461 lines
18 KiB
Python
461 lines
18 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# Copyright (C) 2011 Yann GUIBET <yannguibet@gmail.com>
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# See LICENSE for details.
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from hashlib import sha512
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from pyelliptic.openssl import OpenSSL
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from pyelliptic.cipher import Cipher
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from pyelliptic.hash import hmac_sha256
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from struct import pack, unpack
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class ECC:
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"""
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Asymmetric encryption with Elliptic Curve Cryptography (ECC)
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ECDH, ECDSA and ECIES
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import pyelliptic
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alice = pyelliptic.ECC() # default curve: sect283r1
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bob = pyelliptic.ECC(curve='sect571r1')
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ciphertext = alice.encrypt("Hello Bob", bob.get_pubkey())
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print bob.decrypt(ciphertext)
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signature = bob.sign("Hello Alice")
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# alice's job :
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print pyelliptic.ECC(
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pubkey=bob.get_pubkey()).verify(signature, "Hello Alice")
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# ERROR !!!
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try:
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key = alice.get_ecdh_key(bob.get_pubkey())
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except: print("For ECDH key agreement,\
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the keys must be defined on the same curve !")
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alice = pyelliptic.ECC(curve='sect571r1')
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print alice.get_ecdh_key(bob.get_pubkey()).encode('hex')
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print bob.get_ecdh_key(alice.get_pubkey()).encode('hex')
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"""
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def __init__(self, pubkey=None, privkey=None, pubkey_x=None,
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pubkey_y=None, raw_privkey=None, curve='sect283r1'):
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"""
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For a normal and High level use, specifie pubkey,
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privkey (if you need) and the curve
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"""
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if type(curve) == str:
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self.curve = OpenSSL.get_curve(curve)
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else:
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self.curve = curve
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if pubkey_x is not None and pubkey_y is not None:
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self._set_keys(pubkey_x, pubkey_y, raw_privkey)
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elif pubkey is not None:
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curve, pubkey_x, pubkey_y, i = ECC._decode_pubkey(pubkey)
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if privkey is not None:
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curve2, raw_privkey, i = ECC._decode_privkey(privkey)
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if curve != curve2:
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raise Exception("Bad ECC keys ...")
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self.curve = curve
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self._set_keys(pubkey_x, pubkey_y, raw_privkey)
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else:
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self.privkey, self.pubkey_x, self.pubkey_y = self._generate()
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def _set_keys(self, pubkey_x, pubkey_y, privkey):
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if self.raw_check_key(privkey, pubkey_x, pubkey_y) < 0:
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self.pubkey_x = None
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self.pubkey_y = None
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self.privkey = None
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raise Exception("Bad ECC keys ...")
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else:
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self.pubkey_x = pubkey_x
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self.pubkey_y = pubkey_y
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self.privkey = privkey
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@staticmethod
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def get_curves():
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"""
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static method, returns the list of all the curves available
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"""
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return OpenSSL.curves.keys()
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def get_curve(self):
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return OpenSSL.get_curve_by_id(self.curve)
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def get_curve_id(self):
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return self.curve
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def get_pubkey(self):
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"""
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High level function which returns :
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curve(2) + len_of_pubkeyX(2) + pubkeyX + len_of_pubkeyY + pubkeyY
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"""
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return b''.join((pack('!H', self.curve),
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pack('!H', len(self.pubkey_x)),
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self.pubkey_x,
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pack('!H', len(self.pubkey_y)),
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self.pubkey_y
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))
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def get_privkey(self):
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"""
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High level function which returns
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curve(2) + len_of_privkey(2) + privkey
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"""
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return b''.join((pack('!H', self.curve),
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pack('!H', len(self.privkey)),
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self.privkey
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))
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@staticmethod
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def _decode_pubkey(pubkey):
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i = 0
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curve = unpack('!H', pubkey[i:i + 2])[0]
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i += 2
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tmplen = unpack('!H', pubkey[i:i + 2])[0]
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i += 2
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pubkey_x = pubkey[i:i + tmplen]
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i += tmplen
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tmplen = unpack('!H', pubkey[i:i + 2])[0]
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i += 2
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pubkey_y = pubkey[i:i + tmplen]
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i += tmplen
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return curve, pubkey_x, pubkey_y, i
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@staticmethod
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def _decode_privkey(privkey):
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i = 0
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curve = unpack('!H', privkey[i:i + 2])[0]
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i += 2
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tmplen = unpack('!H', privkey[i:i + 2])[0]
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i += 2
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privkey = privkey[i:i + tmplen]
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i += tmplen
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return curve, privkey, i
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def _generate(self):
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try:
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pub_key_x = OpenSSL.BN_new()
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pub_key_y = OpenSSL.BN_new()
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key = OpenSSL.EC_KEY_new_by_curve_name(self.curve)
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if key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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if (OpenSSL.EC_KEY_generate_key(key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_generate_key FAIL ...")
