e // 158
    OP_LESSTHAN            = 0x9f // 159
    OP_GREATERTHAN         = 0xa0 // 160
    OP_LESSTHANOREQUAL     = 0xa1 // 161
    OP_GREATERTHANOREQUAL  = 0xa2 // 162
    OP_MIN                 = 0xa3 // 163
    OP_MAX                 = 0xa4 // 164
    OP_WITHIN              = 0xa5 // 165
    OP_RIPEMD160           = 0xa6 // 166
    OP_SHA1                = 0xa7 // 167
    OP_SHA256              = 0xa8 // 168
    OP_HASH160             = 0xa9 // 169
    OP_HASH256             = 0xaa // 170
    OP_CODESEPARATOR       = 0xab // 171
    OP_CHECKSIG            = 0xac // 172
    OP_CHECKSIGVERIFY      = 0xad // 173
    OP_CHECKMULTISIG       = 0xae // 174
    OP_CHECKMULTISIGVERIFY = 0xaf // 175
    OP_NOP1                = 0xb0 // 176
    OP_NOP2                = 0xb1 // 177
    OP_CHECKLOCKTIMEVERIFY = 0xb1 // 177 - AKA OP_NOP2
    OP_NOP3                = 0xb2 // 178
    OP_CHECKSEQUENCEVERIFY = 0xb2 // 178 - AKA OP_NOP3
    OP_NOP4                = 0xb3 // 179
    OP_NOP5                = 0xb4 // 180
    OP_NOP6                = 0xb5 // 181
    OP_NOP7                = 0xb6 // 182
    OP_NOP8                = 0xb7 // 183
    OP_NOP9                = 0xb8 // 184
    OP_NOP10               = 0xb9 // 185
    OP_UNKNOWN186          = 0xba // 186
    OP_UNKNOWN187          = 0xbb // 187
    OP_UNKNOWN188          = 0xbc // 188
    OP_UNKNOWN189          = 0xbd // 189
    OP_UNKNOWN190          = 0xbe // 190
    OP_UNKNOWN191          = 0xbf // 191
    OP_UNKNOWN192          = 0xc0 // 192
    OP_UNKNOWN193          = 0xc1 // 193
    OP_UNKNOWN194          = 0xc2 // 194
    OP_UNKNOWN195          = 0xc3 // 195
    OP_UNKNOWN196          = 0xc4 // 196
    OP_UNKNOWN197          = 0xc5 // 197
    OP_UNKNOWN198          = 0xc6 // 198
    OP_UNKNOWN199          = 0xc7 // 199
    OP_UNKNOWN200          = 0xc8 // 200
    OP_UNKNOWN201          = 0xc9 // 201
    OP_UNKNOWN202          = 0xca // 202
    OP_UNKNOWN203          = 0xcb // 203
    OP_UNKNOWN204          = 0xcc // 204
    OP_UNKNOWN205          = 0xcd // 205
    OP_UNKNOWN206          = 0xce // 206
    OP_UNKNOWN207          = 0xcf // 207
    OP_UNKNOWN208          = 0xd0 // 208
    OP_UNKNOWN209          = 0xd1 // 209
    OP_UNKNOWN210          = 0xd2 // 210
    OP_UNKNOWN211          = 0xd3 // 211
    OP_UNKNOWN212          = 0xd4 // 212
    OP_UNKNOWN213          = 0xd5 // 213
    OP_UNKNOWN214          = 0xd6 // 214
    OP_UNKNOWN215          = 0xd7 // 215
    OP_UNKNOWN216          = 0xd8 // 216
    OP_UNKNOWN217          = 0xd9 // 217
    OP_UNKNOWN218          = 0xda // 218
    OP_UNKNOWN219          = 0xdb // 219
    OP_UNKNOWN220          = 0xdc // 220
    OP_UNKNOWN221          = 0xdd // 221
    OP_UNKNOWN222          = 0xde // 222
    OP_UNKNOWN223          = 0xdf // 223
    OP_UNKNOWN224          = 0xe0 // 224
    OP_UNKNOWN225          = 0xe1 // 225
    OP_UNKNOWN226          = 0xe2 // 226
    OP_UNKNOWN227          = 0xe3 // 227
    OP_UNKNOWN228          = 0xe4 // 228
    OP_UNKNOWN229          = 0xe5 // 229
    OP_UNKNOWN230          = 0xe6 // 230
    OP_UNKNOWN231          = 0xe7 // 231
    OP_UNKNOWN232          = 0xe8 // 232
    OP_UNKNOWN233          = 0xe9 // 233
    OP_UNKNOWN234          = 0xea // 234
    OP_UNKNOWN235          = 0xeb // 235
    OP_UNKNOWN236          = 0xec // 236
    OP_UNKNOWN237          = 0xed // 237
    OP_UNKNOWN238          = 0xee // 238
    OP_UNKNOWN239          = 0xef // 239
    OP_UNKNOWN240          = 0xf0 // 240
    OP_UNKNOWN241          = 0xf1 // 241
    OP_UNKNOWN242          = 0xf2 // 242
    OP_UNKNOWN243          = 0xf3 // 243
    OP_UNKNOWN244          = 0xf4 // 244
    OP_UNKNOWN245          = 0xf5 // 245
    OP_UNKNOWN246          = 0xf6 // 246
    OP_UNKNOWN247          = 0xf7 // 247
    OP_UNKNOWN248          = 0xf8 // 248
    OP_UNKNOWN249          = 0xf9 // 249
    OP_SMALLINTEGER        = 0xfa // 250 - bitcoin core internal
    OP_PUBKEYS             = 0xfb // 251 - bitcoin core internal
    OP_UNKNOWN252          = 0xfc // 252
    OP_PUBKEYHASH          = 0xfd // 253 - bitcoin core internal
    OP_PUBKEY              = 0xfe // 254 - bitcoin core internal
    OP_INVALIDOPCODE       = 0xff // 255 - bitcoin core internal
)

These constants are the values of the official opcodes used on the btc wiki, in bitcoin core and in most if not all other references and software related to handling BTC scripts.

const (
    OpCondFalse = 0
    OpCondTrue  = 1
    OpCondSkip  = 2
)

Conditional execution constants.

const (
    MaxOpsPerScript       = 201 // Max number of non-push operations.
    MaxPubKeysPerMultiSig = 20  // Multisig can't have more sigs than this.
    MaxScriptElementSize  = 520 // Max bytes pushable to the stack.
)

These are the constants specified for maximums in individual scripts.

const (
    // MaxDataCarrierSize is the maximum number of bytes allowed in pushed
    // data to be considered a nulldata transaction
    MaxDataCarrierSize = 80

