Documentation
¶
Overview ¶
A library for working with the elliptic curves needed for bitcoin
Copyright 2010 The Go Authors. All rights reserved. Copyright 2011 ThePiachu. All rights reserved. Copyright 2013-2014 The btcsuite developers license that can be found in the LICENSE file.
+build gensecp256k1
Copyright 2015 The btcsuite developers license that can be found in the LICENSE file.
Copyright (c) 2015 The btcsuite developers license that can be found in the LICENSE file.
Example (DecryptMessage) ¶
This example demonstrates decrypting a message using a private key that is first parsed from raw bytes.
// Decode the hex-encoded private key.
pkBytes, err := hex.DecodeString("a11b0a4e1a132305652ee7a8eb7848f6ad" +
"5ea381e3ce20a2c086a2e388230811")
if err != nil {
fmt.Println(err)
return
}
privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)
ciphertext, err := hex.DecodeString("35f644fbfb208bc71e57684c3c8b437402ca" +
"002047a2f1b38aa1a8f1d5121778378414f708fe13ebf7b4a7bb74407288c1958969" +
"00207cf4ac6057406e40f79961c973309a892732ae7a74ee96cd89823913b8b8d650" +
"a44166dc61ea1c419d47077b748a9c06b8d57af72deb2819d98a9d503efc59fc8307" +
"d14174f8b83354fac3ff56075162")
// Try decrypting the message.
plaintext, err := btcec.Decrypt(privKey, ciphertext)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(string(plaintext))
Output: test message
Example (EncryptMessage) ¶
parsed from raw bytes, then decrypting it using the corresponding private key.
// Decode the hex-encoded pubkey of the recipient.
pubKeyBytes, err := hex.DecodeString("04115c42e757b2efb7671c578530ec191a1" +
"359381e6a71127a9d37c486fd30dae57e76dc58f693bd7e7010358ce6b165e483a29" +
"21010db67ac11b1b51b651953d2") // uncompressed pubkey
if err != nil {
fmt.Println(err)
return
}
pubKey, err := btcec.ParsePubKey(pubKeyBytes, btcec.S256())
if err != nil {
fmt.Println(err)
return
}
// Encrypt a message decryptable by the private key corresponding to pubKey
message := "test message"
ciphertext, err := btcec.Encrypt(pubKey, []byte(message))
if err != nil {
fmt.Println(err)
return
}
// Decode the hex-encoded private key.
pkBytes, err := hex.DecodeString("a11b0a4e1a132305652ee7a8eb7848f6ad" +
"5ea381e3ce20a2c086a2e388230811")
if err != nil {
fmt.Println(err)
return
}
// note that we already have corresponding pubKey
privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)
// Try decrypting and verify if it's the same message.
plaintext, err := btcec.Decrypt(privKey, ciphertext)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(string(plaintext))
Output: test message
Example (SignMessage) ¶
This example demonstrates signing a message with a secp256k1 private key that
// Decode a hex-encoded private key.
pkBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2d4f87" +
"20ee63e502ee2869afab7de234b80c")
if err != nil {
fmt.Println(err)
return
}
privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)
// Sign a message using the private key.
message := "test message"
messageHash := chainhash.DoubleHashB([]byte(message))
signature, err := privKey.Sign(messageHash)
if err != nil {
fmt.Println(err)
return
}
// Serialize and display the signature.
fmt.Printf("Serialized Signature: %x\n", signature.Serialize())
// Verify the signature for the message using the public key.
verified := signature.Verify(messageHash, pubKey)
fmt.Printf("Signature Verified? %v\n", verified)
Output: Serialized Signature: 304402201008e236fa8cd0f25df4482dddbb622e8a8b26ef0ba731719458de3ccd93805b022032f8ebe514ba5f672466eba334639282616bb3c2f0ab09998037513d1f9e3d6d Signature Verified? true
Example (VerifySignature) ¶
This example demonstrates verifying a secp256k1 signature against a public raw bytes.
// Decode hex-encoded serialized public key.
pubKeyBytes, err := hex.DecodeString("02a673638cb9587cb68ea08dbef685c" +
"6f2d2a751a8b3c6f2a7e9a4999e6e4bfaf5")
if err != nil {
fmt.Println(err)
return
}
pubKey, err := btcec.ParsePubKey(pubKeyBytes, btcec.S256())
if err != nil {
fmt.Println(err)
return
}
// Decode hex-encoded serialized signature.
sigBytes, err := hex.DecodeString("30450220090ebfb3690a0ff115bb1b38b" +
"8b323a667b7653454f1bccb06d4bbdca42c2079022100ec95778b51e707" +
"1cb1205f8bde9af6592fc978b0452dafe599481c46d6b2e479")
if err != nil {
fmt.Println(err)
return
}
signature, err := btcec.ParseSignature(sigBytes, btcec.S256())
if err != nil {
fmt.Println(err)
return
}
// Verify the signature for the message using the public key.
