started migration to optional hash/prime number specification

3 files changed, 294 insertions, 102 deletions

diff --git a/_ctsrp.py b/_ctsrp.py
index 4675591..93accf5 100644
--- a/_ctsrp.py
+++ b/_ctsrp.py
@@ -18,15 +18,75 @@ import sys
 import hashlib

 import random

 import ctypes

-import atexit

 import time

 

 

-SHA256_DIGEST_LENGTH = 32

 

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

-G_HEX  = "2"

-HNxorg = None

+SHA1   = 0

+SHA224 = 1

+SHA256 = 3

+SHA384 = 4

+SHA512 = 5

+

+NG_1024   = 0

+NG_2048   = 1

+NG_4096   = 2

+NG_CUSTOM = 3

+

+_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")

+)

+

+

+

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

+#G_HEX  = "2"

+#HNxorg = None

 

 dlls = list()

 

@@ -126,21 +186,21 @@ def bytes_to_bn( dest_bn, bytes ):
     BN_bin2bn(bytes, len(bytes), dest_bn)

     

  

-def H_str( dest_bn, s ):

-    d = hashlib.sha256(s).digest()

+def H_str( hash_class, dest_bn, s ):

+    d = hash_class(s).digest()

     buff = ctypes.create_string_buffer( s )

     BN_bin2bn(d, len(d), dest)

 

 

-def H_bn( dest, n ):

+def H_bn( hash_class, dest, n ):

     bin = ctypes.create_string_buffer( BN_num_bytes(n) )

     BN_bn2bin(n, bin)

-    d = hashlib.sha256( bin.raw ).digest()

+    d = hash_class( bin.raw ).digest()

     BN_bin2bn(d, len(d), dest)

     

     

-def H_bn_bn( dest, n1, n2 ):

-    h    = hashlib.sha256()

+def H_bn_bn( hash_class, dest, n1, n2 ):

+    h    = hash_class()

     bin1 = ctypes.create_string_buffer( BN_num_bytes(n1) )

     bin2 = ctypes.create_string_buffer( BN_num_bytes(n2) )

     BN_bn2bin(n1, bin1)

@@ -151,8 +211,8 @@ def H_bn_bn( dest, n1, n2 ):
     BN_bin2bn(d, len(d), dest)

     

     

-def H_bn_str( dest, n, s ):

-    h   = hashlib.sha256()

+def H_bn_str( hash_class, dest, n, s ):

+    h   = hash_class()

     bin = ctypes.create_string_buffer( BN_num_bytes(n) )

     BN_bn2bin(n, bin)

     h.update( bin.raw )

@@ -161,9 +221,9 @@ def H_bn_str( dest, n, s ):
     BN_bin2bn(d, len(d), dest)

  

     

-def calculate_x( dest, salt, username, password ):

-    up = hashlib.sha256('%s:%s' % (username, password )).digest()

-    H_bn_str( dest, salt, up )

+def calculate_x( hash_class, dest, salt, username, password ):

+    up = hash_class('%s:%s' % (username, password )).digest()

+    H_bn_str( hash_class, dest, salt, up )

     

     

 def update_hash( ctx, n ):

@@ -172,10 +232,10 @@ def update_hash( ctx, n ):
     ctx.update( buff.raw )

 

     

-def calculate_M( I, s, A, B, K ):

-    h = hashlib.sha256()

-    h.update( HNxorg )

-    h.update( hashlib.sha256(I).digest() )

+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() )

     update_hash( h, s )

     update_hash( h, A )

     update_hash( h, B )

@@ -183,38 +243,55 @@ def calculate_M( I, s, A, B, K ):
     return h.digest()

     

 

-def calculate_H_AMK( A, M, K ):

-    h = hashlib.sha256()

+def calculate_H_AMK( hash_class, A, M, K ):

+    h = hash_class()

     update_hash( h, A )

     h.update( M )

     h.update( K )

     return h.digest()

 

     

-def calculate_HN_xor_Hg():

-    global HNxorg

-    

+def HNxorg( hash_class, N, g ):    

     bN = ctypes.create_string_buffer( BN_num_bytes(N) )

     bg = ctypes.create_string_buffer( BN_num_bytes(g) )

     

     BN_bn2bin(N, bN)

     BN_bn2bin(g, bg)

     

-    hN = hashlib.sha256( bN.raw ).digest()

-    hg = hashlib.sha256( bg.raw ).digest()

+    hN = hash_class( bN.raw ).digest()

+    hg = hash_class( bg.raw ).digest()

     

-    HNxorg  = ''.join( chr( ord(hN[i]) ^ ord(hg[i]) ) for i in range(0,len(hN)) )