    // StandardVerifyFlags are the script flags which are used when
    // executing transaction scripts to enforce additional checks which
    // are required for the script to be considered standard.  These checks
    // help reduce issues related to transaction malleability as well as
    // allow pay-to-script hash transactions.  Note these flags are
    // different than what is required for the consensus rules in that they
    // are more strict.
    //
    // TODO: This definition does not belong here.  It belongs in a policy
    // package.
    StandardVerifyFlags = ScriptBip16 |
        ScriptVerifyDERSignatures |
        ScriptVerifyStrictEncoding |
        ScriptVerifyMinimalData |
        ScriptStrictMultiSig |
        ScriptDiscourageUpgradableNops |
        ScriptVerifyCleanStack |
        ScriptVerifyNullFail |
        ScriptVerifyCheckLockTimeVerify |
        ScriptVerifyCheckSequenceVerify |
        ScriptVerifyLowS |
        ScriptStrictMultiSig |
        ScriptVerifyWitness |
        ScriptVerifyDiscourageUpgradeableWitnessProgram |
        ScriptVerifyMinimalIf |
        ScriptVerifyWitnessPubKeyType
)
const (
    // LockTimeThreshold is the number below which a lock time is
    // interpreted to be a block number.  Since an average of one block
    // is generated per 10 minutes, this allows blocks for about 9,512
    // years.
    LockTimeThreshold = 5e8 // Tue Nov 5 00:53:20 1985 UTC
)

Variables

var Bip16Activation = time.Unix(1333238400, 0)

Bip16Activation is the timestamp where BIP0016 is valid to use in the blockchain. To be used to determine if BIP0016 should be called for or not. This timestamp corresponds to Sun Apr 1 00:00:00 UTC 2012.

var (
    // ErrUnsupportedScriptType is an error returned when we attempt to
    // parse/re-compute an output script into a PkScript struct.
    ErrUnsupportedScriptType = errors.New("unsupported script type")
)
var OpcodeByName = make(map[string]byte)

OpcodeByName is a map that can be used to lookup an opcode by its human-readable name (OP_CHECKMULTISIG, OP_CHECKSIG, etc).

func CalcMultiSigStats Uses

func CalcMultiSigStats(script []byte) (int, int, error)

CalcMultiSigStats returns the number of public keys and signatures from a multi-signature transaction script. The passed script MUST already be known to be a multi-signature script.

func CalcSignatureHash Uses

func CalcSignatureHash(script []byte, hashType SigHashType, tx *wire.MsgTx, idx int) ([]byte, error)

CalcSignatureHash will, given a script and hash type for the current script engine instance, calculate the signature hash to be used for signing and verification.

func CalcWitnessSigHash Uses

func CalcWitnessSigHash(script []byte, sigHashes *TxSigHashes, hType SigHashType,
    tx *wire.MsgTx, idx int, amt int64) ([]byte, error)

CalcWitnessSigHash computes the sighash digest for the specified input of the target transaction observing the desired sig hash type.

func DisableLog Uses

func DisableLog()

DisableLog disables all library log output. Logging output is disabled by default until UseLogger is called.

func DisasmString Uses

func DisasmString(buf []byte) (string, error)

DisasmString formats a disassembled script for one line printing. When the script fails to parse, the returned string will contain the disassembled script up to the point the failure occurred along with the string '[error]' appended. In addition, the reason the script failed to parse is returned if the caller wants more information about the failure.

func ExtractWitnessProgramInfo Uses

func ExtractWitnessProgramInfo(script []byte) (int, []byte, error)

ExtractWitnessProgramInfo attempts to extract the witness program version, as well as the witness program itself from the passed script.

func GetPreciseSigOpCount Uses

func GetPreciseSigOpCount(scriptSig, scriptPubKey []byte, bip16 bool) int

GetPreciseSigOpCount returns the number of signature operations in scriptPubKey. If bip16 is true then scriptSig may be searched for the Pay-To-Script-Hash script in order to find the precise number of signature operations in the transaction. If the script fails to parse, then the count up to the point of failure is returned.

func GetSigOpCount Uses

func GetSigOpCount(script []byte) int

GetSigOpCount provides a quick count of the number of signature operations in a script. a CHECKSIG operations counts for 1, and a CHECK_MULTISIG for 20. If the script fails to parse, then the count up to the point of failure is returned.

func GetWitnessSigOpCount Uses

func GetWitnessSigOpCount(sigScript, pkScript []byte, witness wire.TxWitness) int

GetWitnessSigOpCount returns the number of signature operations generated by spending the passed pkScript with the specified witness, or sigScript. Unlike GetPreciseSigOpCount, this function is able to accurately count the number of signature operations generated by spending witness programs, and nested p2sh witness programs. If the script fails to parse, then the count up to the point of failure is returned.

func IsErrorCode Uses

func IsErrorCode(err error, c ErrorCode) bool

IsErrorCode returns whether or not the provided error is a script error with the provided error code.

func IsPayToScriptHash Uses

func IsPayToScriptHash(script []byte) bool

IsPayToScriptHash returns true if the script is in the standard pay-to-script-hash (P2SH) format, false otherwise.

func IsPayToWitnessPubKeyHash Uses

func IsPayToWitnessPubKeyHash(script []byte) bool

IsPayToWitnessPubKeyHash returns true if the is in the standard pay-to-witness-pubkey-hash (P2WKH) format, false otherwise.

func IsPayToWitnessScriptHash Uses

func IsPayToWitnessScriptHash(script []byte) bool

IsPayToWitnessScriptHash returns true if the is in the standard pay-to-witness-script-hash (P2WSH) format, false otherwise.

func IsPushOnlyScript Uses

func IsPushOnlyScript(script []byte) bool

IsPushOnlyScript returns whether or not the passed script only pushes data.

False will be returned when the script does not parse.

func IsUnspendable Uses

func IsUnspendable(pkScript []byte) bool

IsUnspendable returns whether the passed public key script is unspendable, or guaranteed to fail at execution. This allows inputs to be pruned instantly when entering the UTXO set.

func IsWitnessProgram Uses

func IsWitnessProgram(script []byte) bool

IsWitnessProgram returns true if the passed script is a valid witness program which is encoded according to the passed witness program version. A witness program must be a small integer (from 0-16), followed by 2-40 bytes of pushed data.

func MultiSigScript Uses

func MultiSigScript(pubkeys []*btcutil.AddressPubKey, nrequired int) ([]byte, error)

MultiSigScript returns a valid script for a multisignature redemption where nrequired of the keys in pubkeys are required to have signed the transaction for success. An Error with the error code ErrTooManyRequiredSigs will be returned if nrequired is larger than the number of keys provided.

func NullDataScript Uses

func NullDataScript(data []byte) ([]byte, error)

NullDataScript creates a provably-prunable script containing OP_RETURN followed by the passed data. An Error with the error code ErrTooMuchNullData will be returned if the length of the passed data exceeds MaxDataCarrierSize.

func PayToAddrScript Uses

func PayToAddrScript(addr btcutil.Address) ([]byte, error)

PayToAddrScript creates a new script to pay a transaction output to a the specified address.

