/* * Secure Remote Password 6a implementation * Copyright (c) 2010 Tom Cocagne. All rights reserved. * https://github.com/cocagne/csrp * * The MIT License (MIT) * * Copyright (c) 2013 Tom Cocagne, 2015 est31 * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies * of the Software, and to permit persons to whom the Software is furnished to do * so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * */ #ifdef WIN32 #include #else #include #endif #include #include #include #include #include #include "srp.h" static int g_initialized = 0; #define RAND_BUFF_MAX 128 static unsigned int g_rand_idx; static unsigned char g_rand_buff[RAND_BUFF_MAX]; typedef struct { mpz_t N; mpz_t g; } NGConstant; struct NGHex { const char * n_hex; const char * g_hex; }; /* All constants here were pulled from Appendix A of RFC 5054 */ static struct NGHex global_Ng_constants[] = { { /* 1024 */ "EEAF0AB9ADB38DD69C33F80AFA8FC5E86072618775FF3C0B9EA2314C9C256576D674DF7496" "EA81D3383B4813D692C6E0E0D5D8E250B98BE48E495C1D6089DAD15DC7D7B46154D6B6CE8E" "F4AD69B15D4982559B297BCF1885C529F566660E57EC68EDBC3C05726CC02FD4CBF4976EAA" "9AFD5138FE8376435B9FC61D2FC0EB06E3", "2" }, { /* 2048 */ "AC6BDB41324A9A9BF166DE5E1389582FAF72B6651987EE07FC3192943DB56050A37329CBB4" "A099ED8193E0757767A13DD52312AB4B03310DCD7F48A9DA04FD50E8083969EDB767B0CF60" "95179A163AB3661A05FBD5FAAAE82918A9962F0B93B855F97993EC975EEAA80D740ADBF4FF" "747359D041D5C33EA71D281E446B14773BCA97B43A23FB801676BD207A436C6481F1D2B907" "8717461A5B9D32E688F87748544523B524B0D57D5EA77A2775D2ECFA032CFBDBF52FB37861" "60279004E57AE6AF874E7303CE53299CCC041C7BC308D82A5698F3A8D0C38271AE35F8E9DB" "FBB694B5C803D89F7AE435DE236D525F54759B65E372FCD68EF20FA7111F9E4AFF73", "2" }, {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}, {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}, {0,0} /* null sentinel */ }; static NGConstant * new_ng( SRP_NGType ng_type, const char * n_hex, const char * g_hex ) { NGConstant * ng = (NGConstant *) malloc( sizeof(NGConstant) ); mpz_init(ng->N); mpz_init(ng->g); if( !ng || !ng->N || !ng->g ) return 0; if ( ng_type != SRP_NG_CUSTOM ) { n_hex = global_Ng_constants[ ng_type ].n_hex; g_hex = global_Ng_constants[ ng_type ].g_hex; } mpz_set_str( ng->N, n_hex, 16 ); mpz_set_str( ng->g, g_hex, 16 ); return ng; } static void delete_ng( NGConstant * ng ) { if (ng) { mpz_clear( ng->N ); mpz_clear( ng->g ); free(ng); } } typedef union { SHA_CTX sha; SHA256_CTX sha256; //SHA512_CTX sha512; } HashCTX; struct SRPVerifier { SRP_HashAlgorithm hash_alg; NGConstant *ng; const char * username; const unsigned char * bytes_B; int authenticated; unsigned char M [SHA512_DIGEST_LENGTH]; unsigned char H_AMK [SHA512_DIGEST_LENGTH]; unsigned char session_key [SHA512_DIGEST_LENGTH]; }; struct SRPUser { SRP_HashAlgorithm hash_alg; NGConstant *ng; mpz_t a; mpz_t A; mpz_t S; const unsigned char * bytes_A; int authenticated; const char * username; const char * username_verifier; const unsigned char * password; int password_len; unsigned char M [SHA512_DIGEST_LENGTH]; unsigned