+    return ''.join( chr( ord(hN[i]) ^ ord(hg[i]) ) for i in range(0,len(hN)) )

+

+

+

+def get_ngk( hash_class, ng_type, n_hex, g_hex ):

+    if ng_type < NG_CUSTOM:

+        n_hex, g_hex = _ng_const[ ng_type ]

+    N = BN_new()

+    g = BN_new()

+    k = BN_new()

+    

+    BN_hex2bn( N, n_hex )

+    BN_hex2bn( g, g_hex )

+    H_bn_bn(hash_class, k, N, g)

+

+    return N, g, k

+

     

   

-def gen_sv( username, password ):

+def gen_sv( username, password, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None ):

     s    = BN_new()

     v    = BN_new()

     x    = BN_new()

     ctx  = BN_CTX_new()

+    

+    hash_class = _hash_map[ hash_alg ]

+    N,g,k      = get_ngk( hash_class, ng_type, n_hex, g_hex )

 

     BN_rand(s, 32, -1, 0);

         

-    calculate_x(x, s, username, password )

+    calculate_x( hash_class, x, s, username, password )

         

     BN_mod_exp(v, g, x, N, ctx)

     

@@ -224,6 +301,9 @@ def gen_sv( username, password ):
     BN_free(s)

     BN_free(v)

     BN_free(x)

+    BN_free(N)

+    BN_free(g)

+    BN_free(k)

     BN_CTX_free(ctx)

     

     return salt, verifier

@@ -231,7 +311,7 @@ def gen_sv( username, password ):
   

 

 class Verifier (object):

-    def __init__(self,  username, bytes_s, bytes_v, bytes_A):

+    def __init__(self,  username, bytes_s, bytes_v, bytes_A, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None):

         self.A     = BN_new()

         self.B     = BN_new()

         self.K     = None

@@ -250,6 +330,14 @@ class Verifier (object):
         

         self.safety_failed = False

         

+        hash_class = _hash_map[ hash_alg ]

+        N,g,k      = get_ngk( hash_class, ng_type, n_hex, g_hex )

+        

+        self.hash_class = hash_class

+        self.N          = N

+        self.g          = g

+        self.k          = k

+        

         bytes_to_bn( self.s, bytes_s )

         bytes_to_bn( self.v, bytes_v )        

         bytes_to_bn( self.A, bytes_A )

@@ -267,17 +355,17 @@ class Verifier (object):
             BN_mod_exp(self.tmp2, g, self.b, N, self.ctx)

             BN_add(self.B, self.tmp1, self.tmp2)

             

-            H_bn_bn(self.u, self.A, self.B)

+            H_bn_bn(hash_class, self.u, self.A, self.B)

             

             # S = (A *(v^u)) ^ b

             BN_mod_exp(self.tmp1, self.v, self.u, N, self.ctx)

             BN_mul(self.tmp2, self.A, self.tmp1, self.ctx)

             BN_mod_exp(self.S, self.tmp2, self.b, N, self.ctx)

             

-            self.K = hashlib.sha256( bn_to_bytes(self.S) ).digest()

+            self.K = hash_class( bn_to_bytes(self.S) ).digest()

             

-            self.M     = calculate_M( self.I, self.s, self.A, self.B, self.K )

-            self.H_AMK = calculate_H_AMK( self.A, self.M, self.K )

+            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 __del__(self):

@@ -288,6 +376,9 @@ class Verifier (object):
         BN_free(self.b)

         BN_free(self.s)

         BN_free(self.v)

+        BN_free(self.N)

+        BN_free(self.g)

+        BN_free(self.k)

         BN_free(self.tmp1)

         BN_free(self.tmp2)

         BN_CTX_free(self.ctx)

@@ -322,7 +413,7 @@ class Verifier (object):
         

     

 class User (object):

-    def __init__(self, username, password):

+    def __init__(self, username, password, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None):

         self.username = username

         self.password = password

         self.a     = BN_new()

@@ -342,6 +433,14 @@ class User (object):
         self.H_AMK = None

         self._authenticated = False

         

+        hash_class = _hash_map[ hash_alg ]

+        N,g,k      = get_ngk( hash_class, ng_type, n_hex, g_hex )

+        

+        self.hash_class = hash_class

+        self.N          = N

+        self.g          = g

+        self.k          = k

+        

         BN_rand(self.a, 256, -1, 0)

         

         BN_mod_exp(self.A, g, self.a, N, self.ctx)

@@ -356,6 +455,9 @@ class User (object):
         BN_free(self.u)

         BN_free(self.x)

         BN_free(self.v)

+        BN_free(self.N)

+        BN_free(self.g)