This example demonstrates creating a script which pays to a bitcoin address. It also prints the created script hex and uses the DisasmString function to display the disassembled script.

Code:

// Parse the address to send the coins to into a btcutil.Address
// which is useful to ensure the accuracy of the address and determine
// the address type.  It is also required for the upcoming call to
// PayToAddrScript.
addressStr := "12gpXQVcCL2qhTNQgyLVdCFG2Qs2px98nV"
address, err := btcutil.DecodeAddress(addressStr, &chaincfg.MainNetParams)
if err != nil {
    fmt.Println(err)
    return
}

// Create a public key script that pays to the address.
script, err := txscript.PayToAddrScript(address)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Printf("Script Hex: %x\n", script)

disasm, err := txscript.DisasmString(script)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println("Script Disassembly:", disasm)

Output:

Script Hex: 76a914128004ff2fcaf13b2b91eb654b1dc2b674f7ec6188ac
Script Disassembly: OP_DUP OP_HASH160 128004ff2fcaf13b2b91eb654b1dc2b674f7ec61 OP_EQUALVERIFY OP_CHECKSIG

func PushedData Uses

func PushedData(script []byte) ([][]byte, error)

PushedData returns an array of byte slices containing any pushed data found in the passed script. This includes OP_0, but not OP_1 - OP_16.

func RawTxInSignature Uses

func RawTxInSignature(tx *wire.MsgTx, idx int, subScript []byte,
    hashType SigHashType, key *btcec.PrivateKey) ([]byte, error)

RawTxInSignature returns the serialized ECDSA signature for the input idx of the given transaction, with hashType appended to it.

func RawTxInWitnessSignature Uses

func RawTxInWitnessSignature(tx *wire.MsgTx, sigHashes *TxSigHashes, idx int,
    amt int64, subScript []byte, hashType SigHashType,
    key *btcec.PrivateKey) ([]byte, error)

RawTxInWitnessSignature returns the serialized ECDA signature for the input idx of the given transaction, with the hashType appended to it. This function is identical to RawTxInSignature, however the signature generated signs a new sighash digest defined in BIP0143.

func SignTxOutput Uses

func SignTxOutput(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
    pkScript []byte, hashType SigHashType, kdb KeyDB, sdb ScriptDB,
    previousScript []byte) ([]byte, error)

SignTxOutput signs output idx of the given tx to resolve the script given in pkScript with a signature type of hashType. Any keys required will be looked up by calling getKey() with the string of the given address. Any pay-to-script-hash signatures will be similarly looked up by calling getScript. If previousScript is provided then the results in previousScript will be merged in a type-dependent manner with the newly generated. signature script.

This example demonstrates manually creating and signing a redeem transaction.

Code:

// Ordinarily the private key would come from whatever storage mechanism
// is being used, but for this example just hard code it.
privKeyBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2" +
    "d4f8720ee63e502ee2869afab7de234b80c")
if err != nil {
    fmt.Println(err)
    return
}
privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), privKeyBytes)
pubKeyHash := btcutil.Hash160(pubKey.SerializeCompressed())
addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash,
    &chaincfg.MainNetParams)
if err != nil {
    fmt.Println(err)
    return
}

// For this example, create a fake transaction that represents what
// would ordinarily be the real transaction that is being spent.  It
// contains a single output that pays to address in the amount of 1 BTC.
originTx := wire.NewMsgTx(wire.TxVersion)
prevOut := wire.NewOutPoint(&chainhash.Hash{}, ^uint32(0))
txIn := wire.NewTxIn(prevOut, []byte{txscript.OP_0, txscript.OP_0}, nil)
originTx.AddTxIn(txIn)
pkScript, err := txscript.PayToAddrScript(addr)
if err != nil {
    fmt.Println(err)
    return
}
txOut := wire.NewTxOut(100000000, pkScript)
originTx.AddTxOut(txOut)
originTxHash := originTx.TxHash()

// Create the transaction to redeem the fake transaction.
redeemTx := wire.NewMsgTx(wire.TxVersion)

// Add the input(s) the redeeming transaction will spend.  There is no
// signature script at this point since it hasn't been created or signed
// yet, hence nil is provided for it.
prevOut = wire.NewOutPoint(&originTxHash, 0)
txIn = wire.NewTxIn(prevOut, nil, nil)
redeemTx.AddTxIn(txIn)

// Ordinarily this would contain that actual destination of the funds,
// but for this example don't bother.
txOut = wire.NewTxOut(0, nil)
redeemTx.AddTxOut(txOut)

// Sign the redeeming transaction.
lookupKey := func(a btcutil.Address) (*btcec.PrivateKey, bool, error) {
    // Ordinarily this function would involve looking up the private
    // key for the provided address, but since the only thing being
    // signed in this example uses the address associated with the
    // private key from above, simply return it with the compressed
    // flag set since the address is using the associated compressed
    // public key.
    //
    // NOTE: If you want to prove the code is actually signing the
    // transaction properly, uncomment the following line which
    // intentionally returns an invalid key to sign with, which in
    // turn will result in a failure during the script execution
    // when verifying the signature.
    //
    // privKey.D.SetInt64(12345)
    //
    return privKey, true, nil
}
// Notice that the script database parameter is nil here since it isn't
// used.  It must be specified when pay-to-script-hash transactions are
// being signed.
sigScript, err := txscript.SignTxOutput(&chaincfg.MainNetParams,
    redeemTx, 0, originTx.TxOut[0].PkScript, txscript.SigHashAll,
    txscript.KeyClosure(lookupKey), nil, nil)
if err != nil {
    fmt.Println(err)
    return
}
redeemTx.TxIn[0].SignatureScript = sigScript

// Prove that the transaction has been validly signed by executing the
// script pair.
flags := txscript.ScriptBip16 | txscript.ScriptVerifyDERSignatures |
    txscript.ScriptStrictMultiSig |
    txscript.ScriptDiscourageUpgradableNops
vm, err := txscript.NewEngine(originTx.TxOut[0].PkScript, redeemTx, 0,
    flags, nil, nil, -1)
if err != nil {
    fmt.Println(err)
    return
}
if err := vm.Execute(); err != nil {
    fmt.Println(err)
    return
}
fmt.Println("Transaction successfully signed")

Output:

