/* * Secure Remote Password 6a implementation based on mbedtls. * * Copyright (c) 2017 Johannes Schriewer * https://github.com/dunkelstern/mbedtls-csrp * * Copyright (c) 2015 Dieter Wimberger * https://github.com/dwimberger/mbedtls-csrp * * Derived from: * Copyright (c) 2010 Tom Cocagne. All rights reserved. * https://github.com/cocagne/csrp * * The MIT License (MIT) * * Copyright (c) 2015 Tom Cocagne, Dieter Wimberger * * 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. * */ #include #include #include #include "mbedtls/bignum.h" #include "mbedtls/entropy.h" #include "mbedtls/ctr_drbg.h" #include "mbedtls/sha1.h" #include "mbedtls/sha256.h" #include "mbedtls/sha512.h" #include "mbedtls/version.h" #if MBEDTLS_VERSION_NUMBER > 0x02070000 #define USE_SHA_RET 1 #else #define USE_SHA_RET 0 #endif #if MBEDTLS_VERSION_NUMBER > 0x03000000 #include #endif #include "srp.h" static int g_initialized = 0; static mbedtls_entropy_context entropy_ctx; static mbedtls_ctr_drbg_context ctr_drbg_ctx; static mbedtls_mpi * RR; typedef struct { BIGNUM *N; BIGNUM *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[] = { { /* 512 */ "D66AAFE8E245F9AC245A199F62CE61AB8FA90A4D80C71CD2ADFD0B9DA163B29F2A34AFBDB3B" "1B5D0102559CE63D8B6E86B0AA59C14E79D4AA62D1748E4249DF3", "2" }, { /* 768 */ "B344C7C4F8C495031BB4E04FF8F84EE95008163940B9558276744D91F7CC9F402653BE7147F" "00F576B93754BCDDF71B636F2099E6FFF90E79575F3D0DE694AFF737D9BE9713CEF8D837ADA" "6380B1093E94B6A529A8C6C2BE33E0867C60C3262B", "2" }, { /* 1024 */ "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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}, {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) ); ng->N = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); ng->g = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(ng->N); mbedtls_mpi_init(ng->g); if( !ng || !ng->N || !ng->g ) { if (ng->N) mbedtls_mpi_free(ng->N); if (ng->g) mbedtls_mpi_free(ng->g); free(ng); 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; } mbedtls_mpi_read_string( ng->N, 16, n_hex); mbedtls_mpi_read_string( ng->g, 16, g_hex); return ng; } static void delete_ng( NGConstant * ng ) { if (ng) { mbedtls_mpi_free( ng->N ); mbedtls_mpi_free( ng->g ); free(ng->N); free(ng->g); free(ng); } } typedef union { mbedtls_sha1_context sha; mbedtls_sha256_context sha256; mbedtls_sha512_context sha512; } HashCTX; struct SRPSession { SRP_HashAlgorithm hash_alg; NGConstant *ng; }; 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; BIGNUM *a; BIGNUM *A; BIGNUM *S; const unsigned char * bytes_A; int authenticated; const char * username; const unsigned char * password; size_t password_len; unsigned char M [SHA512_DIGEST_LENGTH]; unsigned char H_AMK [SHA512_DIGEST_LENGTH]; unsigned char session_key [SHA512_DIGEST_LENGTH]; }; static void hash_init( SRP_HashAlgorithm alg, HashCTX *c ) { switch (alg) { case SRP_SHA1 : mbedtls_sha1_init( &c->sha ); break; case SRP_SHA256: mbedtls_sha256_init( &c->sha256 ); break; case SRP_SHA512: mbedtls_sha512_init( &c->sha512 ); break; default: return; }; } /* static void hash_start( SRP_HashAlgorithm alg, HashCTX *c ) { switch (alg) { case SRP_SHA1 : mbedtls_sha1_starts( &c->sha ); case SRP_SHA224: mbedtls_sha256_starts( &c->sha256, 