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if (OpenSSL.EC_KEY_check_key(key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
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priv_key = OpenSSL.EC_KEY_get0_private_key(key)
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group = OpenSSL.EC_KEY_get0_group(key)
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pub_key = OpenSSL.EC_KEY_get0_public_key(key)
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if (OpenSSL.EC_POINT_get_affine_coordinates_GFp(group, pub_key,
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pub_key_x,
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pub_key_y, 0
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)) == 0:
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raise Exception(
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"[OpenSSL] EC_POINT_get_affine_coordinates_GFp FAIL ...")
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privkey = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(priv_key))
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pubkeyx = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(pub_key_x))
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pubkeyy = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(pub_key_y))
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OpenSSL.BN_bn2bin(priv_key, privkey)
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privkey = privkey.raw
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OpenSSL.BN_bn2bin(pub_key_x, pubkeyx)
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pubkeyx = pubkeyx.raw
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OpenSSL.BN_bn2bin(pub_key_y, pubkeyy)
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pubkeyy = pubkeyy.raw
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self.raw_check_key(privkey, pubkeyx, pubkeyy)
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return privkey, pubkeyx, pubkeyy
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finally:
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OpenSSL.EC_KEY_free(key)
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OpenSSL.BN_free(pub_key_x)
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OpenSSL.BN_free(pub_key_y)
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def get_ecdh_key(self, pubkey):
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"""
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High level function. Compute public key with the local private key
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and returns a 512bits shared key
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"""
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curve, pubkey_x, pubkey_y, i = ECC._decode_pubkey(pubkey)
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if curve != self.curve:
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raise Exception("ECC keys must be from the same curve !")
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return sha512(self.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
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def raw_get_ecdh_key(self, pubkey_x, pubkey_y):
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try:
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ecdh_keybuffer = OpenSSL.malloc(0, 32)
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other_key = OpenSSL.EC_KEY_new_by_curve_name(self.curve)
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if other_key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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other_pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), 0)
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other_pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), 0)
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other_group = OpenSSL.EC_KEY_get0_group(other_key)
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other_pub_key = OpenSSL.EC_POINT_new(other_group)
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if (OpenSSL.EC_POINT_set_affine_coordinates_GFp(other_group,
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other_pub_key,
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other_pub_key_x,
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other_pub_key_y,
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0)) == 0:
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raise Exception(
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"[OpenSSL] EC_POINT_set_affine_coordinates_GFp FAIL ...")
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if (OpenSSL.EC_KEY_set_public_key(other_key, other_pub_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_public_key FAIL ...")
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if (OpenSSL.EC_KEY_check_key(other_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
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own_key = OpenSSL.EC_KEY_new_by_curve_name(self.curve)
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if own_key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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own_priv_key = OpenSSL.BN_bin2bn(
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self.privkey, len(self.privkey), 0)
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if (OpenSSL.EC_KEY_set_private_key(own_key, own_priv_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_private_key FAIL ...")
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OpenSSL.ECDH_set_method(own_key, OpenSSL.ECDH_OpenSSL())
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ecdh_keylen = OpenSSL.ECDH_compute_key(
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ecdh_keybuffer, 32, other_pub_key, own_key, 0)
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if ecdh_keylen != 32:
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raise Exception("[OpenSSL] ECDH keylen FAIL ...")
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return ecdh_keybuffer.raw
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finally:
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OpenSSL.EC_KEY_free(other_key)
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OpenSSL.BN_free(other_pub_key_x)
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OpenSSL.BN_free(other_pub_key_y)
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OpenSSL.EC_POINT_free(other_pub_key)
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OpenSSL.EC_KEY_free(own_key)
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OpenSSL.BN_free(own_priv_key)
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def check_key(self, privkey, pubkey):
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"""
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Check the public key and the private key.