Transaction successfully signed

func SignatureScript Uses

func SignatureScript(tx *wire.MsgTx, idx int, subscript []byte, hashType SigHashType, privKey *btcec.PrivateKey, compress bool) ([]byte, error)

SignatureScript creates an input signature script for tx to spend BTC sent from a previous output to the owner of privKey. tx must include all transaction inputs and outputs, however txin scripts are allowed to be filled or empty. The returned script is calculated to be used as the idx'th txin sigscript for tx. subscript is the PkScript of the previous output being used as the idx'th input. privKey is serialized in either a compressed or uncompressed format based on compress. This format must match the same format used to generate the payment address, or the script validation will fail.

func UseLogger Uses

func UseLogger(logger btclog.Logger)

UseLogger uses a specified Logger to output package logging info.

func WitnessSignature Uses

func WitnessSignature(tx *wire.MsgTx, sigHashes *TxSigHashes, idx int, amt int64,
    subscript []byte, hashType SigHashType, privKey *btcec.PrivateKey,
    compress bool) (wire.TxWitness, error)

WitnessSignature creates an input witness stack for tx to spend BTC sent from a previous output to the owner of privKey using the p2wkh script template. The passed transaction must contain all the inputs and outputs as dictated by the passed hashType. The signature generated observes the new transaction digest algorithm defined within BIP0143.

type AtomicSwapDataPushes Uses

type AtomicSwapDataPushes struct {
    RecipientHash160 [20]byte
    RefundHash160    [20]byte
    SecretHash       [32]byte
    SecretSize       int64
    LockTime         int64
}

AtomicSwapDataPushes houses the data pushes found in atomic swap contracts.

func ExtractAtomicSwapDataPushes Uses

func ExtractAtomicSwapDataPushes(version uint16, pkScript []byte) (*AtomicSwapDataPushes, error)

ExtractAtomicSwapDataPushes returns the data pushes from an atomic swap contract. If the script is not an atomic swap contract, ExtractAtomicSwapDataPushes returns (nil, nil). Non-nil errors are returned for unparsable scripts.

NOTE: Atomic swaps are not considered standard script types by the dcrd mempool policy and should be used with P2SH. The atomic swap format is also expected to change to use a more secure hash function in the future.

This function is only defined in the txscript package due to API limitations which prevent callers using txscript to parse nonstandard scripts.

type Engine Uses

type Engine struct {
    // contains filtered or unexported fields
}

Engine is the virtual machine that executes scripts.

func NewEngine Uses

func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags,
    sigCache *SigCache, hashCache *TxSigHashes, inputAmount int64) (*Engine, error)

NewEngine returns a new script engine for the provided public key script, transaction, and input index. The flags modify the behavior of the script engine according to the description provided by each flag.

func (*Engine) CheckErrorCondition Uses

func (vm *Engine) CheckErrorCondition(finalScript bool) error

CheckErrorCondition returns nil if the running script has ended and was successful, leaving a a true boolean on the stack. An error otherwise, including if the script has not finished.

func (*Engine) DisasmPC Uses

func (vm *Engine) DisasmPC() (string, error)

DisasmPC returns the string for the disassembly of the opcode that will be next to execute when Step() is called.

func (*Engine) DisasmScript Uses

func (vm *Engine) DisasmScript(idx int) (string, error)

DisasmScript returns the disassembly string for the script at the requested offset index. Index 0 is the signature script and 1 is the public key script.

func (*Engine) Execute Uses

func (vm *Engine) Execute() (err error)

Execute will execute all scripts in the script engine and return either nil for successful validation or an error if one occurred.

func (*Engine) GetAltStack Uses

func (vm *Engine) GetAltStack() [][]byte

GetAltStack returns the contents of the alternate stack as an array where the last item in the array is the top of the stack.

func (*Engine) GetStack Uses

func (vm *Engine) GetStack() [][]byte

GetStack returns the contents of the primary stack as an array. where the last item in the array is the top of the stack.

func (*Engine) SetAltStack Uses

func (vm *Engine) SetAltStack(data [][]byte)

SetAltStack sets the contents of the alternate stack to the contents of the provided array where the last item in the array will be the top of the stack.

func (*Engine) SetStack Uses

func (vm *Engine) SetStack(data [][]byte)

SetStack sets the contents of the primary stack to the contents of the provided array where the last item in the array will be the top of the stack.

func (*Engine) Step Uses

func (vm *Engine) Step() (done bool, err error)

Step will execute the next instruction and move the program counter to the next opcode in the script, or the next script if the current has ended. Step will return true in the case that the last opcode was successfully executed.

The result of calling Step or any other method is undefined if an error is returned.

type ErrScriptNotCanonical Uses

type ErrScriptNotCanonical string

ErrScriptNotCanonical identifies a non-canonical script. The caller can use a type assertion to detect this error type.

func (ErrScriptNotCanonical) Error Uses

func (e ErrScriptNotCanonical) Error() string

Error implements the error interface.

type Error Uses

type Error struct {
    ErrorCode   ErrorCode
    Description string
}

Error identifies a script-related error. It is used to indicate three classes of errors: 1) Script execution failures due to violating one of the many requirements

imposed by the script engine or evaluating to false

2) Improper API usage by callers 3) Internal consistency check failures

The caller can use type assertions on the returned errors to access the ErrorCode field to ascertain the specific reason for the error. As an additional convenience, the caller may make use of the IsErrorCode function to check for a specific error code.

func (Error) Error Uses

func (e Error) Error() string

Error satisfies the error interface and prints human-readable errors.

type ErrorCode Uses

type ErrorCode int

ErrorCode identifies a kind of script error.

const (
    // ErrInternal is returned if internal consistency checks fail.  In
    // practice this error should never be seen as it would mean there is an
    // error in the engine logic.
    ErrInternal ErrorCode = iota

    // ErrInvalidFlags is returned when the passed flags to NewEngine
    // contain an invalid combination.
    ErrInvalidFlags

    // ErrInvalidIndex is returned when an out-of-bounds index is passed to
    // a function.
    ErrInvalidIndex

    // ErrUnsupportedAddress is returned when a concrete type that
    // implements a btcutil.Address is not a supported type.
    ErrUnsupportedAddress

    // ErrNotMultisigScript is returned from CalcMultiSigStats when the
    // provided script is not a multisig script.
    ErrNotMultisigScript

    // ErrTooManyRequiredSigs is returned from MultiSigScript when the
    // specified number of required signatures is larger than the number of
    // provided public keys.
    ErrTooManyRequiredSigs

    // ErrTooMuchNullData is returned from NullDataScript when the length of
    // the provided data exceeds MaxDataCarrierSize.
    ErrTooMuchNullData

