/* RTMPDump - Diffie-Hellmann Key Exchange * Copyright (C) 2009 Andrej Stepanchuk * Copyright (C) 2009-2010 Howard Chu * * This file is part of librtmp. * * librtmp is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1, * or (at your option) any later version. * * librtmp is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with librtmp see the file COPYING. If not, write to * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301, USA. * http://www.gnu.org/copyleft/lgpl.html */ #include #include #include #include #include #ifdef USE_POLARSSL #include typedef mpi * MP_t; #define MP_new(m) m = malloc(sizeof(mpi)); mpi_init(m) #define MP_set_w(mpi, w) mpi_lset(mpi, w) #define MP_cmp(u, v) mpi_cmp_mpi(u, v) #define MP_set(u, v) mpi_copy(u, v) #define MP_sub_w(mpi, w) mpi_sub_int(mpi, mpi, w) #define MP_cmp_1(mpi) mpi_cmp_int(mpi, 1) #define MP_modexp(r, y, q, p) mpi_exp_mod(r, y, q, p, NULL) #define MP_free(mpi) mpi_free(mpi); free(mpi) #define MP_gethex(u, hex, res) MP_new(u); res = mpi_read_string(u, 16, hex) == 0 #define MP_bytes(u) mpi_size(u) #define MP_setbin(u,buf,len) mpi_write_binary(u,buf,len) #define MP_getbin(u,buf,len) MP_new(u); mpi_read_binary(u,buf,len) typedef struct MDH { MP_t p; MP_t g; MP_t pub_key; MP_t priv_key; long length; dhm_context ctx; } MDH; #define MDH_new() calloc(1,sizeof(MDH)) #define MDH_free(vp) {MDH *_dh = vp; dhm_free(&_dh->ctx); MP_free(_dh->p); MP_free(_dh->g); MP_free(_dh->pub_key); MP_free(_dh->priv_key); free(_dh);} static int MDH_generate_key(MDH *dh) { unsigned char out[2]; MP_set(&dh->ctx.P, dh->p); MP_set(&dh->ctx.G, dh->g); dh->ctx.len = 128; dhm_make_public(&dh->ctx, 1024, out, 1, havege_random, &RTMP_TLS_ctx->hs); MP_new(dh->pub_key); MP_new(dh->priv_key); MP_set(dh->pub_key, &dh->ctx.GX); MP_set(dh->priv_key, &dh->ctx.X); return 1; } static int MDH_compute_key(uint8_t *secret, size_t len, MP_t pub, MDH *dh) { MP_set(&dh->ctx.GY, pub); dhm_calc_secret(&dh->ctx, secret, &len); return 0; } #elif defined(USE_GNUTLS) #include #include typedef mpz_ptr MP_t; #define MP_new(m) m = malloc(sizeof(*m)); mpz_init2(m, 1) #define MP_set_w(mpi, w) mpz_set_ui(mpi, w) #define MP_cmp(u, v) mpz_cmp(u, v) #define MP_set(u, v) mpz_set(u, v) #define MP_sub_w(mpi, w) mpz_sub_ui(mpi, mpi, w) #define MP_cmp_1(mpi) mpz_cmp_ui(mpi, 1) #define MP_modexp(r, y, q, p) mpz_powm(r, y, q, p) #define MP_free(mpi) mpz_clear(mpi); free(mpi) #define MP_gethex(u, hex, res) u = malloc(sizeof(*u)); mpz_init2(u, 1); res = (mpz_set_str(u, hex, 16) == 0) #define MP_bytes(u) (mpz_sizeinbase(u, 2) + 7) / 8 #define MP_setbin(u,buf,len) nettle_mpz_get_str_256(len,buf,u) #define MP_getbin(u,buf,len) u = malloc(sizeof(*u)); mpz_init2(u, 1); nettle_mpz_set_str_256_u(u,len,buf) typedef struct MDH { MP_t p; MP_t g; MP_t pub_key; MP_t priv_key; long length; } MDH; #define MDH_new() calloc(1,sizeof(MDH)) #define MDH_free(dh) do {MP_free(((MDH*)(dh))->p); MP_free(((MDH*)(dh))->g); MP_free(((MDH*)(dh))->pub_key); MP_free(((MDH*)(dh))->priv_key); free(dh);} while(0) extern MP_t gnutls_calc_dh_secret(MP_t *priv, MP_t g, MP_t p); extern MP_t gnutls_calc_dh_key(MP_t y, MP_t x, MP_t p); #define MDH_generate_key(dh) (dh->pub_key = gnutls_calc_dh_secret(&dh->priv_key, dh->g, dh->p)) static int MDH_compute_key(uint8_t *secret, size_t len, MP_t pub, MDH *dh) { MP_t sec = gnutls_calc_dh_key(pub, dh->priv_key, dh->p); if (sec) { MP_setbin(sec, secret, len); MP_free(sec); return 0; } else return -1; } #else /* USE_OPENSSL */ #include #include typedef BIGNUM * MP_t; #define MP_new(m) m = BN_new() #define MP_set_w(mpi, w) BN_set_word(mpi, w) #define MP_cmp(u, v) BN_cmp(u, v) #define