1 ); case SRP_SHA256: mbedtls_sha256_starts( &c->sha256, 0 ); case SRP_SHA384: mbedtls_sha512_starts( &c->sha512, 1 ); case SRP_SHA512: mbedtls_sha512_starts( &c->sha512, 0 ); default: return; }; }*/ static int hash_update( SRP_HashAlgorithm alg, HashCTX *c, const void *data, size_t len ) { #if !USE_SHA_RET switch (alg) { case SRP_SHA1 : mbedtls_sha1_update( &c->sha, data, len ); break; case SRP_SHA224: mbedtls_sha256_update( &c->sha256, data, len ); break; case SRP_SHA256: mbedtls_sha256_update( &c->sha256, data, len ); break; case SRP_SHA384: mbedtls_sha512_update( &c->sha512, data, len ); break; case SRP_SHA512: mbedtls_sha512_update( &c->sha512, data, len ); break; default: return -1; }; return 0; #else switch (alg) { case SRP_SHA1: return mbedtls_sha1_update_ret( &c->sha, data, len ); case SRP_SHA224: return mbedtls_sha256_update_ret( &c->sha256, data, len ); case SRP_SHA256: return mbedtls_sha256_update_ret( &c->sha256, data, len ); case SRP_SHA384: return mbedtls_sha512_update_ret( &c->sha512, data, len ); case SRP_SHA512: return mbedtls_sha512_update_ret( &c->sha512, data, len ); default: return -1; }; #endif } static int hash_final( SRP_HashAlgorithm alg, HashCTX *c, unsigned char *md ) { #if !USE_SHA_RET switch (alg) { case SRP_SHA1 : mbedtls_sha1_finish( &c->sha, md ); break; case SRP_SHA224: mbedtls_sha256_finish( &c->sha256, md ); break; case SRP_SHA256: mbedtls_sha256_finish( &c->sha256, md ); break; case SRP_SHA384: mbedtls_sha512_finish( &c->sha512, md ); break; case SRP_SHA512: mbedtls_sha512_finish( &c->sha512, md ); break; default: return -1; }; return 0; #else switch (alg) { case SRP_SHA1 : return mbedtls_sha1_finish_ret( &c->sha, md ); case SRP_SHA224: return mbedtls_sha256_finish_ret( &c->sha256, md ); case SRP_SHA256: return mbedtls_sha256_finish_ret( &c->sha256, md ); case SRP_SHA384: return mbedtls_sha512_finish_ret( &c->sha512, md ); case SRP_SHA512: return mbedtls_sha512_finish_ret( &c->sha512, md ); default: return -1; }; #endif } static int hash( SRP_HashAlgorithm alg, const unsigned char *d, size_t n, unsigned char *md ) { #if !USE_SHA_RET switch (alg) { case SRP_SHA1 : mbedtls_sha1( d, n, md ); break; case SRP_SHA224: mbedtls_sha256( d, n, md, 1); break; case SRP_SHA256: mbedtls_sha256( d, n, md, 0); break; case SRP_SHA384: mbedtls_sha512( d, n, md, 1 ); break; case SRP_SHA512: mbedtls_sha512( d, n, md, 0 ); break; default: return -1; }; return 0; #else switch (alg) { case SRP_SHA1 : return mbedtls_sha1_ret( d, n, md ); case SRP_SHA224: return mbedtls_sha256_ret( d, n, md, 1); case SRP_SHA256: return mbedtls_sha256_ret( d, n, md, 0); case SRP_SHA384: return mbedtls_sha512_ret( d, n, md, 1 ); case SRP_SHA512: return mbedtls_sha512_ret( d, n, md, 0 ); default: return -1; }; #endif } static int hash_length( SRP_HashAlgorithm alg ) { switch (alg) { case SRP_SHA1 : return SHA1_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; }; } static BIGNUM * H_nn( SRP_HashAlgorithm alg, const BIGNUM * n1, const BIGNUM * n2 ) { unsigned char buff[ SHA512_DIGEST_LENGTH ]; size_t len_n1 = mbedtls_mpi_size(n1); size_t len_n2 = mbedtls_mpi_size(n2); size_t nbytes = len_n1 + len_n2; unsigned char * bin = (unsigned char *) malloc( nbytes ); if (!bin) return 