message := "test message"
messageHash := chainhash.DoubleHashB([]byte(message))
verified := signature.Verify(messageHash, pubKey)
fmt.Println("Signature Verified?", verified)
Output: Signature Verified? true
Index ¶
- Constants
- Variables
- func Decrypt(priv *PrivateKey, in []byte) ([]byte, error)
- func Encrypt(pubkey *PublicKey, in []byte) ([]byte, error)
- func GenerateSharedSecret(privkey *PrivateKey, pubkey *PublicKey) []byte
- func IsCompressedPubKey(pubKey []byte) bool
- func NAF(k []byte) ([]byte, []byte)
- func PrivKeyFromBytes(curve elliptic.Curve, pk []byte) (*PrivateKey, *PublicKey)
- func SignCompact(curve *KoblitzCurve, key *PrivateKey, hash []byte, isCompressedKey bool) ([]byte, error)
- type KoblitzCurve
- func (curve *KoblitzCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
- func (curve *KoblitzCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)
- func (curve *KoblitzCurve) EndomorphismVectors() (a1, b1, a2, b2 *big.Int)
- func (curve *KoblitzCurve) IsOnCurve(x, y *big.Int) bool
- func (curve *KoblitzCurve) Params() *elliptic.CurveParams
- func (curve *KoblitzCurve) QPlus1Div4() *big.Int
- func (curve *KoblitzCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)
- func (curve *KoblitzCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)
- func (curve *KoblitzCurve) SerializedBytePoints() []byte
- type PrivateKey
- type PublicKey
- type Signature
Examples ¶
Constants ¶
const ( PubKeyBytesLenCompressed = 33 PubKeyBytesLenUncompressed = 65 PubKeyBytesLenHybrid = 65 )
These constants define the lengths of serialized public keys.
const PrivKeyBytesLen = 32
PrivKeyBytesLen defines the length in bytes of a serialized private key.
Variables ¶
var ( // ErrInvalidMAC occurs when Message Authentication Check (MAC) fails // during decryption. This happens because of either invalid private key or // corrupt ciphertext. ErrInvalidMAC = errors.New("invalid mac hash") )
Functions ¶
func Decrypt ¶
func Decrypt(priv *PrivateKey, in []byte) ([]byte, error)
Decrypt decrypts data that was encrypted using the Encrypt function.
func Encrypt ¶
Encrypt encrypts data for the target public key using AES-256-CBC. It also is:
struct {
// Initialization Vector used for AES-256-CBC
IV [16]byte
// Public Key: curve(2) + len_of_pubkeyX(2) + pubkeyX +
// len_of_pubkeyY(2) + pubkeyY (curve = 714)
PublicKey [70]byte
// Cipher text
Data []byte
// HMAC-SHA-256 Message Authentication Code
HMAC [32]byte
}
to section 5.8.1 of ANSI X9.63 for rationale on this format.
func GenerateSharedSecret ¶
func GenerateSharedSecret(privkey *PrivateKey, pubkey *PublicKey) []byte
GenerateSharedSecret generates a shared secret based on a private key and a public key using Diffie-Hellman key exchange (ECDH) (RFC 4753). RFC5903 Section 9 states we should only return x.
func IsCompressedPubKey ¶
IsCompressedPubKey returns true the the passed serialized public key has been encoded in compressed format, and false otherwise.
func NAF ¶
NAF takes a positive integer k and returns the Non-Adjacent Form (NAF) as two
Essentially, this makes it possible to minimize the number of operations since the resulting ints returned will be at least 50% 0s.
func PrivKeyFromBytes ¶
func PrivKeyFromBytes(curve elliptic.Curve, pk []byte) (*PrivateKey, *PublicKey)
PrivKeyFromBytes returns a private and public key for `curve' based on the private key passed as an argument as a byte slice.
func SignCompact ¶
func SignCompact(curve *KoblitzCurve, key *PrivateKey, hash []byte, isCompressedKey bool) ([]byte, error)
SignCompact produces a compact signature of the data in hash with the given private key on the given koblitz curve. The isCompressed parameter should be used to detail if the given signature should reference a compressed public key or not. If successful the bytes of the compact signature will be returned in the format: <(byte of 27+public key solution)+4 if compressed >< padded bytes for signature R><padded bytes for signature S> where the R and S parameters are padde up to the bitlengh of the curve.
Types ¶
type KoblitzCurve ¶
type KoblitzCurve struct {
*elliptic.CurveParams
H int // cofactor of the curve.
