diff options
author | Tom Cocagne (vubuntu) <devnull@localhost> | 2010-08-30 23:37:47 -0400 |
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committer | Tom Cocagne (vubuntu) <devnull@localhost> | 2010-08-30 23:37:47 -0400 |
commit | 39fe54427deddfb11dea6209496b5bcdcaaadd05 (patch) | |
tree | 04b44b2f39c60b4585e8a41f59482a02c374bec2 /_srp.c |
initial commit
Diffstat (limited to '_srp.c')
-rw-r--r-- | _srp.c | 1137 |
1 files changed, 1137 insertions, 0 deletions
@@ -0,0 +1,1137 @@ +#include <Python.h> +#include <stdlib.h> +#include <string.h> +#include <stdio.h> + +#include <openssl/bn.h> +#include <openssl/sha.h> +#include <openssl/crypto.h> +#include <openssl/rand.h> + +/* 2048-bit prime & generator pair from RFC 5054 */ +#define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define G_HEX "2" + + +static const BIGNUM * N = 0; +static const BIGNUM * g = 0; +static const BIGNUM * k = 0; + + +struct SRPVerifier +{ + const char * username; + const unsigned char * bytes_B; + int authenticated; + + unsigned char M [SHA256_DIGEST_LENGTH]; + unsigned char H_AMK [SHA256_DIGEST_LENGTH]; + unsigned char session_key [SHA256_DIGEST_LENGTH]; +}; + + +struct SRPUser +{ + BIGNUM *a; + BIGNUM *A; + BIGNUM *S; + + const unsigned char * bytes_A; + int authenticated; + + const char * username; + const unsigned char * password; + int password_len; + + unsigned char M [SHA256_DIGEST_LENGTH]; + unsigned char H_AMK [SHA256_DIGEST_LENGTH]; + unsigned char session_key [SHA256_DIGEST_LENGTH]; +}; + + +/****************************************************************************** + * + * SRP Internal Helper Functions + * + *****************************************************************************/ + +/* +static BIGNUM * H_s( const char * s ) +{ + unsigned char buff[ SHA256_DIGEST_LENGTH ]; + SHA256( (const unsigned char *)s, strlen(s), buff ); + return BN_bin2bn(buff, SHA256_DIGEST_LENGTH, NULL); +} + + +static BIGNUM * H_n( const BIGNUM * n ) +{ + unsigned char buff[ SHA256_DIGEST_LENGTH ]; + int nbytes = BN_num_bytes(n); + unsigned char * bin = (unsigned char *) malloc( nbytes ); + BN_bn2bin(n, bin); + SHA256( bin, nbytes, buff ); + free(bin); + return BN_bin2bn(buff, SHA256_DIGEST_LENGTH, NULL); +} +*/ + +static BIGNUM * H_nn( const BIGNUM * n1, const BIGNUM * n2 ) +{ + unsigned char buff[ SHA256_DIGEST_LENGTH ]; + int len_n1 = BN_num_bytes(n1); + int len_n2 = BN_num_bytes(n2); + int nbytes = len_n1 + len_n2; + unsigned char * bin = (unsigned char *) malloc( nbytes ); + BN_bn2bin(n1, bin); + BN_bn2bin(n2, bin + len_n1); + SHA256( bin, nbytes, buff ); + free(bin); + return BN_bin2bn(buff, SHA256_DIGEST_LENGTH, NULL); +} + + +static BIGNUM * H_ns( const BIGNUM * n, + const unsigned char * bytes, + int len_bytes ) +{ + unsigned char buff[ SHA256_DIGEST_LENGTH ]; + int len_n = BN_num_bytes(n); + int nbytes = len_n + len_bytes; + unsigned char * bin = (unsigned char *) malloc( nbytes ); + BN_bn2bin(n, bin); + memcpy( bin + len_n, bytes, len_bytes ); + SHA256( bin, nbytes, buff ); + free(bin); + return BN_bin2bn(buff, SHA256_DIGEST_LENGTH, NULL); +} + + +static BIGNUM * calculate_x( const BIGNUM * salt, + const char * username, + const unsigned char * password, + int password_len ) +{ + unsigned char