char H_AMK [SHA512_DIGEST_LENGTH]; unsigned char session_key [SHA512_DIGEST_LENGTH]; }; static int hash_init( SRP_HashAlgorithm alg, HashCTX *c ) { switch (alg) { /*case SRP_SHA1 : return SHA1_Init( &c->sha ); case SRP_SHA224: return SHA224_Init( &c->sha256 );*/ case SRP_SHA256: return SHA256_Init( &c->sha256 ); /*case SRP_SHA384: return SHA384_Init( &c->sha512 ); case SRP_SHA512: return SHA512_Init( &c->sha512 );*/ default: return -1; }; } static int hash_update( SRP_HashAlgorithm alg, HashCTX *c, const void *data, size_t len ) { switch (alg) { /*case SRP_SHA1 : return SHA1_Update( &c->sha, data, len ); case SRP_SHA224: return SHA224_Update( &c->sha256, data, len );*/ case SRP_SHA256: return SHA256_Update( &c->sha256, data, len ); /*case SRP_SHA384: return SHA384_Update( &c->sha512, data, len ); case SRP_SHA512: return SHA512_Update( &c->sha512, data, len );*/ default: return -1; }; } static int hash_final( SRP_HashAlgorithm alg, HashCTX *c, unsigned char *md ) { switch (alg) { /*case SRP_SHA1 : return SHA1_Final( md, &c->sha ); case SRP_SHA224: return SHA224_Final( md, &c->sha256 );*/ case SRP_SHA256: return SHA256_Final( md, &c->sha256 ); /*case SRP_SHA384: return SHA384_Final( md, &c->sha512 ); case SRP_SHA512: return SHA512_Final( md, &c->sha512 );*/ default: return -1; }; } static unsigned char * hash( SRP_HashAlgorithm alg, const unsigned char *d, size_t n, unsigned char *md ) { switch (alg) { /*case SRP_SHA1 : return SHA1( d, n, md ); case SRP_SHA224: return SHA224( d, n, md );*/ case SRP_SHA256: return SHA256( d, n, md ); /*case SRP_SHA384: return SHA384( d, n, md ); case SRP_SHA512: return SHA512( d, n, md );*/ default: return 0; }; } static int hash_length( SRP_HashAlgorithm alg ) { switch (alg) { /*case SRP_SHA1 : return SHA_DIGEST_LENGTH; case SRP_SHA224: return SHA224_DIGEST_LENGTH;*/ case SRP_SHA256: return SHA256_DIGEST_LENGTH; /*case SRP_SHA384: return SHA384_DIGEST_LENGTH; case SRP_SHA512: return SHA512_DIGEST_LENGTH;*/ default: return -1; }; } inline int mpz_num_bytes( const mpz_t op ) { return (mpz_sizeinbase (op, 2) + 7) / 8; } inline void mpz_to_bin( const mpz_t op, unsigned char * to ) { mpz_export(to, NULL, 1, 1, 1, 0, op); } inline void mpz_from_bin( const unsigned char * s, int len, mpz_t ret ) { mpz_import(ret, len, 1, 1, 1, 0, s); } static int H_nn( mpz_t result, SRP_HashAlgorithm alg, const mpz_t n1, const mpz_t n2 ) { unsigned char buff[ SHA512_DIGEST_LENGTH ]; int len_n1 = mpz_num_bytes(n1); int len_n2 = mpz_num_bytes(n2); int nbytes = len_n1 + len_n2; unsigned char * bin = (unsigned char *) malloc( nbytes ); if (!bin) { return 0; } mpz_to_bin(n1, bin); mpz_to_bin(n2, bin + len_n1); hash( alg, bin, nbytes, buff ); free(bin); mpz_from_bin(buff, hash_length(alg), result); return 1; } static int H_ns( mpz_t result, SRP_HashAlgorithm alg, const unsigned char * n, int len_n, const unsigned char * bytes, int len_bytes ) { unsigned char buff[ SHA512_DIGEST_LENGTH ]; int nbytes = len_n + len_bytes; unsigned char * bin = (unsigned char *) malloc( nbytes ); if (!bin) return 0; memcpy( bin, n, len_n ); memcpy( bin + len_n, bytes, len_bytes ); hash( alg, bin, nbytes, buff ); free(bin); mpz_from_bin(buff, hash_length(alg), result); return 1; } static int calculate_x( mpz_t result, SRP_HashAlgorithm alg, const unsigned char * salt, int salt_len, const char * username, const unsigned char * password, int password_len ) { unsigned char ucp_hash[SHA512_DIGEST_LENGTH]; HashCTX ctx; hash_init( alg, &ctx ); hash_update( alg, &ctx, username, strlen(username) ); hash_update( alg, &ctx, ":", 1 ); hash_update( alg, &ctx, password, password_len ); hash_final( alg, &ctx, ucp_hash ); return H_ns( result, alg, salt, salt_len, ucp_hash, hash_length(alg) ); } static void update_hash_n( SRP_HashAlgorithm alg, HashCTX *ctx, const mpz_t n ) { unsigned long len = mpz_num_bytes(n); unsigned char * n_bytes = (unsigned char *) malloc( len ); if (!n_bytes) return; mpz_to_bin(n, n_bytes); hash_update(alg, ctx, n_bytes, len); free(n_bytes); } static void hash_num( SRP_HashAlgorithm alg, const mpz_t n, unsigned char * dest ) { int nbytes = mpz_num_bytes(n); unsigned char * bin = (unsigned char *) malloc( nbytes ); if(!bin) return; mpz_to_bin(n, bin); hash( alg, bin, nbytes, dest ); free(bin); } static void calculate_M( SRP_HashAlgorithm alg, NGConstant *ng, unsigned char * dest, const char * I, const unsigned char * s_bytes, int s_len, const mpz_t A, const mpz_t B, const unsigned char * K ) { unsigned char H_N[ SHA512_DIGEST_LENGTH ]; unsigned char H_g[ SHA512_DIGEST_LENGTH ]; unsigned char H_I[ SHA512_DIGEST_LENGTH ]; unsigned char H_xor[ SHA512_DIGEST_LENGTH ]; HashCTX ctx; int i = 0; int hash_len = hash_length(alg); hash_num( alg, ng->N, H_N ); hash_num( alg, ng->g, H_g ); hash(alg, (const unsigned char *)I, strlen(I), H_I); for (i=0; i < hash_len; i++ ) H_xor[i] = H_N[i] ^ H_g[i]; hash_init( alg, &ctx ); hash_update( alg, &ctx, H_xor, hash_len ); hash_update( alg, &ctx, H_I, hash_len ); hash_update( alg, &ctx, s_bytes, s_len ); update_hash_n( alg, &ctx, A ); update_hash_n( alg, &ctx, B ); hash_update( alg, &ctx, K, hash_len ); hash_final( alg, &ctx, dest ); } static void calculate_H_AMK( SRP_HashAlgorithm alg, unsigned char *dest, const mpz_t A, const unsigned char * M, const unsigned char * K ) { HashCTX ctx; hash_init( alg, &ctx ); update_hash_n( alg, &ctx, A ); hash_update( alg, &ctx, M, hash_length(alg) ); hash_update( alg, &ctx, K, hash_length(alg) ); hash_final( alg, &ctx, dest ); } static int fill_buff() { g_rand_idx = 0; #ifdef WIN32 HCRYPTPROV wctx; #else FILE *fp = 0; #endif #ifdef WIN32 CryptAcquireContext(&wctx, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT); CryptGenRandom(wctx, sizeof(g_rand_buff), (BYTE*) g_rand_buff); CryptReleaseContext(wctx, 0); return 1; #else fp = fopen("/dev/urandom", "r"); if (fp) { fread(g_rand_buff, sizeof(g_rand_buff), 1, fp); fclose(fp); return 1; } #endif return 0; } static void mpz_fill_random( mpz_t num ) { // was call: BN_rand(num, 256, -1, 0); if (RAND_BUFF_MAX - g_rand_idx < 32) fill_buff(); mpz_from_bin( (char *) (&g_rand_buff[g_rand_idx]), 32, num ); g_rand_idx += 32; } static void init_random() { if (g_initialized) return; g_initialized = fill_buff(); } /*********************************************************************************************************** * * Exported Functions * ***********************************************************************************************************/ void srp_create_salted_verification_key( SRP_HashAlgorithm alg, SRP_NGType ng_type, const char * username_for_verifier, const unsigned char * password, int len_password, const unsigned char ** bytes_s, int * len_s, const unsigned char ** bytes_v, int * len_v, const char * n_hex, const char * g_hex ) { mpz_t v; mpz_init(v); mpz_t x; mpz_init(x); NGConstant * ng = new_ng( ng_type, n_hex, g_hex ); if( !v || !ng ) goto cleanup_and_exit; if( bytes_s == NULL ) { *len_s = 16; if ( RAND_BUFF_MAX - g_rand_idx < 16 ) fill_buff(); *bytes_s = (const unsigned char *) malloc( sizeof(char) * 16 ); memcpy( (unsigned char *) *bytes_s, &g_rand_buff + g_rand_idx, sizeof(char) * 16 ); g_rand_idx += 16; } if( !calculate_x( x, alg, *bytes_s, *len_s, username_for_verifier, password, len_password )) goto cleanup_and_exit; mpz_powm(v, ng->g, x, ng->N); *len_v = mpz_num_bytes(v); *bytes_v = (const unsigned char *) malloc( *len_v ); if (!bytes_v) goto cleanup_and_exit; mpz_to_bin(v, (unsigned char *) *bytes_v); cleanup_and_exit: delete_ng( ng ); mpz_clear(v); mpz_clear(x); } /* Out: bytes_B, len_B. * * On failure, bytes_B will be set to NULL and len_B will be set to 0 */ struct SRPVerifier * srp_verifier_new( SRP_HashAlgorithm alg, SRP_NGType ng_type, 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, const char * n_hex, const char * g_hex ) { mpz_t v; mpz_init(v); mpz_from_bin(bytes_v, len_v, v); mpz_t A; mpz_init(A); mpz_from_bin(bytes_A, len_A, A); mpz_t u; mpz_init(u); mpz_t B; mpz_init(B); mpz_t S; mpz_init(S); mpz_t b; mpz_init(b); mpz_t k; mpz_init(k); mpz_t tmp1; mpz_init(tmp1); mpz_t tmp2; mpz_init(tmp2); int ulen = strlen(username) + 1; NGConstant *ng = new_ng( ng_type, n_hex, g_hex ); struct SRPVerifier *ver = 0; *len_B = 0; *bytes_B = 0; if( !v || !A || !B || !S || !b || !tmp1 || !tmp2 || !ng ) goto cleanup_and_exit; ver = (struct SRPVerifier *) malloc( sizeof(struct SRPVerifier) ); if (!ver) goto cleanup_and_exit; init_random(); /* Only happens once */ ver->username = (char *) malloc( ulen ); ver->hash_alg = alg; ver->ng = ng; if (!ver->username) { free(ver); ver = 0; goto cleanup_and_exit; } memcpy( (char*)ver->username, username, ulen ); ver->authenticated = 0; /* SRP-6a safety check */ mpz_mod(tmp1, A, ng->N); if ( mpz_sgn(tmp1) != 0 ) { mpz_fill_random(b); H_nn(k, alg, ng->N, ng->g); /* B = kv + g^b */ mpz_mul(tmp1, k, v); mpz_powm(tmp2, ng->g, b, ng->N); mpz_add(B, tmp1, tmp2); H_nn(u, alg, A, B); /* S = (A *(v^u)) ^ b */ mpz_powm(tmp1, v, u, ng->N); mpz_mul(tmp2, A, tmp1); mpz_powm(S, tmp2, b, ng->N); hash_num(alg, S, ver->session_key); calculate_M( alg, ng, ver->M, username, bytes_s, len_s, A, B, ver->session_key ); calculate_H_AMK( alg, ver->H_AMK, A, ver->M, ver->session_key ); *len_B = mpz_num_bytes(B); *bytes_B = malloc( *len_B ); if( !