// contains filtered or unexported fields
}
KoblitzCurve supports a koblitz curve implementation that fits the ECC Curve interface from crypto/elliptic.
func (*KoblitzCurve) Add ¶
Add returns the sum of (x1,y1) and (x2,y2). Part of the elliptic.Curve interface.
func (*KoblitzCurve) EndomorphismVectors ¶
func (curve *KoblitzCurve) EndomorphismVectors() (a1, b1, a2, b2 *big.Int)
EndomorphismVectors runs the first 3 steps of algorithm 3.74 from [GECC] to generate the linearly independent vectors needed to generate a balanced length-two representation of a multiplier such that k = k1 + k2λ (mod N) and returns them. Since the values will always be the same given the fact that N and λ are fixed, the final results can be accelerated by storing the precomputed values with the curve.
func (*KoblitzCurve) IsOnCurve ¶
func (curve *KoblitzCurve) IsOnCurve(x, y *big.Int) bool
Part of the elliptic.Curve interface. This function differs from the crypto/elliptic algorithm since a = 0 not -3.
func (*KoblitzCurve) Params ¶
func (curve *KoblitzCurve) Params() *elliptic.CurveParams
Params returns the parameters for the curve.
func (*KoblitzCurve) QPlus1Div4 ¶
func (curve *KoblitzCurve) QPlus1Div4() *big.Int
QPlus1Div4 returns the Q+1/4 constant for the curve for use in calculating square roots via exponention.
func (*KoblitzCurve) ScalarBaseMult ¶
big endian integer. Part of the elliptic.Curve interface.
func (*KoblitzCurve) ScalarMult ¶
Part of the elliptic.Curve interface.
func (*KoblitzCurve) SerializedBytePoints ¶
func (curve *KoblitzCurve) SerializedBytePoints() []byte
SerializedBytePoints returns a serialized byte slice which contains all of secp256k1.go.
type PrivateKey ¶
type PrivateKey ecdsa.PrivateKey
PrivateKey wraps an ecdsa.PrivateKey as a convenience mainly for signing things with the the private key without having to directly import the ecdsa package.
func NewPrivateKey ¶
func NewPrivateKey(curve elliptic.Curve) (*PrivateKey, error)
instead of the normal ecdsa.PrivateKey.
func (*PrivateKey) PubKey ¶
func (p *PrivateKey) PubKey() *PublicKey
PubKey returns the PublicKey corresponding to this private key.
func (*PrivateKey) Serialize ¶
func (p *PrivateKey) Serialize() []byte
Serialize returns the private key number d as a big-endian binary-encoded number, padded to a length of 32 bytes.
func (*PrivateKey) Sign ¶
func (p *PrivateKey) Sign(hash []byte) (*Signature, error)
Sign generates an ECDSA signature for the provided hash (which should be the result of hashing a larger message) using the private key. Produced signature in accordance with RFC6979 and BIP0062.
func (*PrivateKey) ToECDSA ¶
func (p *PrivateKey) ToECDSA() *ecdsa.PrivateKey
ToECDSA returns the private key as a *ecdsa.PrivateKey.
type PublicKey ¶
serialize in uncompressed, compressed, and hybrid formats.
func ParsePubKey ¶
func ParsePubKey(pubKeyStr []byte, curve *KoblitzCurve) (key *PublicKey, err error)
ParsePubKey parses a public key for a koblitz curve from a bytestring into a uncompressed and hybrid signature formats.
func RecoverCompact ¶
func RecoverCompact(curve *KoblitzCurve, signature, hash []byte) (*PublicKey, bool, error)
RecoverCompact verifies the compact signature "signature" of "hash" for the Koblitz curve in "curve". If the signature matches then the recovered public key will be returned as well as a boolen if the original key was compressed or not, else an error will be returned.
func (*PublicKey) IsEqual ¶
IsEqual compares this PublicKey instance to the one passed, returning true if both have the same X and Y coordinate.
func (*PublicKey) SerializeCompressed ¶
SerializeCompressed serializes a public key in a 33-byte compressed format.
func (*PublicKey) SerializeHybrid ¶
SerializeHybrid serializes a public key in a 65-byte hybrid format.
func (*PublicKey) SerializeUncompressed ¶
SerializeUncompressed serializes a public key in a 65-byte uncompressed format.
type Signature ¶
func ParseDERSignature ¶
ParseDERSignature parses a signature in DER format for the curve type `curve` into a Signature type. If parsing according to the less strict
func ParseSignature ¶
ParseSignature parses a signature in BER format for the curve type `curve' into a Signature type, perfoming some basic sanity checks. If parsing
func (*Signature) IsEqual ¶
IsEqual compares this Signature instance to the one passed, returning true they both have the same scalar value for R and S.
Source Files