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The private key is optional (replace by None)
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"""
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curve, pubkey_x, pubkey_y, i = ECC._decode_pubkey(pubkey)
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if privkey is None:
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raw_privkey = None
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curve2 = curve
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else:
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curve2, raw_privkey, i = ECC._decode_privkey(privkey)
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if curve != curve2:
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raise Exception("Bad public and private key")
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return self.raw_check_key(raw_privkey, pubkey_x, pubkey_y, curve)
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def raw_check_key(self, privkey, pubkey_x, pubkey_y, curve=None):
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if curve is None:
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curve = self.curve
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elif type(curve) == str:
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curve = OpenSSL.get_curve(curve)
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else:
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curve = curve
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try:
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key = OpenSSL.EC_KEY_new_by_curve_name(curve)
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if key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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if privkey is not None:
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priv_key = OpenSSL.BN_bin2bn(privkey, len(privkey), 0)
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pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), 0)
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pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), 0)
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if privkey is not None:
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if (OpenSSL.EC_KEY_set_private_key(key, priv_key)) == 0:
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raise Exception(
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"[OpenSSL] EC_KEY_set_private_key FAIL ...")
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group = OpenSSL.EC_KEY_get0_group(key)
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pub_key = OpenSSL.EC_POINT_new(group)
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if (OpenSSL.EC_POINT_set_affine_coordinates_GFp(group, pub_key,
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pub_key_x,
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pub_key_y,
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0)) == 0:
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raise Exception(
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"[OpenSSL] EC_POINT_set_affine_coordinates_GFp FAIL ...")
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if (OpenSSL.EC_KEY_set_public_key(key, pub_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_public_key FAIL ...")
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if (OpenSSL.EC_KEY_check_key(key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
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return 0
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finally:
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OpenSSL.EC_KEY_free(key)
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OpenSSL.BN_free(pub_key_x)
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OpenSSL.BN_free(pub_key_y)
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OpenSSL.EC_POINT_free(pub_key)
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if privkey is not None:
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OpenSSL.BN_free(priv_key)
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def sign(self, inputb):
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"""
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Sign the input with ECDSA method and returns the signature
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"""
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try:
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size = len(inputb)
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buff = OpenSSL.malloc(inputb, size)
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digest = OpenSSL.malloc(0, 64)
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md_ctx = OpenSSL.EVP_MD_CTX_create()
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dgst_len = OpenSSL.pointer(OpenSSL.c_int(0))
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siglen = OpenSSL.pointer(OpenSSL.c_int(0))
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sig = OpenSSL.malloc(0, 151)
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key = OpenSSL.EC_KEY_new_by_curve_name(self.curve)
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if key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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priv_key = OpenSSL.BN_bin2bn(self.privkey, len(self.privkey), 0)
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pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x), 0)
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pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y), 0)
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if (OpenSSL.EC_KEY_set_private_key(key, priv_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_private_key FAIL ...")
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group = OpenSSL.EC_KEY_get0_group(key)
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pub_key = OpenSSL.EC_POINT_new(group)
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if (OpenSSL.EC_POINT_set_affine_coordinates_GFp(group, pub_key,
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pub_key_x,
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pub_key_y,
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0)) == 0:
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raise Exception(
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"[OpenSSL] EC_POINT_set_affine_coordinates_GFp FAIL ...")
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if (OpenSSL.EC_KEY_set_public_key(key, pub_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_public_key FAIL ...")
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if (OpenSSL.EC_KEY_check_key(key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
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OpenSSL.EVP_MD_CTX_init(md_ctx)
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OpenSSL.EVP_DigestInit(md_ctx, OpenSSL.EVP_ecdsa())
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if (OpenSSL.EVP_DigestUpdate(md_ctx, buff, size)) == 0:
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raise Exception("[OpenSSL] EVP_DigestUpdate FAIL ...")
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OpenSSL.EVP_DigestFinal(md_ctx, digest, dgst_len)
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OpenSSL.ECDSA_sign(0, digest, dgst_len.contents, sig, siglen, key)
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if (OpenSSL.ECDSA_verify(0, digest, dgst_len.contents, sig,
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siglen.contents, key)) != 1:
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raise Exception("[OpenSSL] ECDSA_verify FAIL ...")