    // ErrEarlyReturn is returned when OP_RETURN is executed in the script.
    ErrEarlyReturn

    // ErrEmptyStack is returned when the script evaluated without error,
    // but terminated with an empty top stack element.
    ErrEmptyStack

    // ErrEvalFalse is returned when the script evaluated without error but
    // terminated with a false top stack element.
    ErrEvalFalse

    // ErrScriptUnfinished is returned when CheckErrorCondition is called on
    // a script that has not finished executing.
    ErrScriptUnfinished

    // ErrScriptDone is returned when an attempt to execute an opcode is
    // made once all of them have already been executed.  This can happen
    // due to things such as a second call to Execute or calling Step after
    // all opcodes have already been executed.
    ErrInvalidProgramCounter

    // ErrScriptTooBig is returned if a script is larger than MaxScriptSize.
    ErrScriptTooBig

    // ErrElementTooBig is returned if the size of an element to be pushed
    // to the stack is over MaxScriptElementSize.
    ErrElementTooBig

    // ErrTooManyOperations is returned if a script has more than
    // MaxOpsPerScript opcodes that do not push data.
    ErrTooManyOperations

    // ErrStackOverflow is returned when stack and altstack combined depth
    // is over the limit.
    ErrStackOverflow

    // ErrInvalidPubKeyCount is returned when the number of public keys
    // specified for a multsig is either negative or greater than
    // MaxPubKeysPerMultiSig.
    ErrInvalidPubKeyCount

    // ErrInvalidSignatureCount is returned when the number of signatures
    // specified for a multisig is either negative or greater than the
    // number of public keys.
    ErrInvalidSignatureCount

    // ErrNumberTooBig is returned when the argument for an opcode that
    // expects numeric input is larger than the expected maximum number of
    // bytes.  For the most part, opcodes that deal with stack manipulation
    // via offsets, arithmetic, numeric comparison, and boolean logic are
    // those that this applies to.  However, any opcode that expects numeric
    // input may fail with this code.
    ErrNumberTooBig

    // ErrVerify is returned when OP_VERIFY is encountered in a script and
    // the top item on the data stack does not evaluate to true.
    ErrVerify

    // ErrEqualVerify is returned when OP_EQUALVERIFY is encountered in a
    // script and the top item on the data stack does not evaluate to true.
    ErrEqualVerify

    // ErrNumEqualVerify is returned when OP_NUMEQUALVERIFY is encountered
    // in a script and the top item on the data stack does not evaluate to
    // true.
    ErrNumEqualVerify

    // ErrCheckSigVerify is returned when OP_CHECKSIGVERIFY is encountered
    // in a script and the top item on the data stack does not evaluate to
    // true.
    ErrCheckSigVerify

    // ErrCheckSigVerify is returned when OP_CHECKMULTISIGVERIFY is
    // encountered in a script and the top item on the data stack does not
    // evaluate to true.
    ErrCheckMultiSigVerify

    // ErrDisabledOpcode is returned when a disabled opcode is encountered
    // in a script.
    ErrDisabledOpcode

    // ErrReservedOpcode is returned when an opcode marked as reserved
    // is encountered in a script.
    ErrReservedOpcode

    // ErrMalformedPush is returned when a data push opcode tries to push
    // more bytes than are left in the script.
    ErrMalformedPush

    // ErrInvalidStackOperation is returned when a stack operation is
    // attempted with a number that is invalid for the current stack size.
    ErrInvalidStackOperation

    // ErrUnbalancedConditional is returned when an OP_ELSE or OP_ENDIF is
    // encountered in a script without first having an OP_IF or OP_NOTIF or
    // the end of script is reached without encountering an OP_ENDIF when
    // an OP_IF or OP_NOTIF was previously encountered.
    ErrUnbalancedConditional

    // ErrMinimalData is returned when the ScriptVerifyMinimalData flag
    // is set and the script contains push operations that do not use
    // the minimal opcode required.
    ErrMinimalData

    // ErrInvalidSigHashType is returned when a signature hash type is not
    // one of the supported types.
    ErrInvalidSigHashType

    // ErrSigTooShort is returned when a signature that should be a
    // canonically-encoded DER signature is too short.
    ErrSigTooShort

    // ErrSigTooLong is returned when a signature that should be a
    // canonically-encoded DER signature is too long.
    ErrSigTooLong

    // ErrSigInvalidSeqID is returned when a signature that should be a
    // canonically-encoded DER signature does not have the expected ASN.1
    // sequence ID.
    ErrSigInvalidSeqID

    // ErrSigInvalidDataLen is returned a signature that should be a
    // canonically-encoded DER signature does not specify the correct number
    // of remaining bytes for the R and S portions.
    ErrSigInvalidDataLen

    // ErrSigMissingSTypeID is returned a signature that should be a
    // canonically-encoded DER signature does not provide the ASN.1 type ID
    // for S.
    ErrSigMissingSTypeID

    // ErrSigMissingSLen is returned when a signature that should be a
    // canonically-encoded DER signature does not provide the length of S.
    ErrSigMissingSLen

    // ErrSigInvalidSLen is returned a signature that should be a
    // canonically-encoded DER signature does not specify the correct number
    // of bytes for the S portion.
    ErrSigInvalidSLen

    // ErrSigInvalidRIntID is returned when a signature that should be a
    // canonically-encoded DER signature does not have the expected ASN.1
    // integer ID for R.
    ErrSigInvalidRIntID

    // ErrSigZeroRLen is returned when a signature that should be a
    // canonically-encoded DER signature has an R length of zero.
    ErrSigZeroRLen

    // ErrSigNegativeR is returned when a signature that should be a
    // canonically-encoded DER signature has a negative value for R.
    ErrSigNegativeR

    // ErrSigTooMuchRPadding is returned when a signature that should be a
    // canonically-encoded DER signature has too much padding for R.
    ErrSigTooMuchRPadding

    // ErrSigInvalidSIntID is returned when a signature that should be a
    // canonically-encoded DER signature does not have the expected ASN.1
    // integer ID for S.
    ErrSigInvalidSIntID

    // ErrSigZeroSLen is returned when a signature that should be a
    // canonically-encoded DER signature has an S length of zero.
    ErrSigZeroSLen

    // ErrSigNegativeS is returned when a signature that should be a
    // canonically-encoded DER signature has a negative value for S.
    ErrSigNegativeS

    // ErrSigTooMuchSPadding is returned when a signature that should be a
    // canonically-encoded DER signature has too much padding for S.
    ErrSigTooMuchSPadding

    // ErrSigHighS is returned when the ScriptVerifyLowS flag is set and the
    // script contains any signatures whose S values are higher than the
    // half order.
    ErrSigHighS

