func DecryptCBC(ciph cipher.Block, iv []byte, ciphertext []byte) ([]byte, error) {
var resultblocks [][]byte
blocks := mobytes.SplitEvery(ciphertext, 16)
for i, block := range blocks {
decrypted := make([]byte, 16)
ciph.Decrypt(decrypted, block)
if i == 0 {
decrypted = mobytes.XOR(decrypted, iv)
} else {
decrypted = mobytes.XOR(decrypted, blocks[i-1])
}
resultblocks = append(resultblocks, decrypted)
}
return bytes.Join(resultblocks, nil), nil
}
func DecryptCTR(ciph cipher.Block, iv []byte, ciphertext []byte) ([]byte, error) {
var pad []byte
var mixin big.Int
mixin.SetBytes(iv)
for i := 0; i <= len(ciphertext)/16; i++ {
if i != 0 {
mixin.Add(&mixin, big.NewInt(1)) // mixin++
}
encrypted := make([]byte, 16)
ciph.Encrypt(encrypted, mixin.Bytes())
pad = append(pad, encrypted...)
}
return mobytes.XOR(ciphertext, pad), nil
}