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return sig.raw[:siglen.contents.value]
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finally:
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OpenSSL.EC_KEY_free(key)
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OpenSSL.BN_free(pub_key_x)
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OpenSSL.BN_free(pub_key_y)
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OpenSSL.BN_free(priv_key)
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OpenSSL.EC_POINT_free(pub_key)
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OpenSSL.EVP_MD_CTX_destroy(md_ctx)
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def verify(self, sig, inputb):
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"""
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Verify the signature with the input and the local public key.
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Returns a boolean
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"""
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try:
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bsig = OpenSSL.malloc(sig, len(sig))
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binputb = OpenSSL.malloc(inputb, len(inputb))
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digest = OpenSSL.malloc(0, 64)
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dgst_len = OpenSSL.pointer(OpenSSL.c_int(0))
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md_ctx = OpenSSL.EVP_MD_CTX_create()
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key = OpenSSL.EC_KEY_new_by_curve_name(self.curve)
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if key == 0:
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raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
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pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x), 0)
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pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y), 0)
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group = OpenSSL.EC_KEY_get0_group(key)
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pub_key = OpenSSL.EC_POINT_new(group)
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if (OpenSSL.EC_POINT_set_affine_coordinates_GFp(group, pub_key,
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pub_key_x,
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pub_key_y,
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0)) == 0:
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raise Exception(
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"[OpenSSL] EC_POINT_set_affine_coordinates_GFp FAIL ...")
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if (OpenSSL.EC_KEY_set_public_key(key, pub_key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_set_public_key FAIL ...")
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if (OpenSSL.EC_KEY_check_key(key)) == 0:
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raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
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OpenSSL.EVP_MD_CTX_init(md_ctx)
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OpenSSL.EVP_DigestInit(md_ctx, OpenSSL.EVP_ecdsa())
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if (OpenSSL.EVP_DigestUpdate(md_ctx, binputb, len(inputb))) == 0:
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raise Exception("[OpenSSL] EVP_DigestUpdate FAIL ...")
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OpenSSL.EVP_DigestFinal(md_ctx, digest, dgst_len)
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ret = OpenSSL.ECDSA_verify(
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0, digest, dgst_len.contents, bsig, len(sig), key)
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if ret == -1:
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return False # Fail to Check
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else:
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if ret == 0:
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return False # Bad signature !
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else:
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return True # Good
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return False
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finally:
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OpenSSL.EC_KEY_free(key)
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OpenSSL.BN_free(pub_key_x)
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OpenSSL.BN_free(pub_key_y)
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OpenSSL.EC_POINT_free(pub_key)
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OpenSSL.EVP_MD_CTX_destroy(md_ctx)
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@staticmethod
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def encrypt(data, pubkey, ephemcurve=None, ciphername='aes-256-cbc'):
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"""
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Encrypt data with ECIES method using the public key of the recipient.
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"""
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curve, pubkey_x, pubkey_y, i = ECC._decode_pubkey(pubkey)
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return ECC.raw_encrypt(data, pubkey_x, pubkey_y, curve=curve,
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ephemcurve=ephemcurve, ciphername=ciphername)
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@staticmethod
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def raw_encrypt(data, pubkey_x, pubkey_y, curve='sect283r1',
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ephemcurve=None, ciphername='aes-256-cbc'):
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if ephemcurve is None:
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ephemcurve = curve
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ephem = ECC(curve=ephemcurve)
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key = sha512(ephem.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
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key_e, key_m = key[:32], key[32:]
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pubkey = ephem.get_pubkey()
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iv = OpenSSL.rand(OpenSSL.get_cipher(ciphername).get_blocksize())
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ctx = Cipher(key_e, iv, 1, ciphername)
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ciphertext = ctx.ciphering(data)
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mac = hmac_sha256(key_m, ciphertext)
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return iv + pubkey + ciphertext + mac
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def decrypt(self, data, ciphername='aes-256-cbc'):
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"""
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Decrypt data with ECIES method using the local private key
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"""
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blocksize = OpenSSL.get_cipher(ciphername).get_blocksize()
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iv = data[:blocksize]
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i = blocksize
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curve, pubkey_x, pubkey_y, i2 = ECC._decode_pubkey(data[i:])
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i += i2
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ciphertext = data[i:len(data)-32]
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i += len(ciphertext)
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mac = data[i:]
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key = sha512(self.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
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key_e, key_m = key[:32], key[32:]
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if hmac_sha256(key_m, ciphertext) != mac:
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raise RuntimeError("Fail to verify data")
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ctx = Cipher(key_e, iv, 0, ciphername)
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return ctx.ciphering(ciphertext)
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