Merge pull request #704 from badmofo/ecies-encryption
replaced jackjack encryption with corrected ecies implementation
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commit
eb981926eb
133
lib/bitcoin.py
133
lib/bitcoin.py
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@ -383,21 +383,6 @@ def ECC_YfromX(x,curved=curve_secp256k1, odd=True):
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return [_p-My,offset]
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raise Exception('ECC_YfromX: No Y found')
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def private_header(msg,v):
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assert v<1, "Can't write version %d private header"%v
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r = ''
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if v==0:
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r += ('%08x'%len(msg)).decode('hex')
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r += sha256(msg)[:2]
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return ('%02x'%v).decode('hex') + ('%04x'%len(r)).decode('hex') + r
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def public_header(pubkey,v):
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assert v<1, "Can't write version %d public header"%v
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r = ''
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if v==0:
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r = sha256(pubkey)[:2]
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return '\x6a\x6a' + ('%02x'%v).decode('hex') + ('%04x'%len(r)).decode('hex') + r
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def negative_point(P):
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return Point( P.curve(), P.x(), -P.y(), P.order() )
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@ -493,83 +478,67 @@ class EC_KEY(object):
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raise Exception("Bad signature")
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# ecdsa encryption/decryption methods
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# credits: jackjack, https://github.com/jackjack-jj/jeeq
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# ecies encryption/decryption methods; aes-256-cbc is used as the cipher; hmac-sha256 is used as the mac
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@classmethod
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def encrypt_message(self, message, pubkey):
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generator = generator_secp256k1
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curved = curve_secp256k1
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r = ''
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msg = private_header(message,0) + message
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msg = msg + ('\x00'*( 32-(len(msg)%32) ))
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msgs = chunks(msg,32)
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_r = generator.order()
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str_to_long = string_to_number
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P = generator
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pk = ser_to_point(pubkey)
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if not ecdsa.ecdsa.point_is_valid(generator_secp256k1, pk.x(), pk.y()):
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raise Exception('invalid pubkey')
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ephemeral_exponent = number_to_string(ecdsa.util.randrange(pow(2,256)), generator_secp256k1.order())
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ephemeral = EC_KEY(ephemeral_exponent)
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ecdh_key = (pk * ephemeral.privkey.secret_multiplier).x()
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ecdh_key = ('%064x' % ecdh_key).decode('hex')
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key = hashlib.sha512(ecdh_key).digest()
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key_e, key_m = key[:32], key[32:]
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iv_ciphertext = aes.encryptData(key_e, message)
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for i in range(len(msgs)):
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n = ecdsa.util.randrange( pow(2,256) )
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Mx = str_to_long(msgs[i])
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My, xoffset = ECC_YfromX(Mx, curved)
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M = Point( curved, Mx+xoffset, My, _r )
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T = P*n
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U = pk*n + M
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toadd = point_to_ser(T) + point_to_ser(U)
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toadd = chr(ord(toadd[0])-2 + 2*xoffset) + toadd[1:]
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r += toadd
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ephemeral_pubkey = ephemeral.get_public_key(compressed=True).decode('hex')
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encrypted = 'BIE1' + hash_160(pubkey) + ephemeral_pubkey + iv_ciphertext
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mac = hmac.new(key_m, encrypted, hashlib.sha256).digest()
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return base64.b64encode(public_header(pubkey,0) + r)
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return base64.b64encode(encrypted + mac)
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def decrypt_message(self, enc):
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G = generator_secp256k1
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curved = curve_secp256k1
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pvk = self.secret
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pubkeys = [point_to_ser(G*pvk,True), point_to_ser(G*pvk,False)]
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enc = base64.b64decode(enc)
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str_to_long = string_to_number
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def decrypt_message(self, encrypted):
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encrypted = base64.b64decode(encrypted)
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if len(encrypted) < 105:
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raise Exception('invalid ciphertext: length')
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magic = encrypted[:4]
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recipient_pubkeyhash = encrypted[4:24]
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ephemeral_pubkey = encrypted[24:57]
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iv_ciphertext = encrypted[57:-32]
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mac = encrypted[-32:]
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if magic != 'BIE1':
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raise Exception('invalid ciphertext: invalid magic bytes')
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if hash_160(self.get_public_key().decode('hex')) != recipient_pubkeyhash:
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raise Exception('invalid ciphertext: invalid key')
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try:
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ephemeral_pubkey = ser_to_point(ephemeral_pubkey)
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except AssertionError, e:
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raise Exception('invalid ciphertext: invalid ephemeral pubkey')
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assert enc[:2]=='\x6a\x6a'
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phv = str_to_long(enc[2])
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assert phv==0, "Can't read version %d public header"%phv
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hs = str_to_long(enc[3:5])
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public_header=enc[5:5+hs]
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checksum_pubkey=public_header[:2]
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address=filter(lambda x:sha256(x)[:2]==checksum_pubkey, pubkeys)
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assert len(address)>0, 'Bad private key'
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address=address[0]
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enc=enc[5+hs:]
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r = ''
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for Tser,User in map(lambda x:[x[:33],x[33:]], chunks(enc,66)):
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ots = ord(Tser[0])
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xoffset = ots>>1
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Tser = chr(2+(ots&1))+Tser[1:]
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T = ser_to_point(Tser)
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U = ser_to_point(User)
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V = T*pvk
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Mcalc = U + negative_point(V)
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r += ('%064x'%(Mcalc.x()-xoffset)).decode('hex')
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pvhv = str_to_long(r[0])
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assert pvhv==0, "Can't read version %d private header"%pvhv
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phs = str_to_long(r[1:3])
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private_header = r[3:3+phs]
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size = str_to_long(private_header[:4])
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checksum = private_header[4:6]
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r = r[3+phs:]
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msg = r[:size]
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hashmsg = sha256(msg)[:2]
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checksumok = hashmsg==checksum
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return [msg, checksumok, address]
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if not ecdsa.ecdsa.point_is_valid(generator_secp256k1, ephemeral_pubkey.x(), ephemeral_pubkey.y()):
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raise Exception('invalid ciphertext: invalid ephemeral pubkey')
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ecdh_key = (ephemeral_pubkey * self.privkey.secret_multiplier).x()
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ecdh_key = ('%064x' % ecdh_key).decode('hex')
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key = hashlib.sha512(ecdh_key).digest()
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key_e, key_m = key[:32], key[32:]
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if mac != hmac.new(key_m, encrypted[:-32], hashlib.sha256).digest():
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raise Exception('invalid ciphertext: invalid mac')
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return aes.decryptData(key_e, iv_ciphertext)
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@ -779,7 +748,7 @@ def test_crypto():
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if __name__ == '__main__':
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#test_crypto()
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test_crypto()
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test_bip32("000102030405060708090a0b0c0d0e0f", "m/0'/1/2'/2/1000000000")
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test_bip32("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542","m/0/2147483647'/1/2147483646'/2")
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