def __init__(self, key, iv, do, ciphername='aes-256-cbc'):
"""
do == 1 => Encrypt; do == 0 => Decrypt
"""
self.cipher = OpenSSL.get_cipher(ciphername)
self.ctx = OpenSSL.EVP_CIPHER_CTX_new()
if do == 1 or do == 0:
k = OpenSSL.malloc(key, len(key))
IV = OpenSSL.malloc(iv, len(iv))
OpenSSL.EVP_CipherInit_ex(self.ctx, self.cipher.get_pointer(), 0,
k, IV, do)
else:
raise Exception("RTFM ...")
def decrypt(self, data, ciphername='aes-256-cbc'):
"""
Decrypt data with ECIES method using the local private key
"""
blocksize = OpenSSL.get_cipher(ciphername).get_blocksize()
iv = data[:blocksize]
i = blocksize
_, pubkey_x, pubkey_y, i2 = ECC._decode_pubkey(data[i:])
i += i2
ciphertext = data[i:len(data) - 32]
i += len(ciphertext)
mac = data[i:]
key = sha512(self.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
key_e, key_m = key[:32], key[32:]
if not equals(hmac_sha256(key_m, data[:len(data) - 32]), mac):
raise RuntimeError("Fail to verify data")
ctx = Cipher(key_e, iv, 0, ciphername)
return ctx.ciphering(ciphertext)
def raw_encrypt(
data,
pubkey_x,
pubkey_y,
curve='sect283r1',
ephemcurve=None,
ciphername='aes-256-cbc',
): # pylint: disable=too-many-arguments
"""ECHD encryption, keys supplied in binary data format"""
if ephemcurve is None:
ephemcurve = curve
ephem = ECC(curve=ephemcurve)
key = sha512(ephem.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
key_e, key_m = key[:32], key[32:]
pubkey = ephem.get_pubkey()
iv = OpenSSL.rand(OpenSSL.get_cipher(ciphername).get_blocksize())
ctx = Cipher(key_e, iv, 1, ciphername)
ciphertext = iv + pubkey + ctx.ciphering(data)
mac = hmac_sha256(key_m, ciphertext)
return ciphertext + mac
def gen_IV(ciphername):
"""Generate random initialization vector"""
cipher = OpenSSL.get_cipher(ciphername)
return OpenSSL.rand(cipher.get_blocksize())
def get_blocksize(ciphername):
"""This Method returns cipher blocksize"""
cipher = OpenSSL.get_cipher(ciphername)
return cipher.get_blocksize()