0; mbedtls_mpi_write_binary( n1, bin, len_n1 ); mbedtls_mpi_write_binary( n2, bin+len_n1, len_n2 ); hash( alg, bin, nbytes, buff ); free(bin); BIGNUM * bn; bn = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(bn); mbedtls_mpi_read_binary( bn, buff, hash_length(alg) ); return bn; } static BIGNUM * H_ns( SRP_HashAlgorithm alg, const BIGNUM * n, const unsigned char * bytes, size_t len_bytes ) { unsigned char buff[ SHA512_DIGEST_LENGTH ]; size_t len_n = mbedtls_mpi_size(n); size_t nbytes = len_n + len_bytes; unsigned char * bin = (unsigned char *) malloc( nbytes ); if (!bin) return 0; mbedtls_mpi_write_binary( n, bin, len_n ); memcpy( bin + len_n, bytes, len_bytes ); hash( alg, bin, nbytes, buff ); free(bin); BIGNUM * bn; bn = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(bn); mbedtls_mpi_read_binary( bn, buff, hash_length(alg) ); return bn; } static BIGNUM * calculate_x( SRP_HashAlgorithm alg, const BIGNUM * salt, const char * username, const unsigned char * password, size_t password_len ) { unsigned char ucp_hash[SHA512_DIGEST_LENGTH]; HashCTX ctx; hash_init( alg, &ctx ); if (hash_update( alg, &ctx, username, strlen(username) ) != 0) return NULL; if (hash_update( alg, &ctx, ":", 1 ) != 0) return NULL; if (hash_update( alg, &ctx, password, password_len ) != 0) return NULL; if (hash_final( alg, &ctx, ucp_hash ) != 0) return NULL; return H_ns( alg, salt, ucp_hash, hash_length(alg) ); } static void update_hash_n( SRP_HashAlgorithm alg, HashCTX *ctx, const BIGNUM * n ) { unsigned long len = mbedtls_mpi_size(n); unsigned char * n_bytes = (unsigned char *) malloc( len ); if (!n_bytes) return; mbedtls_mpi_write_binary( n, n_bytes, len ); hash_update(alg, ctx, n_bytes, len); free(n_bytes); } static void hash_num( SRP_HashAlgorithm alg, const BIGNUM * n, unsigned char * dest ) { size_t nbytes = mbedtls_mpi_size(n); unsigned char * bin = (unsigned char *) malloc( nbytes ); if(!bin) return; mbedtls_mpi_write_binary( n, bin, nbytes ); hash( alg, bin, nbytes, dest ); free(bin); } static void calculate_M( SRP_HashAlgorithm alg, NGConstant *ng, unsigned char * dest, const char * I, const BIGNUM * s, const BIGNUM * A, const BIGNUM * B, const unsigned char * K ) { unsigned char H_N[ SHA512_DIGEST_LENGTH ] = { '\0' }; unsigned char H_g[ SHA512_DIGEST_LENGTH ] = { '\0' }; unsigned char H_I[ SHA512_DIGEST_LENGTH ] = { '\0' }; unsigned char H_xor[ SHA512_DIGEST_LENGTH ] = { '\0' }; 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 ); update_hash_n( alg, &ctx, s ); 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 BIGNUM * 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 void init_random() { if (g_initialized) return; mbedtls_entropy_init( &entropy_ctx ); mbedtls_ctr_drbg_init( &ctr_drbg_ctx ); unsigned char hotBits[128] = { 82, 42, 71, 87, 124, 241, 30, 1, 54, 239, 240, 121, 89, 9, 151, 11, 60, 226, 142, 47, 115, 157, 100, 126, 242, 132, 46, 12, 56, 197, 194, 76, 198, 122, 90, 241, 255, 43, 120, 209, 69, 21, 195, 212, 100, 251, 18, 111, 30, 238, 24, 199, 238, 236, 138, 225, 45, 15, 42, 83, 114, 132, 165, 141, 32, 185, 167, 100, 131, 23, 236, 9, 11, 51, 130, 136, 97, 161, 36, 174, 129, 234, 2, 54, 119, 184, 70, 103, 118, 109, 122, 15, 24, 23, 166, 203, 102, 160, 77, 100, 17, 4, 132, 138, 215, 