t1_enc.c

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/* ssl/t1_enc.c */
/* Copyright (C) 1995-1998 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson ([e-mail]).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young ([e-mail])"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson ([e-mail])"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <openssl/comp.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include "ssl_locl.h"

static void tls1_P_hash(const EVP_MD *md, const unsigned char *sec,
			int sec_len, unsigned char *seed, int seed_len,
			unsigned char *out, int olen)
	{
	int chunk,n;
	unsigned int j;
	HMAC_CTX ctx;
	HMAC_CTX ctx_tmp;
	unsigned char A1[HMAC_MAX_MD_CBLOCK];
	unsigned int A1_len;
	
	chunk=EVP_MD_size(md);

	HMAC_Init(&ctx,sec,sec_len,md);
	HMAC_Update(&ctx,seed,seed_len);
	HMAC_Final(&ctx,A1,&A1_len);

	n=0;
	for (;;)
		{
		HMAC_Init(&ctx,NULL,0,NULL); /* re-init */
		HMAC_Update(&ctx,A1,A1_len);
		memcpy(&ctx_tmp,&ctx,sizeof(ctx)); /* Copy for A2 */ /* not needed for last one */
		HMAC_Update(&ctx,seed,seed_len);

		if (olen > chunk)
			{
			HMAC_Final(&ctx,out,&j);
			out+=j;
			olen-=j;
			HMAC_Final(&ctx_tmp,A1,&A1_len); /* calc the next A1 value */
			}
		else	/* last one */
			{
			HMAC_Final(&ctx,A1,&A1_len);
			memcpy(out,A1,olen);
			break;
			}
		}
	HMAC_cleanup(&ctx);
	HMAC_cleanup(&ctx_tmp);
	memset(A1,0,sizeof(A1));
	}

static void tls1_PRF(const EVP_MD *md5, const EVP_MD *sha1,
		     unsigned char *label, int label_len,
		     const unsigned char *sec, int slen, unsigned char *out1,
		     unsigned char *out2, int olen)
	{
	int len,i;
	const unsigned char *S1,*S2;

	len=slen/2;
	S1=sec;
	S2= &(sec[len]);
	len+=(slen&1); /* add for odd, make longer */

	
	tls1_P_hash(md5 ,S1,len,label,label_len,out1,olen);
	tls1_P_hash(sha1,S2,len,label,label_len,out2,olen);

	for (i=0; i<olen; i++)
		out1[i]^=out2[i];
	}

static void tls1_generate_key_block(SSL *s, unsigned char *km,
	     unsigned char *tmp, int num)
	{
	unsigned char *p;
	unsigned char buf[SSL3_RANDOM_SIZE*2+
		TLS_MD_MAX_CONST_SIZE];
	p=buf;

	memcpy(p,TLS_MD_KEY_EXPANSION_CONST,
		TLS_MD_KEY_EXPANSION_CONST_SIZE);
	p+=TLS_MD_KEY_EXPANSION_CONST_SIZE;
	memcpy(p,s->s3->server_random,SSL3_RANDOM_SIZE);
	p+=SSL3_RANDOM_SIZE;
	memcpy(p,s->s3->client_random,SSL3_RANDOM_SIZE);
	p+=SSL3_RANDOM_SIZE;

	tls1_PRF(s->ctx->md5,s->ctx->sha1,buf,(int)(p-buf),
		 s->session->master_key,s->session->master_key_length,
		 km,tmp,num);
	}

int tls1_change_cipher_state(SSL *s, int which)
	{
	static const unsigned char empty[]="";
	unsigned char *p,*key_block,*mac_secret;
	unsigned char *exp_label,buf[TLS_MD_MAX_CONST_SIZE+
		SSL3_RANDOM_SIZE*2];
	unsigned char tmp1[EVP_MAX_KEY_LENGTH];
	unsigned char tmp2[EVP_MAX_KEY_LENGTH];
	unsigned char iv1[EVP_MAX_IV_LENGTH*2];
	unsigned char iv2[EVP_MAX_IV_LENGTH*2];
	unsigned char *ms,*key,*iv,*er1,*er2;
	int client_write;
	EVP_CIPHER_CTX *dd;
	const EVP_CIPHER *c;
	const SSL_COMP *comp;
	const EVP_MD *m;
	int _exp,n,i,j,k,exp_label_len,cl;

	_exp=SSL_C_IS_EXPORT(s->s3->tmp.new_cipher);
	c=s->s3->tmp.new_sym_enc;
	m=s->s3->tmp.new_hash;
	comp=s->s3->tmp.new_compression;
	key_block=s->s3->tmp.key_block;

