README
¶
ige
IGE block cipher mode for Go.
about
IGE is a block cipher mode usually used with AES. It's most notably used in Telegram's MTProto Protocol. It can be defined as the following function:
c_i = f_k(p_i ^ c_{i-1}) ^ p_{i-1}
c_iis ciphertext of theiblockp_iis plaintext of theiblockf_kis the block cipher function withkas the key
Here is a diagram of the above function:
Note that c_0 and m_0 in the diagram represent the initilization vectors. This implementation requires an initialization vector of two blocks. The first block is used as c_0. The second block is used as m_0.
testing
I'm using the test vectors described in the official OpenSSL IGE paper. You can execute the tests yourself by running:
$ go test
test vector 1
key
00010203 04050607 08090A0B 0C0D0E0F
initialization vector
00010203 04050607 08090A0B 0C0D0E0F
10111213 14151617 18191A1B 1C1D1E1F
plaintext
00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000
ciphertext
1A8519A6 557BE652 E9DA8E43 DA4EF445
3CF456B4 CA488AA3 83C79C98 B34797CB
test vector 2
key
54686973 20697320 616E2069 6D706C65
initialization vector
6D656E74 6174696F 6E206F66 20494745
206D6F64 6520666F 72204F70 656E5353
plaintext
99706487 A1CDE613 BC6DE0B6 F24B1C7A
A448C8B9 C3403E34 67A8CAD8 9340F53B
ciphertext
4C2E204C 65742773 20686F70 65204265
6E20676F 74206974 20726967 6874210A
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrInvalidIV = errors.New("iv length must be: (block size * 2)")
ErrInvalidIV is displayed as the panic message if the initialization vector passed to NewIGEEncrypter or NewIGEDecrypter doesn't fulfill the length requirements for IGE.
IGE uses a two step xor process, so the first initialization vector is the first half, and the second initialization vector is the second half. This requires the initialization vector to be twice as long as the block size.
Functions ¶
This section is empty.
Types ¶
type IGE ¶
type IGE interface {
// BlockSize returns the mode's block size.
BlockSize() int
// CryptBlocks encrypts or decrypts a number of blocks based on the
// underlying cipher.Block passed to NewIGEEncrypter or NewIGEDecrypter
// (usually from crypto/aes).
CryptBlocks(dst, src []byte)
}
IGE satisfies the cipher.BlockMode interface from the crypto/cipher package.
func NewIGEDecrypter ¶
NewIGEDecrypter returns an IGE cipher.BlockMode which decrypts using IGE and the given cipher.Block.
Note: iv must contain two iv values for IGE (concatenated), otherwise this function will panic. See ErrInvalidIV for more information.
func NewIGEEncrypter ¶
NewIGEEncrypter returns an IGE cipher.BlockMode which encrypts using IGE and the given cipher.Block.
Note: iv must contain two iv values for IGE (concatenated), otherwise this function will panic. See ErrInvalidIV for more information.
Source Files