MP_set(u, v) BN_copy(u, v) #define MP_sub_w(mpi, w) BN_sub_word(mpi, w) #define MP_cmp_1(mpi) BN_cmp(mpi, BN_value_one()) #define MP_modexp(r, y, q, p) do {BN_CTX *ctx = BN_CTX_new(); BN_mod_exp(r, y, q, p, ctx); BN_CTX_free(ctx);} while(0) #define MP_free(mpi) BN_free(mpi) #define MP_gethex(u, hex, res) res = BN_hex2bn(&u, hex) #define MP_bytes(u) BN_num_bytes(u) #define MP_setbin(u,buf,len) BN_bn2bin(u,buf) #define MP_getbin(u,buf,len) u = BN_bin2bn(buf,len,0) #define MDH DH #define MDH_new() DH_new() #define MDH_free(dh) DH_free(dh) #define MDH_generate_key(dh) DH_generate_key(dh) #define MDH_compute_key(secret, seclen, pub, dh) DH_compute_key(secret, pub, dh) #endif #include "log.h" #include "dhgroups.h" /* RFC 2631, Section 2.1.5, http://www.ietf.org/rfc/rfc2631.txt */ static int isValidPublicKey(MP_t y, MP_t p, MP_t q) { int ret = TRUE; MP_t bn; assert(y); MP_new(bn); assert(bn); /* y must lie in [2,p-1] */ MP_set_w(bn, 1); if (MP_cmp(y, bn) < 0) { RTMP_Log(RTMP_LOGERROR, "DH public key must be at least 2"); ret = FALSE; goto failed; } /* bn = p-2 */ MP_set(bn, p); MP_sub_w(bn, 1); if (MP_cmp(y, bn) > 0) { RTMP_Log(RTMP_LOGERROR, "DH public key must be at most p-2"); ret = FALSE; goto failed; } /* Verify with Sophie-Germain prime * * This is a nice test to make sure the public key position is calculated * correctly. This test will fail in about 50% of the cases if applied to * random data. */ if (q) { /* y must fulfill y^q mod p = 1 */ MP_modexp(bn, y, q, p); if (MP_cmp_1(bn) != 0) { RTMP_Log(RTMP_LOGWARNING, "DH public key does not fulfill y^q mod p = 1"); } } failed: MP_free(bn); return ret; } static MDH * DHInit(int nKeyBits) { size_t res; MDH *dh = MDH_new(); if (!dh) goto failed; MP_new(dh->g); if (!dh->g) goto failed; MP_gethex(dh->p, P1024, res); /* prime P1024, see dhgroups.h */ if (!res) { goto failed; } MP_set_w(dh->g, 2); /* base 2 */ dh->length = nKeyBits; return dh; failed: if (dh) MDH_free(dh); return 0; } static int DHGenerateKey(MDH *dh) { size_t res = 0; if (!dh) return 0; while (!res) { MP_t q1 = NULL; if (!MDH_generate_key(dh)) return 0; MP_gethex(q1, Q1024, res); assert(res); res = isValidPublicKey(dh->pub_key, dh->p, q1); if (!res) { MP_free(dh->pub_key); MP_free(dh->priv_key); dh->pub_key = dh->priv_key = 0; } MP_free(q1); } return 1; } /* fill pubkey with the public key in BIG ENDIAN order * 00 00 00 00 00 x1 x2 x3 ..... */ static int DHGetPublicKey(MDH *dh, uint8_t *pubkey, size_t nPubkeyLen) { int len; if (!dh || !dh->pub_key) return 0; len = MP_bytes(dh->pub_key); if (len <= 0 || len > (int) nPubkeyLen) return 0; memset(pubkey, 0, nPubkeyLen); MP_setbin(dh->pub_key, pubkey + (nPubkeyLen - len), len); return 1; } #if 0 /* unused */ static int DHGetPrivateKey(MDH *dh, uint8_t *privkey, size_t nPrivkeyLen) { if (!dh || !dh->priv_key) return 0; int len = MP_bytes(dh->priv_key); if (len <= 0 || len > (int) nPrivkeyLen) return 0; memset(privkey, 0, nPrivkeyLen); MP_setbin(dh->priv_key, privkey + (nPrivkeyLen - len), len); return 1; } #endif /* computes the shared secret key from the private MDH value and the * other party's public key (pubkey) */ static int DHComputeSharedSecretKey(MDH *dh, uint8_t *pubkey, size_t nPubkeyLen, uint8_t *secret) { MP_t q1 = NULL, pubkeyBn = NULL; size_t len; int res; if (!dh || !secret || nPubkeyLen >= INT_MAX) return -1; MP_getbin(pubkeyBn, pubkey, nPubkeyLen); if (!pubkeyBn) return -1; MP_gethex(q1, Q1024, len); assert(len); if (isValidPublicKey(pubkeyBn, dh->p, q1)) res = MDH_compute_key(secret, nPubkeyLen, pubkeyBn, dh); else res = -1; MP_free(q1); MP_free(pubkeyBn); return res; }