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