    // ErrNotPushOnly is returned when a script that is required to only
    // push data to the stack performs other operations.  A couple of cases
    // where this applies is for a pay-to-script-hash signature script when
    // bip16 is active and when the ScriptVerifySigPushOnly flag is set.
    ErrNotPushOnly

    // ErrSigNullDummy is returned when the ScriptStrictMultiSig flag is set
    // and a multisig script has anything other than 0 for the extra dummy
    // argument.
    ErrSigNullDummy

    // ErrPubKeyType is returned when the ScriptVerifyStrictEncoding
    // flag is set and the script contains invalid public keys.
    ErrPubKeyType

    // ErrCleanStack is returned when the ScriptVerifyCleanStack flag
    // is set, and after evalution, the stack does not contain only a
    // single element.
    ErrCleanStack

    // ErrNullFail is returned when the ScriptVerifyNullFail flag is
    // set and signatures are not empty on failed checksig or checkmultisig
    // operations.
    ErrNullFail

    // ErrWitnessMalleated is returned if ScriptVerifyWitness is set and a
    // native p2wsh program is encountered which has a non-empty sigScript.
    ErrWitnessMalleated

    // ErrWitnessMalleatedP2SH is returned if ScriptVerifyWitness if set
    // and the validation logic for nested p2sh encounters a sigScript
    // which isn't *exactyl* a datapush of the witness program.
    ErrWitnessMalleatedP2SH

    // ErrDiscourageUpgradableNOPs is returned when the
    // ScriptDiscourageUpgradableNops flag is set and a NOP opcode is
    // encountered in a script.
    ErrDiscourageUpgradableNOPs

    // ErrNegativeLockTime is returned when a script contains an opcode that
    // interprets a negative lock time.
    ErrNegativeLockTime

    // ErrUnsatisfiedLockTime is returned when a script contains an opcode
    // that involves a lock time and the required lock time has not been
    // reached.
    ErrUnsatisfiedLockTime

    // ErrMinimalIf is returned if ScriptVerifyWitness is set and the
    // operand of an OP_IF/OP_NOF_IF are not either an empty vector or
    // [0x01].
    ErrMinimalIf

    // ErrDiscourageUpgradableWitnessProgram is returned if
    // ScriptVerifyWitness is set and the versino of an executing witness
    // program is outside the set of currently defined witness program
    // vesions.
    ErrDiscourageUpgradableWitnessProgram

    // ErrWitnessProgramEmpty is returned if ScriptVerifyWitness is set and
    // the witness stack itself is empty.
    ErrWitnessProgramEmpty

    // ErrWitnessProgramMismatch is returned if ScriptVerifyWitness is set
    // and the witness itself for a p2wkh witness program isn't *exactly* 2
    // items or if the witness for a p2wsh isn't the sha255 of the witness
    // script.
    ErrWitnessProgramMismatch

    // ErrWitnessProgramWrongLength is returned if ScriptVerifyWitness is
    // set and the length of the witness program violates the length as
    // dictated by the current witness version.
    ErrWitnessProgramWrongLength

    // ErrWitnessUnexpected is returned if ScriptVerifyWitness is set and a
    // transaction includes witness data but doesn't spend an which is a
    // witness program (nested or native).
    ErrWitnessUnexpected

    // ErrWitnessPubKeyType is returned if ScriptVerifyWitness is set and
    // the public key used in either a check-sig or check-multi-sig isn't
    // serialized in a compressed format.
    ErrWitnessPubKeyType
)

These constants are used to identify a specific Error.

func (ErrorCode) String Uses

func (e ErrorCode) String() string

String returns the ErrorCode as a human-readable name.

type HashCache Uses

type HashCache struct {
    sync.RWMutex
    // contains filtered or unexported fields
}

HashCache houses a set of partial sighashes keyed by txid. The set of partial sighashes are those introduced within BIP0143 by the new more efficient sighash digest calculation algorithm. Using this threadsafe shared cache, multiple goroutines can safely re-use the pre-computed partial sighashes speeding up validation time amongst all inputs found within a block.

func NewHashCache Uses

func NewHashCache(maxSize uint) *HashCache

NewHashCache returns a new instance of the HashCache given a maximum number of entries which may exist within it at anytime.

func (*HashCache) AddSigHashes Uses

func (h *HashCache) AddSigHashes(tx *wire.MsgTx)

AddSigHashes computes, then adds the partial sighashes for the passed transaction.

func (*HashCache) ContainsHashes Uses

func (h *HashCache) ContainsHashes(txid *chainhash.Hash) bool

ContainsHashes returns true if the partial sighashes for the passed transaction currently exist within the HashCache, and false otherwise.

func (*HashCache) GetSigHashes Uses

func (h *HashCache) GetSigHashes(txid *chainhash.Hash) (*TxSigHashes, bool)

GetSigHashes possibly returns the previously cached partial sighashes for the passed transaction. This function also returns an additional boolean value indicating if the sighashes for the passed transaction were found to be present within the HashCache.

func (*HashCache) PurgeSigHashes Uses

func (h *HashCache) PurgeSigHashes(txid *chainhash.Hash)

PurgeSigHashes removes all partial sighashes from the HashCache belonging to the passed transaction.

type KeyClosure Uses

type KeyClosure func(btcutil.Address) (*btcec.PrivateKey, bool, error)

KeyClosure implements KeyDB with a closure.

func (KeyClosure) GetKey Uses

func (kc KeyClosure) GetKey(address btcutil.Address) (*btcec.PrivateKey,
    bool, error)

GetKey implements KeyDB by returning the result of calling the closure.

type KeyDB Uses

type KeyDB interface {
    GetKey(btcutil.Address) (*btcec.PrivateKey, bool, error)
}

KeyDB is an interface type provided to SignTxOutput, it encapsulates any user state required to get the private keys for an address.

type PkScript Uses

type PkScript struct {
    // contains filtered or unexported fields
}

PkScript is a wrapper struct around a byte array, allowing it to be used as a map index.

func ComputePkScript Uses

func ComputePkScript(sigScript []byte, witness wire.TxWitness) (PkScript, error)

ComputePkScript computes the script of an output by looking at the spending input's signature script or witness.