ucp_hash[SHA256_DIGEST_LENGTH]; + SHA256_CTX ctx; + + SHA256_Init( &ctx ); + + SHA256_Update( &ctx, username, strlen(username) ); + SHA256_Update( &ctx, ":", 1 ); + SHA256_Update( &ctx, password, password_len ); + + SHA256_Final( ucp_hash, &ctx ); + + return H_ns( salt, ucp_hash, sizeof(ucp_hash) ); +} + + +static void update_hash( SHA256_CTX *ctx, const BIGNUM * n ) +{ + unsigned long len = BN_num_bytes(n); + unsigned char * n_bytes = (unsigned char *) malloc( len ); + BN_bn2bin(n, n_bytes); + SHA256_Update(ctx, n_bytes, len); + free( n_bytes ); +} + + +static void hash_num( const BIGNUM * n, unsigned char * dest ) +{ + int nbytes = BN_num_bytes(n); + unsigned char * bin = (unsigned char *) malloc( nbytes ); + BN_bn2bin(n, bin); + SHA256( bin, nbytes, dest ); + free( bin ); +} + + +static void calculate_M( unsigned char * dest, + const char * I, + const BIGNUM * s, + const BIGNUM * A, + const BIGNUM * B, + const unsigned char * K ) +{ + unsigned char H_N[ SHA256_DIGEST_LENGTH ]; + unsigned char H_g[ SHA256_DIGEST_LENGTH ]; + unsigned char H_I[ SHA256_DIGEST_LENGTH ]; + unsigned char H_xor[ SHA256_DIGEST_LENGTH ]; + SHA256_CTX ctx; + int i = 0; + + hash_num( N, H_N ); + hash_num( g, H_g ); + + SHA256((const unsigned char *)I, strlen(I), H_I); + + for (i=0; i < SHA256_DIGEST_LENGTH; i++ ) + H_xor[i] = H_N[i] ^ H_g[i]; + + SHA256_Init( &ctx ); + + SHA256_Update( &ctx, H_xor, sizeof(H_xor) ); + SHA256_Update( &ctx, H_I, sizeof(H_I) ); + update_hash( &ctx, s ); + update_hash( &ctx, A ); + update_hash( &ctx, B ); + SHA256_Update( &ctx, K, SHA256_DIGEST_LENGTH ); + + SHA256_Final( dest, &ctx ); +} + + +static void calculate_H_AMK( unsigned char * dest, + const BIGNUM * A, + const unsigned char * M, + const unsigned char * K ) +{ + SHA256_CTX ctx; + + SHA256_Init( &ctx ); + + update_hash( &ctx, A ); + SHA256_Update( &ctx, M, SHA256_DIGEST_LENGTH); + SHA256_Update( &ctx, K, SHA256_DIGEST_LENGTH); + + SHA256_Final( dest, &ctx ); +} + + +/****************************************************************************** + * + * SRP "external" API + * + *****************************************************************************/ + +static void srp_init( const char * random_seed, int seed_len ) +{ + BIGNUM *tN = BN_new(); + BIGNUM *tg = BN_new(); + + BN_hex2bn( &tN, N_HEX ); + BN_hex2bn( &tg, G_HEX ); + + N = tN; + g = tg; + + k = H_nn(N,g); + + RAND_seed( random_seed, seed_len ); +} + +static void srp_fini( void ) +{ + BN_free((BIGNUM *)N); + BN_free((BIGNUM *)g); + BN_free((BIGNUM *)k); + + N = 0; + g = 0; +} + + +static void srp_gen_sv( const char * username, + const unsigned char * password, int len_password, + const unsigned char ** bytes_s, int * len_s, + const unsigned char ** bytes_v, int * len_v ) +{ + BIGNUM * s = BN_new(); + BIGNUM * v = BN_new(); + BIGNUM * x = 0; + BN_CTX *ctx = BN_CTX_new(); + + BN_rand(s, 32, -1, 0); + + x = calculate_x( s, username, password, len_password ); + + BN_mod_exp(v, g, x, N, ctx); + + *len_s = BN_num_bytes(s); + *len_v = BN_num_bytes(v); + + *bytes_s = (const unsigned char *) malloc( *len_s ); + *bytes_v = (const unsigned char *) malloc( *len_v ); + + BN_bn2bin(s, (unsigned char *) *bytes_s); + BN_bn2bin(v, (unsigned char *) *bytes_v); + + BN_free(s); + BN_free(v); + BN_free(x); + BN_CTX_free(ctx); +} + + +/* Out: bytes_B, len_B. + * + * On failure, bytes_B will be set to NULL and len_B will be set to 0 + */ +static struct SRPVerifier * srp_verifier_new( const char * username, + const unsigned char * bytes_s, int len_s, + const unsigned char * bytes_v, int len_v, + const unsigned char * bytes_A, int len_A, + const unsigned char ** bytes_B, int * len_B) +{ + BIGNUM *s = BN_bin2bn(bytes_s, len_s, NULL); + BIGNUM *v = BN_bin2bn(bytes_v, len_v, NULL); + BIGNUM *A = BN_bin2bn(bytes_A, len_A, NULL); + BIGNUM *u = 0; + BIGNUM *B = BN_new(); + BIGNUM *S = BN_new(); + BIGNUM *b = BN_new(); + BIGNUM *tmp1 = BN_new(); + BIGNUM *tmp2 = BN_new(); + BN_CTX *ctx = BN_CTX_new(); + int ulen = strlen(username) + 1; + + struct SRPVerifier * ver; + + ver = (struct SRPVerifier *) malloc( sizeof(struct SRPVerifier) ); + + ver->username = (char *) malloc( ulen ); + + memcpy( (char*)ver->username, username, ulen ); + + ver->authenticated = 0; + + /* SRP-6a safety check */ + BN_mod(tmp1, A, N, ctx); + if ( !BN_is_zero(tmp1) ) + { + BN_rand(b, 256, -1, 0); + + /* B = kv + g^b */ + BN_mul(tmp1, k, v, ctx); + BN_mod_exp(tmp2, g, b, N, ctx); + BN_add(B, tmp1, tmp2); + + u = H_nn(A,B); + + /* S = (A *(v^u)) ^ b */ + BN_mod_exp(tmp1, v, u, N, ctx); + BN_mul(tmp2, A, tmp1, ctx); + BN_mod_exp(S, tmp2, b, N, ctx); + + hash_num(S, ver->session_key); + + calculate_M( ver->M, username, s, A, B, ver->session_key ); + calculate_H_AMK( ver->H_AMK, A, ver->M, ver->session_key ); + + *len_B = BN_num_bytes(B); + *bytes_B = malloc( *len_B ); + + BN_bn2bin( B, (unsigned char *) *bytes_B ); + + ver->bytes_B = *bytes_B; + } + else + { + *len_B = 0; + *bytes_B = NULL; + } + + BN_free(s); + BN_free(v); + BN_free(A); + if (u) BN_free(u); + BN_free(B); + BN_free(S); + BN_free(b); + BN_free(tmp1); + BN_free(tmp2); + BN_CTX_free(ctx); + + return ver; +} + + +static void srp_verifier_delete( struct SRPVerifier * ver ) +{ + free( (char *) ver->username ); + free( (unsigned char *) ver->bytes_B ); + free( ver ); +} + + +static int srp_verifier_is_authenticated( struct SRPVerifier * ver ) +{ + return ver->authenticated; +} + + +static const char * srp_verifier_get_username( struct SRPVerifier * ver ) +{ + return ver->username; +} + + +/* Key length is SHA256_DIGEST_LENGTH */ +static const unsigned char * +srp_verifier_get_session_key( struct SRPVerifier * ver ) +{ + return ver->session_key; +} + + +/* user_M must be exactly SHA256_DIGEST_LENGTH bytes in size */ +static void srp_verifier_verify_session( struct SRPVerifier * ver, + const unsigned char * user_M, + const unsigned char ** bytes_HAMK ) +{ + if ( memcmp( ver->M, user_M, SHA256_DIGEST_LENGTH ) == 0 ) + { + ver->authenticated = 1; + *bytes_HAMK = ver->H_AMK; + } + else + *bytes_HAMK = NULL; +} + + +/*******************************************************************************/ + +static struct SRPUser * srp_user_new( const char * username, + const unsigned char * bytes_password, + int len_password ) +{ + struct SRPUser *usr; + int ulen = strlen(username) + 1; + + usr = (struct SRPUser *) malloc( sizeof(struct SRPUser) ); + + usr->a = BN_new(); + usr->A = BN_new(); + usr->S = BN_new(); + + usr->username = (const char *) malloc(ulen); + usr->password = (const unsigned char *) malloc(len_password); + usr->password_len = len_password; + + memcpy((char *)usr->username, username, ulen); + memcpy((char *)usr->password, bytes_password, len_password); + + usr->bytes_A = 0; + + return usr; +} + + +static void srp_user_delete( struct SRPUser * usr ) +{ + BN_free( usr->a ); + BN_free( usr->A ); + BN_free( usr->S ); + + free((char *)usr->username); + free((char *)usr->password); + + if (usr->bytes_A) + free( (char *)usr->bytes_A ); + + free( usr ); +} + + +static int srp_user_is_authenticated( struct SRPUser * usr) +{ + return usr->authenticated; +} + + +static const char * srp_user_get_username( struct SRPUser * usr ) +{ + return usr->username; +} + + +/* Key length is SHA256_DIGEST_LENGTH */ +static const unsigned char * srp_user_get_session_key( struct SRPUser * usr ) +{ + return usr->session_key; +} + + +/* Output: username, bytes_A, len_A */ +static void srp_user_start_authentication( struct SRPUser * usr, + const char ** username, + const unsigned char ** bytes_A, + int * len_A ) +{ + BN_CTX *ctx = BN_CTX_new(); + + BN_rand(usr->a, 256, -1, 0); + + BN_mod_exp(usr->A, g, usr->a, N, ctx); + + BN_CTX_free(ctx); + + *len_A = BN_num_bytes(usr->A); + *bytes_A = malloc( *len_A ); + + BN_bn2bin( usr->A, (unsigned char *) *bytes_A ); + + usr->bytes_A = *bytes_A; + *username = usr->username; +} + + +/* Output: bytes_M. Buffer length is SHA256_DIGEST_LENGTH */ +static void srp_user_process_challenge( struct SRPUser * usr, + const unsigned char * bytes_s, + int len_s, + const unsigned char * bytes_B, + int len_B, + const unsigned char ** bytes_M ) +{ + BIGNUM *s = BN_bin2bn(bytes_s, len_s, NULL); + BIGNUM *B = BN_bin2bn(bytes_B, len_B, NULL); + BIGNUM *u = 0; + BIGNUM *x = 0; + BIGNUM *v = BN_new(); + BIGNUM *tmp1 = BN_new(); + BIGNUM *tmp2 = BN_new(); + BIGNUM *tmp3 = BN_new(); + BN_CTX *ctx = BN_CTX_new(); + + u = H_nn(usr->A,B); + + x = calculate_x( s, usr->username, usr->password, usr->password_len ); + + /* SRP-6a safety check */ + if ( !BN_is_zero(B) && !BN_is_zero(u) ) + { + BN_mod_exp(v, g, x, N, ctx); + + /* S = (B - k*(g^x)) ^ (a + ux) */ + BN_mul(tmp1, u, x, ctx); + BN_add(tmp2, usr->a, tmp1); /* tmp2 = (a + ux) */ + BN_mod_exp(tmp1, g, x, N, ctx); + BN_mul(tmp3, k, tmp1, ctx); /* tmp3 = k*(g^x) */ + BN_sub(tmp1, B, tmp3); /* tmp1 = (B - K*(g^x)) */ + BN_mod_exp(usr->S, tmp1, tmp2, N, ctx); + + hash_num(usr->S, usr->session_key); + + calculate_M( usr->M, usr->username, s, usr->A, B, usr->session_key ); + calculate_H_AMK( usr->H_AMK, usr->A, usr->M, usr->session_key ); + + *bytes_M = usr->M; + } + else + { + *bytes_M = NULL; + } + + BN_free(s); + BN_free(B); + BN_free(u); + BN_free(x); + BN_free(v); + BN_free(tmp1); + BN_free(tmp2); + BN_free(tmp3); + BN_CTX_free(ctx); +} + +/* bytes_HAMK must be exactly SHA256_DIGEST_LENGTH bytes in size */ +static void srp_user_verify_session( struct SRPUser * usr, + const unsigned char * bytes_HAMK ) +{ + if ( memcmp( usr->H_AMK, bytes_HAMK, SHA256_DIGEST_LENGTH ) == 0 ) + usr->authenticated = 1; +} + + +/****************************************************************************** + * + * Python Module + * + *****************************************************************************/ + +typedef struct +{ + PyObject_HEAD + struct SRPVerifier * ver; + const unsigned char * bytes_B; + const unsigned char * bytes_s; + int len_B; + int len_s; +}PyVerifier; + + +typedef struct +{ + PyObject_HEAD + struct SRPUser * usr; +}PyUser; + + +static void ver_dealloc( PyVerifier * self ) +{ + if ( self->ver != NULL ) + srp_verifier_delete( self->ver ); + + if ( self->bytes_s != NULL ) + free( (char *)self->bytes_s ); + + self->ob_type->tp_free( (PyObject *) self ); +} + + +static void usr_dealloc( PyUser * self ) +{ + if ( self->usr != NULL ) + srp_user_delete( self->usr ); + self->ob_type->tp_free( (PyObject *) self ); +} + + +static PyObject * ver_new(PyTypeObject *type, PyObject *args, PyObject *kwds) +{ + PyVerifier *self = (PyVerifier *) type->tp_alloc(type, 0); + + if (!self) + return NULL; + + self->ver = NULL; + self->bytes_B = NULL; + self->bytes_s = NULL; + self->len_B = 0; + self->len_s = 0; + + return (PyObject *) self; +} + + +static PyObject * usr_new(PyTypeObject *type, PyObject *args, PyObject *kwds) +{ + PyUser *self = (PyUser *) type->tp_alloc(type, 0); + + if (!self) + return NULL; + + self->usr = NULL; + + return (PyObject *) self; +} + + +static int ver_init( PyVerifier *self, PyObject *args, PyObject *kwds ) +{ + const char *username; + const unsigned char *bytes_s, *bytes_v, *bytes_A; + int len_s, len_v, len_A; + + if ( self->ver != NULL ) + { + PyErr_SetString(PyExc_TypeError, "Type cannot be re-initialized"); + return -1; + } + + if ( ! PyArg_ParseTuple(args, "st#t#t#", &username, + &bytes_s, &len_s, + &bytes_v, &len_v, + &bytes_A, &len_A) ) + { + return -1; + } + + /* The srp_verifier_new command is computationally intensive... ~15ms on a + * 3Ghz x86 CPU. Allowing multiple, simultaneous calls here may speed + * things up for multi-cpu machines + */ + Py_BEGIN_ALLOW_THREADS + self->ver = srp_verifier_new( username, + bytes_s, len_s, + bytes_v, len_v, + bytes_A, len_A, + &self->bytes_B, &self->len_B ); + Py_END_ALLOW_THREADS + + if ( self->bytes_B == NULL ) + { + PyErr_SetString(PyExc_Exception, "SRP-6a safety check violated"); + return -1; + } + + self->bytes_s = malloc( len_s ); + self->len_s = len_s; + + memcpy( (char *)self->bytes_s, bytes_s, len_s ); + + return 0; +} + + +static int usr_init( PyUser *self, PyObject *args, PyObject *kwds ) +{ + const char *username; + const unsigned char *bytes_password; + int len_password; + + if ( self->usr != NULL ) + { + PyErr_SetString(PyExc_TypeError, "Type cannot be re-initialized"); + return -1; + } + + if ( ! PyArg_ParseTuple(args, "st#", &username, + &bytes_password, + &len_password) ) + { + return -1; + } + + + self->usr = srp_user_new( username, bytes_password, len_password ); + + return 0; +} + + +static PyObject * ver_is_authenticated( PyVerifier * self ) +{ + if ( self->ver == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + if ( srp_verifier_is_authenticated(self->ver) ) + Py_RETURN_TRUE; + else + Py_RETURN_FALSE; +} + + +static PyObject * usr_is_authenticated( PyUser * self ) +{ + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + if ( srp_user_is_authenticated(self->usr) ) + Py_RETURN_TRUE; + else + Py_RETURN_FALSE; +} + + +static PyObject * ver_get_username( PyVerifier * self ) +{ + if ( self->ver == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + return PyString_FromString( srp_verifier_get_username(self->ver) ); +} + + +static PyObject * usr_get_username( PyUser * self ) +{ + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + return PyString_FromString( srp_user_get_username(self->usr) ); +} + + +static PyObject * ver_get_session_key( PyVerifier * self ) +{ + if ( self->ver == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + if ( srp_verifier_is_authenticated(self->ver) ) + { + const char * u = (const char *)srp_verifier_get_session_key(self->ver); + return PyString_FromStringAndSize(u, SHA256_DIGEST_LENGTH); + } + else + Py_RETURN_NONE; +} + + +static PyObject * usr_get_session_key( PyUser * self ) +{ + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + if ( srp_user_is_authenticated(self->usr) ) + { + const char * u = (const char *) srp_user_get_session_key(self->usr); + return PyString_FromStringAndSize(u, SHA256_DIGEST_LENGTH); + } + else + Py_RETURN_NONE; +} + + +static PyObject * ver_get_challenge( PyVerifier * self ) +{ + if ( self->ver == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + if ( self->bytes_B == NULL ) { + PyErr_SetString(PyExc_Exception, "SRP-6a security check failed"); + return NULL; + } + + return Py_BuildValue("s#s#", self->bytes_s, + self->len_s, + self->bytes_B, + self->len_B); +} + + +static PyObject * ver_verify_session( PyVerifier * self, PyObject * args ) +{ + const unsigned char * bytes_M; + const unsigned char * bytes_HAMK; + int len_M; + + if ( self->ver == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + if ( ! PyArg_ParseTuple(args, "t#", &bytes_M, &len_M) ) + { + return NULL; + } + + if ( len_M != SHA256_DIGEST_LENGTH ) + Py_RETURN_NONE; + + srp_verifier_verify_session( self->ver, bytes_M, &bytes_HAMK ); + + if ( bytes_HAMK == NULL ) + Py_RETURN_NONE; + else + return PyString_FromStringAndSize((const char *) bytes_HAMK, + SHA256_DIGEST_LENGTH); +} + + +static PyObject * usr_start_authentication( PyUser * self ) +{ + const char * username; + const unsigned char * bytes_A; + int len_A; + + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + srp_user_start_authentication( self->usr, &username, &bytes_A, &len_A ); + + return Py_BuildValue("ss#", username, bytes_A, len_A); +} + + +static PyObject * usr_process_challenge( PyUser * self, PyObject * args ) +{ + const unsigned char * bytes_s, *bytes_B; + int len_s, len_B; + const unsigned char * bytes_M; + + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + if ( ! PyArg_ParseTuple(args, "t#t#", &bytes_s, &len_s, &bytes_B, + &len_B) ) + { + return NULL; + } + + /* The srp_user_process_challenge command is computationally intensive... + * ~20ms on a 2Ghz x86 CPU. Allowing multiple, simultaneous calls here will + * speed things up for multi-cpu machines. + */ + Py_BEGIN_ALLOW_THREADS + srp_user_process_challenge( self->usr, bytes_s, len_s, bytes_B, len_B, + &bytes_M ); + Py_END_ALLOW_THREADS + + if (bytes_M == NULL) + Py_RETURN_NONE; + else + return PyString_FromStringAndSize((const char *) bytes_M, + SHA256_DIGEST_LENGTH); +} + + +static PyObject * usr_verify_session( PyUser * self, PyObject * args ) +{ + const unsigned char * bytes_HAMK; + int len_HAMK; + + if ( self->usr == NULL ) { + PyErr_SetString(PyExc_Exception, "Type not initialized"); + return