40 lines
738 B
Go
40 lines
738 B
Go
package crypto
|
|
|
|
import (
|
|
"crypto/cipher"
|
|
"crypto/des"
|
|
)
|
|
|
|
var (
|
|
DerivationPurposeEnc = []byte{0x01, 0x82}
|
|
nullBytes8 = []byte{0, 0, 0, 0, 0, 0, 0, 0}
|
|
)
|
|
|
|
func DeriveKey(cardKey []byte, seq []byte, purpose []byte) ([]byte, error) {
|
|
key24 := resizeKey24(cardKey)
|
|
|
|
derivation := make([]byte, 16)
|
|
copy(derivation, purpose[:2])
|
|
copy(derivation[2:], seq[:2])
|
|
|
|
block, err := des.NewTripleDESCipher(key24)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
ciphertext := make([]byte, 16)
|
|
|
|
mode := cipher.NewCBCEncrypter(block, nullBytes8)
|
|
mode.CryptBlocks(ciphertext, derivation)
|
|
|
|
return ciphertext, nil
|
|
}
|
|
|
|
func resizeKey24(key []byte) []byte {
|
|
data := make([]byte, 24)
|
|
copy(data, key[0:16])
|
|
copy(data[16:], key[0:8])
|
|
|
|
return data
|
|
}
|