NOTE: Only P2PKH, P2SH, P2WSH, and P2WPKH redeem scripts are supported.

func ParsePkScript Uses

func ParsePkScript(pkScript []byte) (PkScript, error)

ParsePkScript parses an output script into the PkScript struct. ErrUnsupportedScriptType is returned when attempting to parse an unsupported script type.

func (PkScript) Address Uses

func (s PkScript) Address(chainParams *chaincfg.Params) (btcutil.Address, error)

Address encodes the script into an address for the given chain.

func (PkScript) Class Uses

func (s PkScript) Class() ScriptClass

Class returns the script type.

func (PkScript) Script Uses

func (s PkScript) Script() []byte

Script returns the script as a byte slice without any padding.

func (PkScript) String Uses

func (s PkScript) String() string

String returns a hex-encoded string representation of the script.

type ScriptBuilder Uses

type ScriptBuilder struct {
    // contains filtered or unexported fields
}

ScriptBuilder provides a facility for building custom scripts. It allows you to push opcodes, ints, and data while respecting canonical encoding. In general it does not ensure the script will execute correctly, however any data pushes which would exceed the maximum allowed script engine limits and are therefore guaranteed not to execute will not be pushed and will result in the Script function returning an error.

For example, the following would build a 2-of-3 multisig script for usage in a pay-to-script-hash (although in this situation MultiSigScript() would be a better choice to generate the script):

builder := txscript.NewScriptBuilder()
builder.AddOp(txscript.OP_2).AddData(pubKey1).AddData(pubKey2)
builder.AddData(pubKey3).AddOp(txscript.OP_3)
builder.AddOp(txscript.OP_CHECKMULTISIG)
script, err := builder.Script()
if err != nil {
	// Handle the error.
	return
}
fmt.Printf("Final multi-sig script: %x\n", script)

func NewScriptBuilder Uses

func NewScriptBuilder() *ScriptBuilder

NewScriptBuilder returns a new instance of a script builder. See ScriptBuilder for details.

func (*ScriptBuilder) AddData Uses

func (b *ScriptBuilder) AddData(data []byte) *ScriptBuilder

AddData pushes the passed data to the end of the script. It automatically chooses canonical opcodes depending on the length of the data. A zero length buffer will lead to a push of empty data onto the stack (OP_0) and any push of data greater than MaxScriptElementSize will not modify the script since that is not allowed by the script engine. Also, the script will not be modified if pushing the data would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddFullData Uses

func (b *ScriptBuilder) AddFullData(data []byte) *ScriptBuilder

AddFullData should not typically be used by ordinary users as it does not include the checks which prevent data pushes larger than the maximum allowed sizes which leads to scripts that can't be executed. This is provided for testing purposes such as regression tests where sizes are intentionally made larger than allowed.

Use AddData instead.

func (*ScriptBuilder) AddInt64 Uses

func (b *ScriptBuilder) AddInt64(val int64) *ScriptBuilder

AddInt64 pushes the passed integer to the end of the script. The script will not be modified if pushing the data would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddOp Uses

func (b *ScriptBuilder) AddOp(opcode byte) *ScriptBuilder

AddOp pushes the passed opcode to the end of the script. The script will not be modified if pushing the opcode would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddOps Uses

func (b *ScriptBuilder) AddOps(opcodes []byte) *ScriptBuilder

AddOps pushes the passed opcodes to the end of the script. The script will not be modified if pushing the opcodes would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) Reset Uses

func (b *ScriptBuilder) Reset() *ScriptBuilder

Reset resets the script so it has no content.

func (*ScriptBuilder) Script Uses

func (b *ScriptBuilder) Script() ([]byte, error)

Script returns the currently built script. When any errors occurred while building the script, the script will be returned up the point of the first error along with the error.

type ScriptClass Uses

type ScriptClass byte

ScriptClass is an enumeration for the list of standard types of script.

const (
    NonStandardTy         ScriptClass = iota // None of the recognized forms.
    PubKeyTy                                 // Pay pubkey.
    PubKeyHashTy                             // Pay pubkey hash.
    WitnessV0PubKeyHashTy                    // Pay witness pubkey hash.
    ScriptHashTy                             // Pay to script hash.
    WitnessV0ScriptHashTy                    // Pay to witness script hash.
    MultiSigTy                               // Multi signature.
    NullDataTy                               // Empty data-only (provably prunable).
)

Classes of script payment known about in the blockchain.

func ExtractPkScriptAddrs Uses

func ExtractPkScriptAddrs(pkScript []byte, chainParams *chaincfg.Params) (ScriptClass, []btcutil.Address, int, error)

ExtractPkScriptAddrs returns the type of script, addresses and required signatures associated with the passed PkScript. Note that it only works for 'standard' transaction script types. Any data such as public keys which are invalid are omitted from the results.

This example demonstrates extracting information from a standard public key script.

Code:

// Start with a standard pay-to-pubkey-hash script.
scriptHex := "76a914128004ff2fcaf13b2b91eb654b1dc2b674f7ec6188ac"
script, err := hex.DecodeString(scriptHex)
if err != nil {
    fmt.Println(err)
    return
}

// Extract and print details from the script.
scriptClass, addresses, reqSigs, err := txscript.ExtractPkScriptAddrs(
    script, &chaincfg.MainNetParams)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println("Script Class:", scriptClass)
fmt.Println("Addresses:", addresses)
fmt.Println("Required Signatures:", reqSigs)

Output:

Script Class: pubkeyhash
Addresses: [12gpXQVcCL2qhTNQgyLVdCFG2Qs2px98nV]
Required Signatures: 1

func GetScriptClass Uses

func GetScriptClass(script []byte) ScriptClass

GetScriptClass returns the class of the script passed.

NonStandardTy will be returned when the script does not parse.

func (ScriptClass) String Uses

func (t ScriptClass) String() string

String implements the Stringer interface by returning the name of the enum script class. If the enum is invalid then "Invalid" will be returned.

type ScriptClosure Uses

type ScriptClosure func(btcutil.Address) ([]byte, error)

ScriptClosure implements ScriptDB with a closure.

func (ScriptClosure) GetScript Uses

func (sc ScriptClosure) GetScript(address btcutil.Address) ([]byte, error)

GetScript implements ScriptDB by returning the result of calling the closure.

type ScriptDB Uses

type ScriptDB interface {
    GetScript(btcutil.Address) ([]byte, error)
}

ScriptDB is an interface type provided to SignTxOutput, it encapsulates any user state required to get the scripts for an pay-to-script-hash address.

type ScriptFlags Uses

type ScriptFlags uint32

ScriptFlags is a bitmask defining additional operations or tests that will be done when executing a script pair.

const (
    // ScriptBip16 defines whether the bip16 threshold has passed and thus
    // pay-to-script hash transactions will be fully validated.
    ScriptBip16 ScriptFlags = 1 << iota

    // ScriptStrictMultiSig defines whether to verify the stack item
    // used by CHECKMULTISIG is zero length.
    ScriptStrictMultiSig

    // ScriptDiscourageUpgradableNops defines whether to verify that
    // NOP1 through NOP10 are reserved for future soft-fork upgrades.  This
    // flag must not be used for consensus critical code nor applied to
    // blocks as this flag is only for stricter standard transaction
    // checks.  This flag is only applied when the above opcodes are
    // executed.
    ScriptDiscourageUpgradableNops