NULL; + } + + if ( ! PyArg_ParseTuple(args, "t#", &bytes_HAMK, &len_HAMK) ) + { + return NULL; + } + + if ( len_HAMK == SHA256_DIGEST_LENGTH ) + srp_user_verify_session( self->usr, bytes_HAMK ); + + Py_RETURN_NONE; +} + + +static PyObject * py_gen_sv( PyObject *self, PyObject *args ) +{ + const char *username; + const unsigned char *bytes_password, *bytes_s, *bytes_v; + int len_password, len_s, len_v; + PyObject *ret; + + if ( ! PyArg_ParseTuple(args, "st#", &username, &bytes_password, + &len_password) ) + return NULL; + + + srp_gen_sv( username, bytes_password, len_password, &bytes_s, &len_s, + &bytes_v, &len_v ); + + ret = Py_BuildValue("s#s#", bytes_s, len_s, bytes_v, len_v); + + free((char*)bytes_s); + free((char*)bytes_v); + + return ret; +} + + +/***********************************************************************************/ +static PyMethodDef PyVerifier_methods[] = { + {"authenticated", (PyCFunction) ver_is_authenticated, METH_NOARGS, + PyDoc_STR("Returns boolean indicating whether the session is " + "authenticated or not") + }, + {"get_username", (PyCFunction) ver_get_username, METH_NOARGS, + PyDoc_STR("Returns the username the Verifier instance is bound to.") + }, + {"get_session_key", (PyCFunction) ver_get_session_key, METH_NOARGS, + PyDoc_STR("Returns the session key for an authenticated session. " + "Returns None if the session is not authenticated.") + }, + {"get_challenge", (PyCFunction) ver_get_challenge, METH_NOARGS, + PyDoc_STR("Returns: (s,B) or None. The salt & challenge that " + "should be sent to the user or None if the SRP-6a " + "safety check fails.") + }, + {"verify_session", (PyCFunction) ver_verify_session, METH_VARARGS, + PyDoc_STR("Verifies the user based on their reply to " + "the challenge") + }, + {NULL} /* Sentinel */ +}; + + +static PyMethodDef PyUser_methods[] = { + {"authenticated", (PyCFunction) usr_is_authenticated, METH_NOARGS, + PyDoc_STR("Returns boolean indicating whether the session is " + "authenticated or not") + }, + {"get_username", (PyCFunction) usr_get_username, METH_NOARGS, + PyDoc_STR("Returns the username the User instance is bound to.") + }, + {"get_session_key", (PyCFunction) usr_get_session_key, METH_NOARGS, + PyDoc_STR("Returns the session key for an authenticated session. " + "Returns None if the session is not authenticated.") + }, + {"start_authentication", (PyCFunction) usr_start_authentication, + METH_NOARGS, + PyDoc_STR("Returns (username,A). The username and initial " + "authentication challenge to send to the verifier") + }, + {"process_challenge", (PyCFunction) usr_process_challenge, METH_VARARGS, + PyDoc_STR("Returns the reply to send to the server or None if the " + "SRP-6a safety check fails") + }, + {"verify_session", (PyCFunction) usr_verify_session, METH_VARARGS, + PyDoc_STR("Verifies the server based on its reply to the users " + "challenge response") + }, + {NULL} /* Sentinel */ +}; + + +static PyMethodDef srp_module_methods[] = { + {"gen_sv", (PyCFunction) py_gen_sv, METH_VARARGS, + PyDoc_STR("Returns (s,v): Generates a salt + verifier for the " + "given username and password") + }, + {NULL} /* Sentinel */ +}; + + +static PyTypeObject PyVerifier_Type = { + PyVarObject_HEAD_INIT(NULL, 0) + "_srp.Verifier", /*tp_name*/ + sizeof(PyVerifier), /*tp_basicsize*/ + 0, /*tp_itemsize*/ + /* methods */ + (destructor)ver_dealloc, /*tp_dealloc*/ + 0, /*tp_print*/ + 0, /*tp_getattr*/ + 0, /*tp_setattr*/ + 0, /*tp_compare*/ + 0, /*tp_repr*/ + 0, /*tp_as_number*/ + 0, /*tp_as_sequence*/ + 0, /*tp_as_mapping*/ + 0, /*tp_hash*/ + 0, /*tp_call*/ + 0, /*tp_str*/ + 0, /*tp_getattro*/ + 0, /*tp_setattro*/ + 0, /*tp_as_buffer*/ + Py_TPFLAGS_DEFAULT, /*tp_flags*/ + "SRP-6a verfier", /*tp_doc*/ + 0, /*tp_traverse*/ + 0, /*tp_clear*/ + 0, /*tp_richcompare*/ + 0, /*tp_weaklistoffset*/ + 0, /*tp_iter*/ + 0, /*tp_iternext*/ + PyVerifier_methods, /*tp_methods*/ + 0, /*tp_members*/ + 0, /*tp_getset*/ + 0, /*tp_base*/ + 0, /*tp_dict*/ + 0, /*tp_descr_get*/ + 0, /*tp_descr_set*/ + 0, /*tp_dictoffset*/ + (initproc)ver_init, /*tp_init*/ + 0, /*tp_alloc*/ + ver_new, /*tp_new*/ + 0, /*tp_free*/ + 0, /*tp_is_gc*/ +}; + + +static PyTypeObject PyUser_Type = { + PyVarObject_HEAD_INIT(NULL, 0) + "_srp.User", /*tp_name*/ + sizeof(PyUser), /*tp_basicsize*/ + 0, /*tp_itemsize*/ + /* methods */ + (destructor)usr_dealloc, /*tp_dealloc*/ + 0, /*tp_print*/ + 0, /*tp_getattr*/ + 0, /*tp_setattr*/ + 0, /*tp_compare*/ + 0, /*tp_repr*/ + 0, /*tp_as_number*/ + 0, /*tp_as_sequence*/ + 0, /*tp_as_mapping*/ + 0, /*tp_hash*/ + 0, /*tp_call*/ + 0, /*tp_str*/ + 0, /*tp_getattro*/ + 0, /*tp_setattro*/ + 0, /*tp_as_buffer*/ + Py_TPFLAGS_DEFAULT, /*tp_flags*/ + "SRP-6a User", /*tp_doc*/ + 0, /*tp_traverse*/ + 0, /*tp_clear*/ + 0, /*tp_richcompare*/ + 0, /*tp_weaklistoffset*/ + 0, /*tp_iter*/ + 0, /*tp_iternext*/ + PyUser_methods, /*tp_methods*/ + 0, /*tp_members*/ + 0, /*tp_getset*/ + 0, /*tp_base*/ + 0, /*tp_dict*/ + 0, /*tp_descr_get*/ + 0, /*tp_descr_set*/ + 0, /*tp_dictoffset*/ + (initproc)usr_init, /*tp_init*/ + 0, /*tp_alloc*/ + usr_new, /*tp_new*/ + 0, /*tp_free*/ + 0, /*tp_is_gc*/ +}; + + +PyMODINIT_FUNC +init_srp(void) +{ + int init_ok = 0; + PyObject *m = NULL; + PyObject *os = NULL; + PyObject *py_urandom = NULL; + + os = PyImport_ImportModule("os"); + + if (os == NULL) + return; + + py_urandom = PyObject_GetAttrString(os, "urandom"); + + if ( py_urandom && PyCallable_Check(py_urandom) ) + { + PyObject *args = Py_BuildValue("(i)", 32); + if ( args ) + { + PyObject *randstr = PyObject_CallObject(py_urandom, args); + if ( randstr && PyString_Check(randstr)) + { + char *buff = NULL; + Py_ssize_t slen = 0; + if (!PyString_AsStringAndSize(randstr, &buff, &slen)) + { + srp_init( buff, slen ); + init_ok = 1; + } + } + Py_XDECREF(randstr); + } + Py_XDECREF(args); + } + + Py_XDECREF(os); + Py_XDECREF(py_urandom); + + if (!init_ok) + { + PyErr_SetString(PyExc_ImportError, "Initialization failed"); + return; + } + + if ( Py_AtExit( &srp_fini ) ) + { + PyErr_SetString(PyExc_ImportError, "Failed to register atexit handler"); + return; + } + + + if (PyType_Ready(&PyVerifier_Type) < 0 || PyType_Ready(&PyUser_Type)) + return; + + m = Py_InitModule3("_srp", srp_module_methods,"SRP-6a implementation"); + + if (m == NULL) + return; + + Py_INCREF(&PyVerifier_Type); + Py_INCREF(&PyUser_Type); + + PyModule_AddObject(m, "Verifier", (PyObject*) &PyVerifier_Type ); + PyModule_AddObject(m, "User", (PyObject*) &PyUser_Type ); +}
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