204, 109, 245, 122, 9, 184, 89, 70, 247, 125, 97, 213, 240, 85, 243, 91, 226, 127, 64, 136, 37, 154, 232 }; mbedtls_ctr_drbg_seed( &ctr_drbg_ctx, mbedtls_entropy_func, &entropy_ctx, hotBits, 128 ); RR = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(RR); g_initialized = 1; } /*********************************************************************************************************** * * Exported Functions * ***********************************************************************************************************/ struct SRPSession * srp_session_new( SRP_HashAlgorithm alg, SRP_NGType ng_type, const char * n_hex, const char * g_hex) { struct SRPSession * session; session = (struct SRPSession *)malloc(sizeof(struct SRPSession)); memset(session, 0, sizeof(struct SRPSession)); session->hash_alg = alg; session->ng = new_ng( ng_type, n_hex, g_hex ); return session; } void srp_session_delete(struct SRPSession *session) { delete_ng( session->ng ); free(session); } void srp_random_seed( const unsigned char * random_data, size_t data_length ) { g_initialized = 1; if( mbedtls_ctr_drbg_seed( &ctr_drbg_ctx, mbedtls_entropy_func, &entropy_ctx, (const unsigned char *) random_data, data_length ) != 0 ) { return; } } void srp_create_salted_verification_key( struct SRPSession *session, const char * username, const unsigned char * password, size_t len_password, const unsigned char ** bytes_s, size_t * len_s, const unsigned char ** bytes_v, size_t * len_v) { BIGNUM * s; BIGNUM * v; BIGNUM * x = 0; s = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(s); v = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(v); if( !session || !s || !v ) goto cleanup_and_exit; init_random(); /* Only happens once */ mbedtls_mpi_fill_random( s, 32, &mbedtls_ctr_drbg_random, &ctr_drbg_ctx ); x = calculate_x( session->hash_alg, s, username, password, len_password ); if( !x ) goto cleanup_and_exit; mbedtls_mpi_exp_mod(v, session->ng->g, x, session->ng->N, RR); *len_s = mbedtls_mpi_size(s); *len_v = mbedtls_mpi_size(v); *bytes_s = (const unsigned char *) malloc( *len_s ); *bytes_v = (const unsigned char *) malloc( *len_v ); if (!bytes_s || !bytes_v) goto cleanup_and_exit; mbedtls_mpi_write_binary( s, (unsigned char *)*bytes_s, *len_s ); mbedtls_mpi_write_binary( v, (unsigned char *)*bytes_v, *len_v ); cleanup_and_exit: mbedtls_mpi_free(s); free(s); mbedtls_mpi_free(v); free(v); mbedtls_mpi_free(x); free(x); //TODO: 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 */ struct SRPVerifier * srp_verifier_new( struct SRPSession *session, const char *username, const unsigned char * bytes_s, size_t len_s, const unsigned char * bytes_v, size_t len_v, const unsigned char * bytes_A, size_t len_A, const unsigned char ** bytes_B, size_t * len_B) { BIGNUM *s; s = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(s); mbedtls_mpi_read_binary(s, bytes_s, len_s); BIGNUM *v; v = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(v); mbedtls_mpi_read_binary(v, bytes_v, len_v); BIGNUM *A; A = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(A); mbedtls_mpi_read_binary(A, bytes_A, len_A); BIGNUM *u = 0; BIGNUM *B; B = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(B); BIGNUM *S; S = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(S); BIGNUM *b; b = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(b); BIGNUM *k = 0; BIGNUM *tmp1; tmp1 = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(tmp1); BIGNUM *tmp2; tmp2 = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(tmp2); size_t ulen = strlen(username) + 1; struct SRPVerifier *ver = 0; ver = (struct SRPVerifier *) malloc( sizeof(struct SRPVerifier) ); *len_B = 0; *bytes_B = 0; if( !session || !B || !S || !b || !tmp1 || !tmp2 || !ver ) { goto cleanup_and_exit; } init_random(); /* Only happens once */ ver->hash_alg = session->hash_alg; ver->ng = session->ng; ver->username = (char *) malloc( ulen ); // FIXME if (!ver->username) { free(ver); ver = 0; goto cleanup_and_exit; } memcpy( (char*)ver->username, username, ulen ); ver->authenticated = 0; /* SRP-6a safety check */ mbedtls_mpi_mod_mpi( tmp1, A, session->ng->N ); if ( mbedtls_mpi_cmp_int( tmp1, 0 ) != 0) { mbedtls_mpi_fill_random( b, 32, &mbedtls_ctr_drbg_random, &ctr_drbg_ctx ); k = H_nn(session->hash_alg, session->ng->N, session->ng->g); /* B = kv + g^b */ mbedtls_mpi_mul_mpi( tmp1, k, v); mbedtls_mpi_exp_mod( tmp2, session->ng->g, b, session->ng->N, RR ); mbedtls_mpi_add_mpi( tmp1, tmp1, tmp2 ); mbedtls_mpi_mod_mpi( B, tmp1, session->ng->N ); u = H_nn(session->hash_alg, A, B); /* S = (A *(v^u)) ^ b */ mbedtls_mpi_exp_mod(tmp1, v, u, session->ng->N, RR); mbedtls_mpi_mul_mpi(tmp2, A, tmp1); mbedtls_mpi_exp_mod(S, tmp2, b, session->ng->N, RR); hash_num(session->hash_alg, S, ver->session_key); calculate_M( session->hash_alg, session->ng, ver->M, username, s, A, B, ver->session_key ); calculate_H_AMK( session->hash_alg, ver->H_AMK, A, ver->M, ver->session_key ); *len_B = mbedtls_mpi_size(B); *bytes_B = malloc( *len_B ); if( !*bytes_B ) { free( (void*) ver->username ); free( ver ); ver = 0; *len_B = 0; goto cleanup_and_exit; } mbedtls_mpi_write_binary( B, (unsigned char *)*bytes_B, *len_B ); ver->bytes_B = *bytes_B; } cleanup_and_exit: mbedtls_mpi_free(s); free(s); mbedtls_mpi_free(v); free(v); mbedtls_mpi_free(A); free(A); if (u) {mbedtls_mpi_free(u); free(u);} if (k) {mbedtls_mpi_free(k); free(k);} mbedtls_mpi_free(B); free(B); mbedtls_mpi_free(S); free(S); mbedtls_mpi_free(b); free(b); mbedtls_mpi_free(tmp1); free(tmp1); mbedtls_mpi_free(tmp2); free(tmp2); return ver; } void srp_verifier_delete( struct SRPVerifier * ver ) { if (ver) { //delete_ng( ver->ng ); free( (char *) ver->username ); if(ver->bytes_B !=0) { 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, size_t * 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( struct SRPSession *session, const char * username, const unsigned char * bytes_password, size_t len_password) { struct SRPUser *usr = (struct SRPUser *) calloc(1, sizeof(struct SRPUser) ); size_t ulen = strlen(username) + 1; if (!usr) goto err_exit; init_random(); /* Only happens once */ usr->hash_alg = session->hash_alg; usr->ng = session->ng; usr->a = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); usr->A = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); usr->S = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(usr->a); mbedtls_mpi_init(usr->A); mbedtls_mpi_init(usr->S); if (!usr->ng || !usr->a || !usr->A || !usr->S) goto