    // ScriptVerifyCheckLockTimeVerify defines whether to verify that
    // a transaction output is spendable based on the locktime.
    // This is BIP0065.
    ScriptVerifyCheckLockTimeVerify

    // ScriptVerifyCheckSequenceVerify defines whether to allow execution
    // pathways of a script to be restricted based on the age of the output
    // being spent.  This is BIP0112.
    ScriptVerifyCheckSequenceVerify

    // ScriptVerifyCleanStack defines that the stack must contain only
    // one stack element after evaluation and that the element must be
    // true if interpreted as a boolean.  This is rule 6 of BIP0062.
    // This flag should never be used without the ScriptBip16 flag nor the
    // ScriptVerifyWitness flag.
    ScriptVerifyCleanStack

    // ScriptVerifyDERSignatures defines that signatures are required
    // to compily with the DER format.
    ScriptVerifyDERSignatures

    // ScriptVerifyLowS defines that signtures are required to comply with
    // the DER format and whose S value is <= order / 2.  This is rule 5
    // of BIP0062.
    ScriptVerifyLowS

    // ScriptVerifyMinimalData defines that signatures must use the smallest
    // push operator. This is both rules 3 and 4 of BIP0062.
    ScriptVerifyMinimalData

    // ScriptVerifyNullFail defines that signatures must be empty if
    // a CHECKSIG or CHECKMULTISIG operation fails.
    ScriptVerifyNullFail

    // ScriptVerifySigPushOnly defines that signature scripts must contain
    // only pushed data.  This is rule 2 of BIP0062.
    ScriptVerifySigPushOnly

    // ScriptVerifyStrictEncoding defines that signature scripts and
    // public keys must follow the strict encoding requirements.
    ScriptVerifyStrictEncoding

    // ScriptVerifyWitness defines whether or not to verify a transaction
    // output using a witness program template.
    ScriptVerifyWitness

    // ScriptVerifyDiscourageUpgradeableWitnessProgram makes witness
    // program with versions 2-16 non-standard.
    ScriptVerifyDiscourageUpgradeableWitnessProgram

    // ScriptVerifyMinimalIf makes a script with an OP_IF/OP_NOTIF whose
    // operand is anything other than empty vector or [0x01] non-standard.
    ScriptVerifyMinimalIf

    // ScriptVerifyWitnessPubKeyType makes a script within a check-sig
    // operation whose public key isn't serialized in a compressed format
    // non-standard.
    ScriptVerifyWitnessPubKeyType
)

type ScriptInfo Uses

type ScriptInfo struct {
    // PkScriptClass is the class of the public key script and is equivalent
    // to calling GetScriptClass on it.
    PkScriptClass ScriptClass

    // NumInputs is the number of inputs provided by the public key script.
    NumInputs int

    // ExpectedInputs is the number of outputs required by the signature
    // script and any pay-to-script-hash scripts. The number will be -1 if
    // unknown.
    ExpectedInputs int

    // SigOps is the number of signature operations in the script pair.
    SigOps int
}

ScriptInfo houses information about a script pair that is determined by CalcScriptInfo.

func CalcScriptInfo Uses

func CalcScriptInfo(sigScript, pkScript []byte, witness wire.TxWitness,
    bip16, segwit bool) (*ScriptInfo, error)

CalcScriptInfo returns a structure providing data about the provided script pair. It will error if the pair is in someway invalid such that they can not be analysed, i.e. if they do not parse or the pkScript is not a push-only script

type SigCache Uses

type SigCache struct {
    sync.RWMutex
    // contains filtered or unexported fields
}

SigCache implements an ECDSA signature verification cache with a randomized entry eviction policy. Only valid signatures will be added to the cache. The benefits of SigCache are two fold. Firstly, usage of SigCache mitigates a DoS attack wherein an attack causes a victim's client to hang due to worst-case behavior triggered while processing attacker crafted invalid transactions. A detailed description of the mitigated DoS attack can be found here: https://bitslog.wordpress.com/2013/01/23/fixed-bitcoin-vulnerability-explanation-why-the-signature-cache-is-a-dos-protection/. Secondly, usage of the SigCache introduces a signature verification optimization which speeds up the validation of transactions within a block, if they've already been seen and verified within the mempool.

func NewSigCache Uses

func NewSigCache(maxEntries uint) *SigCache

NewSigCache creates and initializes a new instance of SigCache. Its sole parameter 'maxEntries' represents the maximum number of entries allowed to exist in the SigCache at any particular moment. Random entries are evicted to make room for new entries that would cause the number of entries in the cache to exceed the max.

func (*SigCache) Add Uses

func (s *SigCache) Add(sigHash chainhash.Hash, sig *btcec.Signature, pubKey *btcec.PublicKey)

Add adds an entry for a signature over 'sigHash' under public key 'pubKey' to the signature cache. In the event that the SigCache is 'full', an existing entry is randomly chosen to be evicted in order to make space for the new entry.

NOTE: This function is safe for concurrent access. Writers will block simultaneous readers until function execution has concluded.

func (*SigCache) Exists Uses

func (s *SigCache) Exists(sigHash chainhash.Hash, sig *btcec.Signature, pubKey *btcec.PublicKey) bool

Exists returns true if an existing entry of 'sig' over 'sigHash' for public key 'pubKey' is found within the SigCache. Otherwise, false is returned.

NOTE: This function is safe for concurrent access. Readers won't be blocked unless there exists a writer, adding an entry to the SigCache.

type SigHashType Uses

type SigHashType uint32

SigHashType represents hash type bits at the end of a signature.

const (
    SigHashOld          SigHashType = 0x0
    SigHashAll          SigHashType = 0x1
    SigHashNone         SigHashType = 0x2
    SigHashSingle       SigHashType = 0x3
    SigHashAnyOneCanPay SigHashType = 0x80
)

Hash type bits from the end of a signature.

type TxSigHashes Uses

type TxSigHashes struct {
    HashPrevOuts chainhash.Hash
    HashSequence chainhash.Hash
    HashOutputs  chainhash.Hash
}

TxSigHashes houses the partial set of sighashes introduced within BIP0143. This partial set of sighashes may be re-used within each input across a transaction when validating all inputs. As a result, validation complexity for SigHashAll can be reduced by a polynomial factor.

func NewTxSigHashes Uses

func NewTxSigHashes(tx *wire.MsgTx) *TxSigHashes

NewTxSigHashes computes, and returns the cached sighashes of the given transaction.

Package txscript imports 18 packages (graph) and is imported by 795 packages. Updated 2019-06-06. Refresh now. Tools for package owners.