*bytes_B ) { free( (void*) ver->username ); free( ver ); ver = 0; *len_B = 0; goto cleanup_and_exit; } mpz_to_bin( B, (unsigned char *) *bytes_B ); ver->bytes_B = *bytes_B; } cleanup_and_exit: mpz_clear(v); mpz_clear(A); if (u) mpz_clear(u); if (k) mpz_clear(k); mpz_clear(B); mpz_clear(S); mpz_clear(b); mpz_clear(tmp1); mpz_clear(tmp2); return ver; } void srp_verifier_delete( struct SRPVerifier * ver ) { if (ver) { delete_ng( ver->ng ); free( (char *) ver->username ); free( (unsigned char *) ver->bytes_B ); memset(ver, 0, sizeof(*ver)); free( ver ); } } int srp_verifier_is_authenticated( struct SRPVerifier * ver ) { return ver->authenticated; } const char * srp_verifier_get_username( struct SRPVerifier * ver ) { return ver->username; } const unsigned char * srp_verifier_get_session_key( struct SRPVerifier * ver, int * key_length ) { if (key_length) *key_length = hash_length( ver->hash_alg ); return ver->session_key; } int srp_verifier_get_session_key_length( struct SRPVerifier * ver ) { return hash_length( ver->hash_alg ); } /* user_M must be exactly SHA512_DIGEST_LENGTH bytes in size */ void srp_verifier_verify_session( struct SRPVerifier * ver, const unsigned char * user_M, const unsigned char ** bytes_HAMK ) { if ( memcmp( ver->M, user_M, hash_length(ver->hash_alg) ) == 0 ) { ver->authenticated = 1; *bytes_HAMK = ver->H_AMK; } else *bytes_HAMK = NULL; } /*******************************************************************************/ struct SRPUser * srp_user_new( SRP_HashAlgorithm alg, SRP_NGType ng_type, const char * username, const char * username_for_verifier, const unsigned char * bytes_password, int len_password, const char * n_hex, const char * g_hex ) { struct SRPUser *usr = (struct SRPUser *) malloc( sizeof(struct SRPUser) ); int ulen = strlen(username) + 1; int uvlen = strlen(username_for_verifier) + 1; if (!usr) goto err_exit; init_random(); /* Only happens once */ usr->hash_alg = alg; usr->ng = new_ng( ng_type, n_hex, g_hex ); mpz_init(usr->a); mpz_init(usr->A); mpz_init(usr->S); if (!usr->ng || !usr->a || !usr->A || !usr->S) goto err_exit; usr->username = (const char *) malloc(ulen); usr->username_verifier = (const char *) malloc(uvlen); usr->password = (const unsigned char *) malloc(len_password); usr->password_len = len_password; if (!usr->username || !usr->password) goto err_exit; memcpy((char *)usr->username, username, ulen); memcpy((char *)usr->username_verifier, username_for_verifier, uvlen); memcpy((char *)usr->password, bytes_password, len_password); usr->authenticated = 0; usr->bytes_A = 0; return usr; err_exit: if (usr) { mpz_clear(usr->a); mpz_clear(usr->A); mpz_clear(usr->S); if (usr->username) free((void*)usr->username); if (usr->password) { memset((void*)usr->password, 0, usr->password_len); free((void*)usr->password); } free(usr); } return 0; } void srp_user_delete( struct SRPUser * usr ) { if( usr ) { mpz_clear( usr->a ); mpz_clear( usr->A ); mpz_clear( usr->S ); delete_ng( usr->ng ); memset((void*)usr->password, 0, usr->password_len); free((char *)usr->username); free((char *)usr->password); if (usr->bytes_A) free( (char *)usr->bytes_A ); memset(usr, 0, sizeof(*usr)); free( usr ); } } int srp_user_is_authenticated( struct SRPUser * usr) { return usr->authenticated; } const char * srp_user_get_username( struct SRPUser * usr ) { return usr->username; } const unsigned char * srp_user_get_session_key( struct SRPUser * usr, int * key_length ) { if (key_length) *key_length = hash_length( usr->hash_alg ); return usr->session_key; } int srp_user_get_session_key_length( struct SRPUser * usr ) { return hash_length( usr->hash_alg ); } /* Output: username, bytes_A, len_A */ void srp_user_start_authentication( struct SRPUser * usr, const char ** username, const unsigned char ** bytes_A, int * len_A ) { mpz_fill_random(usr->a); mpz_powm(usr->A, usr->ng->g, usr->a, usr->ng->N); *len_A = mpz_num_bytes(usr->A); *bytes_A = malloc( *len_A ); if (!*bytes_A) { *len_A = 0; *bytes_A = 0; *username = 0; return; } mpz_to_bin( usr->A, (unsigned char *) *bytes_A ); usr->bytes_A = *bytes_A; *username = usr->username; } /* Output: bytes_M. Buffer length is SHA512_DIGEST_LENGTH */ 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, int * len_M ) { mpz_t B; mpz_init(B); mpz_from_bin(bytes_B, len_B, B); mpz_t u; mpz_init(u); mpz_t x; mpz_init(x); mpz_t k; mpz_init(k); mpz_t v; mpz_init(v); mpz_t tmp1; mpz_init(tmp1); mpz_t tmp2; mpz_init(tmp2); mpz_t tmp3; mpz_init(tmp3); *len_M = 0; *bytes_M = 0; if( !B || !u || !x || !k || !v || !tmp1 || !tmp2 || !tmp3 ) goto cleanup_and_exit; if (!H_nn(u, usr->hash_alg, usr->A, B)) goto cleanup_and_exit; calculate_x( x, usr->hash_alg, bytes_s, len_s, usr->username_verifier, usr->password, usr->password_len ); if (!x) goto cleanup_and_exit; H_nn(k, usr->hash_alg, usr->ng->N, usr->ng->g); if (!k) goto cleanup_and_exit; /* SRP-6a safety check */ if ( mpz_sgn(B) != 0 && mpz_sgn(u) != 0 ) { mpz_powm(v, usr->ng->g, x, usr->ng->N); /* S = (B - k*(g^x)) ^ (a + ux) */ mpz_mul(tmp1, u, x); mpz_add(tmp2, usr->a, tmp1); /* tmp2 = (a + ux) */ mpz_powm(tmp1, usr->ng->g, x, usr->ng->N); mpz_mul(tmp3, k, tmp1); /* tmp3 = k*(g^x) */ mpz_sub(tmp1, B, tmp3); /* tmp1 = (B - K*(g^x)) */ mpz_powm(usr->S, tmp1, tmp2, usr->ng->N); hash_num(usr->hash_alg, usr->S, usr->session_key); calculate_M( usr->hash_alg, usr->ng, usr->M, usr->username, bytes_s, len_s, usr->A, B, usr->session_key ); calculate_H_AMK( usr->hash_alg, usr->H_AMK, usr->A, usr->M, usr->session_key ); *bytes_M = usr->M; if (len_M) *len_M = hash_length( usr->hash_alg ); } else { *bytes_M = NULL; if (len_M) *len_M = 0; } cleanup_and_exit: mpz_clear(B); mpz_clear(u); mpz_clear(x); mpz_clear(k); mpz_clear(v); mpz_clear(tmp1); mpz_clear(tmp2); mpz_clear(tmp3); } void srp_user_verify_session( struct SRPUser * usr, const unsigned char * bytes_HAMK ) { if ( memcmp( usr->H_AMK, bytes_HAMK, hash_length(usr->hash_alg) ) == 0 ) usr->authenticated = 1; }