	if (which & SSL3_CC_READ)
		{
		if ((s->enc_read_ctx == NULL) &&
			((s->enc_read_ctx=(EVP_CIPHER_CTX *)
			OPENSSL_malloc(sizeof(EVP_CIPHER_CTX))) == NULL))
			goto err;
		dd= s->enc_read_ctx;
		s->read_hash=m;
		if (s->expand != NULL)
			{
			COMP_CTX_free(s->expand);
			s->expand=NULL;
			}
		if (comp != NULL)
			{
			s->expand=COMP_CTX_new(comp->method);
			if (s->expand == NULL)
				{
				SSLerr(SSL_F_TLS1_CHANGE_CIPHER_STATE,SSL_R_COMPRESSION_LIBRARY_ERROR);
				goto err2;
				}
			if (s->s3->rrec.comp == NULL)
				s->s3->rrec.comp=(unsigned char *)
					OPENSSL_malloc(SSL3_RT_MAX_ENCRYPTED_LENGTH);
			if (s->s3->rrec.comp == NULL)
				goto err;
			}
		memset(&(s->s3->read_sequence[0]),0,8);
		mac_secret= &(s->s3->read_mac_secret[0]);
		}
	else
		{
		if ((s->enc_write_ctx == NULL) &&
			((s->enc_write_ctx=(EVP_CIPHER_CTX *)
			OPENSSL_malloc(sizeof(EVP_CIPHER_CTX))) == NULL))
			goto err;
		dd= s->enc_write_ctx;
		s->write_hash=m;
		if (s->compress != NULL)
			{
			COMP_CTX_free(s->compress);
			s->compress=NULL;
			}
		if (comp != NULL)
			{
			s->compress=COMP_CTX_new(comp->method);
			if (s->compress == NULL)
				{
				SSLerr(SSL_F_TLS1_CHANGE_CIPHER_STATE,SSL_R_COMPRESSION_LIBRARY_ERROR);
				goto err2;
				}
			}
		memset(&(s->s3->write_sequence[0]),0,8);
		mac_secret= &(s->s3->write_mac_secret[0]);
		}

	EVP_CIPHER_CTX_init(dd);

	p=s->s3->tmp.key_block;
	i=EVP_MD_size(m);
	cl=EVP_CIPHER_key_length(c);
	j=_exp ? (cl < SSL_C_EXPORT_KEYLENGTH(s->s3->tmp.new_cipher) ?
		  cl : SSL_C_EXPORT_KEYLENGTH(s->s3->tmp.new_cipher)) : cl;
	/* Was j=(exp)?5:EVP_CIPHER_key_length(c); */
	k=EVP_CIPHER_iv_length(c);
	er1= &(s->s3->client_random[0]);
	er2= &(s->s3->server_random[0]);
	if (	(which == SSL3_CHANGE_CIPHER_CLIENT_WRITE) ||
		(which == SSL3_CHANGE_CIPHER_SERVER_READ))
		{
		ms=  &(p[ 0]); n=i+i;
		key= &(p[ n]); n+=j+j;
		iv=  &(p[ n]); n+=k+k;
		exp_label=(unsigned char *)TLS_MD_CLIENT_WRITE_KEY_CONST;
		exp_label_len=TLS_MD_CLIENT_WRITE_KEY_CONST_SIZE;
		client_write=1;
		}
	else
		{
		n=i;
		ms=  &(p[ n]); n+=i+j;
		key= &(p[ n]); n+=j+k;
		iv=  &(p[ n]); n+=k;
		exp_label=(unsigned char *)TLS_MD_SERVER_WRITE_KEY_CONST;
		exp_label_len=TLS_MD_SERVER_WRITE_KEY_CONST_SIZE;
		client_write=0;
		}

	if (n > s->s3->tmp.key_block_length)
		{
		SSLerr(SSL_F_TLS1_CHANGE_CIPHER_STATE,SSL_R_INTERNAL_ERROR);
		goto err2;
		}

	memcpy(mac_secret,ms,i);
#ifdef TLS_DEBUG
printf("which = %04X\nmac key=",which);
{ int z; for (z=0; z<i; z++) printf("%02X%c",ms[z],((z+1)%16)?' ':'\n'); }
#endif
	if (_exp)
		{
		/* In here I set both the read and write key/iv to the
		 * same value since only the correct one will be used :-).
		 */
		p=buf;
		memcpy(p,exp_label,exp_label_len);
		p+=exp_label_len;
		memcpy(p,s->s3->client_random,SSL3_RANDOM_SIZE);
		p+=SSL3_RANDOM_SIZE;
		memcpy(p,s->s3->server_random,SSL3_RANDOM_SIZE);
		p+=SSL3_RANDOM_SIZE;
		tls1_PRF(s->ctx->md5,s->ctx->sha1,buf,(int)(p-buf),key,j,
			 tmp1,tmp2,EVP_CIPHER_key_length(c));
		key=tmp1;

		if (k > 0)
			{
			p=buf;
			memcpy(p,TLS_MD_IV_BLOCK_CONST,
				TLS_MD_IV_BLOCK_CONST_SIZE);
			p+=TLS_MD_IV_BLOCK_CONST_SIZE;
			memcpy(p,s->s3->client_random,SSL3_RANDOM_SIZE);
			p+=SSL3_RANDOM_SIZE;
			memcpy(p,s->s3->server_random,SSL3_RANDOM_SIZE);
			p+=SSL3_RANDOM_SIZE;
			tls1_PRF(s->ctx->md5,s->ctx->sha1,buf,p-buf,empty,0,
				 iv1,iv2,k*2);
			if (client_write)
				iv=iv1;
			else
				iv= &(iv1[k]);
			}
		}

	s->session->key_arg_length=0;

	EVP_CipherInit(dd,c,key,iv,(which & SSL3_CC_WRITE));
#ifdef TLS_DEBUG
printf("which = %04X\nkey=",which);
{ int z; for (z=0; z<EVP_CIPHER_key_length(c); z++) printf("%02X%c",key[z],((z+1)%16)?' ':'\n'); }
printf("\niv=");