// DecryptAes128Cbc decrypts the input using AES-128 in ECB mode, with
// the given key and initialization vector, assuming it was padded
// according to PKCS#7.
func DecryptAes128Cbc(input []byte, key []byte, iv []byte) []byte {
output := make([]byte, 0, len(input))
prevBlock := iv
for i := 0; i < len(input); i += aes.BlockSize {
// XOR with previous block (or IV) after decrypting
inputBlock := input[i : i+aes.BlockSize]
decryptedBlock := set1.DecryptAes128Ecb(inputBlock, key)
for i := 0; i < len(decryptedBlock); i++ {
decryptedBlock[i] ^= prevBlock[i]
}
output = append(output, decryptedBlock...)
prevBlock = inputBlock
}
return Pkcs7Unpad(output)
}
func (s *MySuite) TestEncryptAes128Ecb(c *C) {
key := []byte("YELLOW SUBMARINE")
text := []byte("This is a test!!")
// key length be at least 16
c.Assert(func() { EncryptAes128EcbWholeBlocks([]byte(text), key[:15]) },
PanicMatches, ".*")
// input length must be whole number of blocks
c.Assert(func() { EncryptAes128EcbWholeBlocks(text[:15], key) },
PanicMatches, ".*")
c.Assert(func() { EncryptAes128EcbWholeBlocks(append(text, byte(1)), key) },
PanicMatches, ".*")
c.Assert(EncryptAes128EcbWholeBlocks([]byte{}, key), DeepEquals, []byte{})
doubleText := append(text, text...)
c.Assert(set1.DecryptAes128Ecb(EncryptAes128EcbWholeBlocks(doubleText, key), key),
DeepEquals, doubleText)
}
