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Diffstat (limited to 'srp/_pysrp.py')
| -rw-r--r-- | srp/_pysrp.py | 364 |
1 files changed, 364 insertions, 0 deletions
diff --git a/srp/_pysrp.py b/srp/_pysrp.py new file mode 100644 index 0000000..ff907ea --- /dev/null +++ b/srp/_pysrp.py @@ -0,0 +1,364 @@ + # N A large safe prime (N = 2q+1, where q is prime) + # All arithmetic is done modulo N. + # g A generator modulo N + # k Multiplier parameter (k = H(N, g) in SRP-6a, k = 3 for legacy SRP-6) + # s User's salt + # I Username + # p Cleartext Password + # H() One-way hash function + # ^ (Modular) Exponentiation + # u Random scrambling parameter + # a,b Secret ephemeral values + # A,B Public ephemeral values + # x Private key (derived from p and s) + # v Password verifier + +import hashlib +import os +import binascii + +SHA1 = 0 +SHA224 = 1 +SHA256 = 2 +SHA384 = 3 +SHA512 = 4 + +NG_1024 = 0 +NG_2048 = 1 +NG_4096 = 2 +NG_8192 = 3 +NG_CUSTOM = 4 + +_hash_map = { SHA1 : hashlib.sha1, + SHA224 : hashlib.sha224, + SHA256 : hashlib.sha256, + SHA384 : hashlib.sha384, + SHA512 : hashlib.sha512 } + + +_ng_const = ( +# 1024-bit +('''\ +EEAF0AB9ADB38DD69C33F80AFA8FC5E86072618775FF3C0B9EA2314C9C256576D674DF7496\ +EA81D3383B4813D692C6E0E0D5D8E250B98BE48E495C1D6089DAD15DC7D7B46154D6B6CE8E\ +F4AD69B15D4982559B297BCF1885C529F566660E57EC68EDBC3C05726CC02FD4CBF4976EAA\ +9AFD5138FE8376435B9FC61D2FC0EB06E3''', +"2"), +# 2048 +('''\ +AC6BDB41324A9A9BF166DE5E1389582FAF72B6651987EE07FC3192943DB56050A37329CBB4\ +A099ED8193E0757767A13DD52312AB4B03310DCD7F48A9DA04FD50E8083969EDB767B0CF60\ +95179A163AB3661A05FBD5FAAAE82918A9962F0B93B855F97993EC975EEAA80D740ADBF4FF\ +747359D041D5C33EA71D281E446B14773BCA97B43A23FB801676BD207A436C6481F1D2B907\ +8717461A5B9D32E688F87748544523B524B0D57D5EA77A2775D2ECFA032CFBDBF52FB37861\ +60279004E57AE6AF874E7303CE53299CCC041C7BC308D82A5698F3A8D0C38271AE35F8E9DB\ +FBB694B5C803D89F7AE435DE236D525F54759B65E372FCD68EF20FA7111F9E4AFF73''', +"2"), +# 4096 +('''\ +FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E08\ +8A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B\ +302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9\ +A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE6\ +49286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8\ +FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D\ +670C354E4ABC9804F1746C08CA18217C32905E462E36CE3BE39E772C\ +180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF695581718\ +3995497CEA956AE515D2261898FA051015728E5A8AAAC42DAD33170D\ +04507A33A85521ABDF1CBA64ECFB850458DBEF0A8AEA71575D060C7D\ +B3970F85A6E1E4C7ABF5AE8CDB0933D71E8C94E04A25619DCEE3D226\ +1AD2EE6BF12FFA06D98A0864D87602733EC86A64521F2B18177B200C\ +BBE117577A615D6C770988C0BAD946E208E24FA074E5AB3143DB5BFC\ +E0FD108E4B82D120A92108011A723C12A787E6D788719A10BDBA5B26\ +99C327186AF4E23C1A946834B6150BDA2583E9CA2AD44CE8DBBBC2DB\ +04DE8EF92E8EFC141FBECAA6287C59474E6BC05D99B2964FA090C3A2\ +233BA186515BE7ED1F612970CEE2D7AFB81BDD762170481CD0069127\ +D5B05AA993B4EA988D8FDDC186FFB7DC90A6C08F4DF435C934063199\ +FFFFFFFFFFFFFFFF''', +"5"), +# 8192 +('''\ +FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E08\ +8A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B\ +302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9\ +A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE6\ +49286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8\ +FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D\ +670C354E4ABC9804F1746C08CA18217C32905E462E36CE3BE39E772C\ +180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF695581718\ +3995497CEA956AE515D2261898FA051015728E5A8AAAC42DAD33170D\ +04507A33A85521ABDF1CBA64ECFB850458DBEF0A8AEA71575D060C7D\ +B3970F85A6E1E4C7ABF5AE8CDB0933D71E8C94E04A25619DCEE3D226\ +1AD2EE6BF12FFA06D98A0864D87602733EC86A64521F2B18177B200C\ +BBE117577A615D6C770988C0BAD946E208E24FA074E5AB3143DB5BFC\ +E0FD108E4B82D120A92108011A723C12A787E6D788719A10BDBA5B26\ +99C327186AF4E23C1A946834B6150BDA2583E9CA2AD44CE8DBBBC2DB\ +04DE8EF92E8EFC141FBECAA6287C59474E6BC05D99B2964FA090C3A2\ +233BA186515BE7ED1F612970CEE2D7AFB81BDD762170481CD0069127\ +D5B05AA993B4EA988D8FDDC186FFB7DC90A6C08F4DF435C934028492\ +36C3FAB4D27C7026C1D4DCB2602646DEC9751E763DBA37BDF8FF9406\ +AD9E530EE5DB382F413001AEB06A53ED9027D831179727B0865A8918\ +DA3EDBEBCF9B14ED44CE6CBACED4BB1BDB7F1447E6CC254B33205151\ +2BD7AF426FB8F401378CD2BF5983CA01C64B92ECF032EA15D1721D03\ +F482D7CE6E74FEF6D55E702F46980C82B5A84031900B1C9E59E7C97F\ +BEC7E8F323A97A7E36CC88BE0F1D45B7FF585AC54BD407B22B4154AA\ +CC8F6D7EBF48E1D814CC5ED20F8037E0A79715EEF29BE32806A1D58B\ +B7C5DA76F550AA3D8A1FBFF0EB19CCB1A313D55CDA56C9EC2EF29632\ +387FE8D76E3C0468043E8F663F4860EE12BF2D5B0B7474D6E694F91E\ +6DBE115974A3926F12FEE5E438777CB6A932DF8CD8BEC4D073B931BA\ +3BC832B68D9DD300741FA7BF8AFC47ED2576F6936BA424663AAB639C\ +5AE4F5683423B4742BF1C978238F16CBE39D652DE3FDB8BEFC848AD9\ +22222E04A4037C0713EB57A81A23F0C73473FC646CEA306B4BCBC886\ +2F8385DDFA9D4B7FA2C087E879683303ED5BDD3A062B3CF5B3A278A6\ +6D2A13F83F44F82DDF310EE074AB6A364597E899A0255DC164F31CC5\ +0846851DF9AB48195DED7EA1B1D510BD7EE74D73FAF36BC31ECFA268\ +359046F4EB879F924009438B481C6CD7889A002ED5EE382BC9190DA6\ +FC026E479558E4475677E9AA9E3050E2765694DFC81F56E880B96E71\ +60C980DD98EDD3DFFFFFFFFFFFFFFFFF''', +'0x13') +) + +def get_ng( ng_type, n_hex, g_hex ): + if ng_type < NG_CUSTOM: + n_hex, g_hex = _ng_const[ ng_type ] + return int(n_hex,16), int(g_hex,16) + + +def bytes_to_long(s): + n = ord(s[0]) + for b in ( ord(x) for x in s[1:] ): + n = (n << 8) | b + return n + + +def long_to_bytes(n): + l = list() + x = 0 + off = 0 + while x != n: + b = (n >> off) & 0xFF + l.append( chr(b) ) + x = x | (b << off) + off += 8 + l.reverse() + return ''.join(l) + + +def get_random( nbytes ): + return bytes_to_long( os.urandom( nbytes ) ) + + +def old_H( hash_class, s1, s2 = '', s3=''): + if isinstance(s1, (long, int)): + s1 = long_to_bytes(s1) + if s2 and isinstance(s2, (long, int)): + s2 = long_to_bytes(s2) + if s3 and isinstance(s3, (long, int)): + s3 = long_to_bytes(s3) + s = s1 + s2 + s3 + return long(hash_class(s).hexdigest(), 16) + + +def H( hash_class, *args, **kwargs ): + h = hash_class() + + for s in args: + if s is not None: + h.update( long_to_bytes(s) if isinstance(s, (long, int)) else s ) + + return long( h.hexdigest(), 16 ) + + + +#N = 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g = 2; +#k = H(N,g) + +def HNxorg( hash_class, N, g ): + hN = hash_class( long_to_bytes(N) ).digest() + hg = hash_class( long_to_bytes(g) ).digest() + + return ''.join( chr( ord(hN[i]) ^ ord(hg[i]) ) for i in range(0,len(hN)) ) + + + +def gen_x( hash_class, salt, username, password ): + return H( hash_class, salt, H( hash_class, username + ':' + password ) ) + + + + +def create_salted_verification_key( username, password, hash_alg=SHA1, ng_type=NG_2048, n_hex=None, g_hex=None ): + if ng_type == NG_CUSTOM and (n_hex is None or g_hex is None): + raise ValueError("Both n_hex and g_hex are required when ng_type = NG_CUSTOM") + hash_class = _hash_map[ hash_alg ] + N,g = get_ng( ng_type, n_hex, g_hex ) + _s = long_to_bytes( get_random( 4 ) ) + _v = long_to_bytes( pow(g, gen_x( hash_class, _s, username, password ), N) ) + + return _s, _v + + + +def calculate_M( hash_class, N, g, I, s, A, B, K ): + h = hash_class() + h.update( HNxorg( hash_class, N, g ) ) + h.update( hash_class(I).digest() ) + h.update( long_to_bytes(s) ) + h.update( long_to_bytes(A) ) + h.update( long_to_bytes(B) ) + h.update( K ) + return h.digest() + + +def calculate_H_AMK( hash_class, A, M, K ): + h = hash_class() + h.update( long_to_bytes(A) ) + h.update( M ) + h.update( K ) + return h.digest() + + + + +class Verifier (object): + + def __init__(self, username, bytes_s, bytes_v, bytes_A, hash_alg=SHA1, ng_type=NG_2048, n_hex=None, g_hex=None): + if ng_type == NG_CUSTOM and (n_hex is None or g_hex is None): + raise ValueError("Both n_hex and g_hex are required when ng_type = NG_CUSTOM") + self.s = bytes_to_long(bytes_s) + self.v = bytes_to_long(bytes_v) + self.I = username + self.K = None + self._authenticated = False + + N,g = get_ng( ng_type, n_hex, g_hex ) + hash_class = _hash_map[ hash_alg ] + k = H( hash_class, N, g ) + + self.hash_class = hash_class + self.N = N + self.g = g + self.k = k + + self.A = bytes_to_long(bytes_A) + + # SRP-6a safety check + self.safety_failed = self.A % N == 0 + + if not self.safety_failed: + + self.b = get_random( 32 ) + self.B = (k*self.v + pow(g, self.b, N)) % N + self.u = H(hash_class, self.A, self.B) + self.S = pow(self.A*pow(self.v, self.u, N ), self.b, N) + self.K = hash_class( long_to_bytes(self.S) ).digest() + self.M = calculate_M( hash_class, N, g, self.I, self.s, self.A, self.B, self.K ) + self.H_AMK = calculate_H_AMK( hash_class, self.A, self.M, self.K ) + + + def authenticated(self): + return self._authenticated + + + def get_username(self): + return self.I + + + def get_session_key(self): + return self.K if self._authenticated else None + + # returns (bytes_s, bytes_B) on success, (None,None) if SRP-6a safety check fails + def get_challenge(self): + if self.safety_failed: + return None,None + else: + return (long_to_bytes(self.s), long_to_bytes(self.B)) + + # returns H_AMK on success, None on failure + def verify_session(self, user_M): + if not self.safety_failed and user_M == self.M: + self._authenticated = True + return self.H_AMK + + + + +class User (object): + def __init__(self, username, password, hash_alg=SHA1, ng_type=NG_2048, n_hex=None, g_hex=None): + if ng_type == NG_CUSTOM and (n_hex is None or g_hex is None): + raise ValueError("Both n_hex and g_hex are required when ng_type = NG_CUSTOM") + N,g = get_ng( ng_type, n_hex, g_hex ) + hash_class = _hash_map[ hash_alg ] + k = H( hash_class, N, g ) + + self.I = username + self.p = password + self.a = get_random( 32 ) + self.A = pow(g, self.a, N) + self.v = None + self.M = None + self.K = None + self.H_AMK = None + self._authenticated = False + + self.hash_class = hash_class + self.N = N + self.g = g + self.k = k + + + def authenticated(self): + return self._authenticated + + + def get_username(self): + return self.username + + + def get_session_key(self): + return self.K if self._authenticated else None + + + def start_authentication(self): + return (self.I, long_to_bytes(self.A)) + + + # Returns M or None if SRP-6a safety check is violated + def process_challenge(self, bytes_s, bytes_B): + + self.s = bytes_to_long( bytes_s ) + self.B = bytes_to_long( bytes_B ) + + N = self.N + g = self.g + k = self.k + + hash_class = self.hash_class + + # SRP-6a safety check + if (self.B % N) == 0: + return None + + self.u = H( hash_class, self.A, self.B ) + + # SRP-6a safety check + if self.u == 0: + return None + + self.x = gen_x( hash_class, self.s, self.I, self.p ) + + self.v = pow(g, self.x, N) + + self.S = pow((self.B - k*self.v), (self.a + self.u*self.x), N) + + self.K = hash_class( long_to_bytes(self.S) ).digest() + self.M = calculate_M( hash_class, N, g, self.I, self.s, self.A, self.B, self.K ) + self.H_AMK = calculate_H_AMK(hash_class, self.A, self.M, self.K) + + return self.M + + + def verify_session(self, host_HAMK): + if self.H_AMK == host_HAMK: + self._authenticated = True |