err_exit; usr->username = (const char *) malloc(ulen); 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->password, bytes_password, len_password); usr->authenticated = 0; usr->bytes_A = 0; return usr; err_exit: if (usr) { mbedtls_mpi_free(usr->a); mbedtls_mpi_free(usr->A); mbedtls_mpi_free(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 ) { mbedtls_mpi_free( usr->a ); mbedtls_mpi_free( usr->A ); mbedtls_mpi_free( usr->S ); free(usr->a); free(usr->A); free(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, size_t * 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, size_t * len_A ) { mbedtls_mpi_fill_random( usr->a, 32, &mbedtls_ctr_drbg_random, &ctr_drbg_ctx); mbedtls_mpi_exp_mod(usr->A, usr->ng->g, usr->a, usr->ng->N, RR); *len_A = mbedtls_mpi_size(usr->A); *bytes_A = malloc( *len_A ); if (!*bytes_A) { *len_A = 0; *bytes_A = 0; *username = 0; return; } mbedtls_mpi_write_binary( usr->A, (unsigned char *) *bytes_A, *len_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, size_t len_s, const unsigned char * bytes_B, size_t len_B, const unsigned char ** bytes_M, size_t * len_M ) { BIGNUM *u = 0; BIGNUM *x = 0; BIGNUM *k = 0; BIGNUM *s; s = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(s); mbedtls_mpi_read_binary(s, bytes_s, len_s); BIGNUM *B; B = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(B); mbedtls_mpi_read_binary(B, bytes_B, len_B); BIGNUM *v; v = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(v); BIGNUM *tmp1; tmp1 = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(tmp1); BIGNUM *tmp2; tmp2 = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(tmp2); BIGNUM *tmp3; tmp3 = (mbedtls_mpi *) malloc(sizeof(mbedtls_mpi)); mbedtls_mpi_init(tmp3); *len_M = 0; *bytes_M = 0; if( !s || !B || !v || !tmp1 || !tmp2 || !tmp3 ) goto cleanup_and_exit; u = H_nn(usr->hash_alg, usr->A, B); if (!u) goto cleanup_and_exit; x = calculate_x( usr->hash_alg, s, usr->username, usr->password, usr->password_len ); if (!x) goto cleanup_and_exit; k = H_nn(usr->hash_alg, usr->ng->N, usr->ng->g); if (!k) goto cleanup_and_exit; /* SRP-6a safety check */ if( mbedtls_mpi_cmp_int( B, 0 ) != 0 && mbedtls_mpi_cmp_int( u, 0 ) !=0 ) { mbedtls_mpi_exp_mod(v, usr->ng->g, x, usr->ng->N, RR); /* S = (B - k*(g^x)) ^ (a + ux) */ mbedtls_mpi_mul_mpi( tmp1, u, x ); mbedtls_mpi_mod_mpi( tmp1, tmp1, usr->ng->N); mbedtls_mpi_add_mpi( tmp2, usr->a, tmp1); mbedtls_mpi_mod_mpi( tmp2, tmp2, usr->ng->N); /* tmp2 = (a + ux) */ mbedtls_mpi_exp_mod( tmp1, usr->ng->g, x, usr->ng->N, RR); mbedtls_mpi_mul_mpi( tmp3, k, tmp1 ); mbedtls_mpi_mod_mpi( tmp3, tmp3, usr->ng->N); /* tmp3 = k*(g^x) */ mbedtls_mpi_sub_mpi(tmp1, B, tmp3); /* tmp1 = (B - K*(g^x)) */ mbedtls_mpi_exp_mod( usr->S, tmp1, tmp2, usr->ng->N, RR); hash_num(usr->hash_alg, usr->S, usr->session_key); calculate_M( usr->hash_alg, usr->ng, usr->M, usr->username, 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: mbedtls_mpi_free(s); mbedtls_mpi_free(B); mbedtls_mpi_free(u); mbedtls_mpi_free(x); mbedtls_mpi_free(k); mbedtls_mpi_free(v); mbedtls_mpi_free(tmp1); mbedtls_mpi_free(tmp2); mbedtls_mpi_free(tmp3); free(s); free(B); free(u); free(x); free(k); free(v); free(tmp1); free(tmp2); free(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; }