+        BN_free(self.k)

         BN_free(self.tmp1)

         BN_free(self.tmp2)

         BN_free(self.tmp3)

@@ -380,6 +482,11 @@ class User (object):
         

     # Returns M or None if SRP-6a safety check is violated

     def process_challenge(self, bytes_s, bytes_B):

+

+        hash_class = self.hash_class

+        N = self.N

+        g = self.g

+        k = self.k

         

         bytes_to_bn( self.s, bytes_s )

         bytes_to_bn( self.B, bytes_B )

@@ -388,13 +495,13 @@ class User (object):
         if BN_is_zero(self.B):

             return None

             

-        H_bn_bn(self.u, self.A, self.B)

+        H_bn_bn(hash_class, self.u, self.A, self.B)

         

         # SRP-6a safety check

         if BN_is_zero(self.u):

             return None

         

-        calculate_x( self.x, self.s, self.username, self.password )

+        calculate_x( hash_class, self.x, self.s, self.username, self.password )

         

         BN_mod_exp(self.v, g, self.x, N, self.ctx)

         

@@ -407,9 +514,9 @@ class User (object):
         BN_sub(self.tmp1, self.B, self.tmp3)            # tmp1 = (B - K*(g^x))

         BN_mod_exp(self.S, self.tmp1, self.tmp2, N, self.ctx)

 

-        self.K     = hashlib.sha256( bn_to_bytes(self.S) ).digest()

-        self.M     = calculate_M( self.username, self.s, self.A, self.B, self.K )

-        self.H_AMK = calculate_H_AMK( self.A, self.M, self.K )

+        self.K     = hash_class( bn_to_bytes(self.S) ).digest()

+        self.M     = calculate_M( hash_class, N, g, self.username, 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

         

@@ -417,26 +524,11 @@ class User (object):
     def verify_session(self, host_HAMK):

         if self.H_AMK == host_HAMK:

             self._authenticated = True

-        

+

+            

+

 #---------------------------------------------------------

 # Init

 #

-N      = BN_new()

-g      = BN_new()

-k      = BN_new()

-HNxorg = None

-

-BN_hex2bn( N, N_HEX )

-BN_hex2bn( g, G_HEX )

-H_bn_bn(k, N, g)

-

-calculate_HN_xor_Hg()

-

 RAND_seed( os.urandom(32), 32 )

 

-def cleanup():

-    BN_free( N )

-    BN_free( g )

-    BN_free( k )

-    

-atexit.register( cleanup )

diff --git a/_pysrp.py b/_pysrp.py
index 8a89e71..2050837 100644
--- a/_pysrp.py
+++ b/_pysrp.py
@@ -17,6 +17,71 @@ import hashlib
 import os
 import binascii
 
+SHA1   = 0
+SHA224 = 1
+SHA256 = 3
+SHA384 = 4
+SHA512 = 5
+
+NG_1024   = 0
+NG_2048   = 1
+NG_4096   = 2
+NG_CUSTOM = 3
+
+_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")
+)
+
+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])
@@ -42,7 +107,7 @@ def get_random( nbytes ):
     return bytes_to_long( os.urandom( nbytes ) )
 
     
-def old_H( s1, s2 = '', s3=''):
+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)):
@@ -50,11 +115,11 @@ def old_H( s1, s2 = '', s3=''):
     if s3 and isinstance(s3, (long, int)):
         s3 = long_to_bytes(s3)
     s = s1 + s2 + s3
-    return long(hashlib.sha256(s).hexdigest(), 16)
+    return long(hash_class(s).hexdigest(), 16)
     
     
-def H( *args, **kwargs ):
-    h = hashlib.sha256()
+def H( hash_class, *args, **kwargs ):
+    h = hash_class()
     
     for s in args:
         if s is not None:
@@ -64,35 +129,38 @@ def H( *args, **kwargs ):
 
 
 
-N = 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
-g = 2;    
-k = H(N,g)  
+#N = 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
+#g = 2;    
+#k = H(N,g)  
 
-hN = hashlib.sha256( long_to_bytes(N) ).digest()
-hg = hashlib.sha256( long_to_bytes(g) ).digest()
+def HNxorg( hash_class, N, g ):
+    hN = hash_class( long_to_bytes(N) ).digest()
+    hg = hash_class( long_to_bytes(g) ).digest()
 
-HNxorg  = ''.join( chr( ord(hN[i]) ^ ord(hg[i]) ) for i in range(0,len(hN)) )
+    return ''.join( chr( ord(hN[i]) ^ ord(hg[i]) ) for i in range(0,len(hN)) )
     
     
     
-def gen_x( salt, username, password ):
-    return H( salt, H( username + ':' + password ) )
+def gen_x( hash_class, salt, username, password ):
+    return H( hash_class, salt, H( hash_class, username + ':' + password ) )
     
     
     
     
-def gen_sv( username, password ):
+def gen_sv( username, password, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None ):
+    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( _s, username, password ), N) )
+    _v = long_to_bytes( pow(g,  gen_x( hash_class, _s, username, password ), N) )
     
     return _s, _v
     
 
     
-def calculate_M( I, s, A, B, K ):
-    h = hashlib.sha256()
-    h.update( HNxorg )
-    h.update( hashlib.sha256(I).digest() )
+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) )
@@ -100,8 +168,8 @@ def calculate_M( I, s, A, B, K ):
     return h.digest()
 
 
-def calculate_H_AMK( A, M, K ):
-    h = hashlib.sha256()
+def calculate_H_AMK( hash_class, A, M, K ):
+    h = hash_class()
     h.update( long_to_bytes(A) )
     h.update( M )
     h.update( K )
@@ -112,13 +180,22 @@ def calculate_H_AMK( A, M, K ):
   
 class Verifier (object):
   
-    def __init__(self, username, bytes_s, bytes_v, bytes_A):
+    def __init__(self, username, bytes_s, bytes_v, bytes_A, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None):
         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
@@ -128,11 +205,11 @@ class Verifier (object):
             
             self.b = get_random( 32 )
             self.B = (k*self.v + pow(g, self.b, N)) % N
-            self.u = H(self.A, self.B)
+            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 = hashlib.sha256( long_to_bytes(self.S) ).digest()
-            self.M = calculate_M( self.I, self.s, self.A, self.B, self.K )
-            self.H_AMK = calculate_H_AMK(self.A, self.M, self.K)
+            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):
@@ -163,7 +240,12 @@ class Verifier (object):
         
         
 class User (object):
-    def __init__(self, username, password):
+    def __init__(self, username, password, hash_alg=SHA1, ng_type=NG_1024, n_hex=None, g_hex=None):
+        
+        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 )
@@ -174,6 +256,11 @@ class User (object):
         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
@@ -197,25 +284,31 @@ class User (object):
         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( self.A, self.B )
+        self.u = H( hash_class, self.A, self.B )
         
         # SRP-6a safety check
         if self.u == 0:
             return None
         
-        self.x = gen_x( self.s, self.I, self.p )
+        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     = hashlib.sha256( long_to_bytes(self.S) ).digest()        
-        self.M     = calculate_M( self.I, self.s, self.A, self.B, self.K )
-        self.H_AMK = calculate_H_AMK(self.A, self.M, self.K)
+        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
         
diff --git a/test_srp.py b/test_srp.py
index cbfa54a..d833f74 100644
--- a/test_srp.py
+++ b/test_srp.py
@@ -1,6 +1,6 @@
 #!/usr/bin/python
 
-NTHREADS = 2
+NTHREADS = 1
 NTEST    = 10
 
 import _pysrp
@@ -9,16 +9,23 @@ Verifier = _pysrp.Verifier
 gen_sv   = _pysrp.gen_sv
 
 import _ctsrp
-#User     = _ctsrp.User
-#Verifier = _ctsrp.Verifier
-#gen_sv   = _ctsrp.gen_sv
-    
-import _srp
-#User     = _srp.User
-#Verifier = _srp.Verifier
-#gen_sv   = _srp.gen_sv
+User     = _ctsrp.User
+Verifier = _ctsrp.Verifier
+gen_sv   = _ctsrp.gen_sv
+
+try:
+    import _srp
+    #User     = _srp.User
+    #Verifier = _srp.Verifier
+    #gen_sv   = _srp.gen_sv
+except:
+    print 'C-module not available'
+    pass
 
 import srp
+
+HASH = _pysrp.SHA1
+NG   = _pysrp.NG_1024
 #User     = srp.User
 #Verifier = srp.Verifier
 #gen_sv   = srp.gen_sv
@@ -26,14 +33,14 @@ import srp
 username = 'testuser'
 password = 'testpassword'
 
-_s, _v = gen_sv( username, password )
+_s, _v = gen_sv( username, password, hash_alg=HASH, ng_type=NG )
     
 def test_one():
-    usr      = User( username, password )
+    usr      = User( username, password, hash_alg=HASH, ng_type=NG )
     uname, A = usr.start_authentication()
     
     # username, A => server
-    svr      = Verifier( uname, _s, _v, A )
+    svr      = Verifier( uname, _s, _v, A, hash_alg=HASH, ng_type=NG )
     s,B      = svr.get_challenge()
     
     # s,B => client