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Implement EtM

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This commit is contained in:
Manuel Pégourié-Gonnard 2014-10-29 12:07:57 +01:00
parent 0098e7dc70
commit 313d796e80
1 changed files with 83 additions and 15 deletions
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98
library/ssl_tls.c
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@ -1115,8 +1115,7 @@ static int ssl_encrypt_buf( ssl_context *ssl )
#if defined(POLARSSL_ARC4_C) || defined(POLARSSL_CIPHER_NULL_CIPHER) || \
( defined(POLARSSL_CIPHER_MODE_CBC) && \
( defined(POLARSSL_AES_C) || defined(POLARSSL_CAMELLIA_C) ) )
if( mac_order == MAC_PLAINTEXT
|| mac_order == MAC_CIPHERTEXT ) // WIP!
if( mac_order == MAC_PLAINTEXT )
{
#if defined(POLARSSL_SSL_PROTO_SSL3)
if( ssl->minor_ver == SSL_MINOR_VERSION_0 )
@ -1350,6 +1349,36 @@ static int ssl_encrypt_buf( ssl_context *ssl )
ssl->transform_out->ivlen );
}
#endif
#if defined(POLARSSL_SSL_ENCRYPT_THEN_MAC)
if( mac_order == MAC_CIPHERTEXT )
{
/*
* MAC(MAC_write_key, seq_num +
* TLSCipherText.type +
* TLSCipherText.version +
* TLSCipherText.length +
* IV + // except for TLS 1.0
* ENC(content + padding + padding_length));
*/
size_t final_len = ssl->out_msglen + ssl->transform_out->maclen;
unsigned char pseudo_hdr[13];
memcpy( pseudo_hdr + 0, ssl->out_ctr, 8 );
memcpy( pseudo_hdr + 8, ssl->out_hdr, 3 );
pseudo_hdr[11] = (unsigned char)( ( final_len >> 8 ) & 0xFF );
pseudo_hdr[12] = (unsigned char)( ( final_len ) & 0xFF );
md_hmac_update( &ssl->transform_out->md_ctx_enc, pseudo_hdr, 13 );
md_hmac_update( &ssl->transform_out->md_ctx_enc,
ssl->out_iv, ssl->out_msglen );
md_hmac_finish( &ssl->transform_out->md_ctx_enc,
ssl->out_iv + ssl->out_msglen );
md_hmac_reset( &ssl->transform_out->md_ctx_enc );
ssl->out_msglen += ssl->transform_out->maclen;
}
#endif /* POLARSSL_SSL_ENCRYPT_THEN_MAC */
}
else
#endif /* POLARSSL_CIPHER_MODE_CBC &&
@ -1399,7 +1428,6 @@ static int ssl_decrypt_buf( ssl_context *ssl )
}
mac_order = ssl_get_mac_order( ssl, ssl->session_in, mode );
(void) mac_order; // WIP
#if defined(POLARSSL_ARC4_C) || defined(POLARSSL_CIPHER_NULL_CIPHER)
if( mode == POLARSSL_MODE_STREAM )
@ -1516,13 +1544,6 @@ static int ssl_decrypt_buf( ssl_context *ssl )
/*
* Check immediate ciphertext sanity
*/
if( ssl->in_msglen % ssl->transform_in->ivlen != 0 )
{
SSL_DEBUG_MSG( 1, ( "msglen (%d) %% ivlen (%d) != 0",
ssl->in_msglen, ssl->transform_in->ivlen ) );
return( POLARSSL_ERR_SSL_INVALID_MAC );
}
#if defined(POLARSSL_SSL_PROTO_TLS1_1) || defined(POLARSSL_SSL_PROTO_TLS1_2)
if( ssl->minor_ver >= SSL_MINOR_VERSION_2 )
minlen += ssl->transform_in->ivlen;
@ -1542,6 +1563,50 @@ static int ssl_decrypt_buf( ssl_context *ssl )
dec_msg = ssl->in_msg;
dec_msg_result = ssl->in_msg;
/*
* Authenticate before decrypt if enabled
*/
#if defined(POLARSSL_SSL_ENCRYPT_THEN_MAC)
if( mac_order == MAC_CIPHERTEXT )
{
unsigned char computed_mac[POLARSSL_SSL_MAX_MAC_SIZE];
dec_msglen -= ssl->transform_in->maclen;
ssl->in_msglen -= ssl->transform_in->maclen;
// TODO: adjust for DTLS
md_hmac_update( &ssl->transform_in->md_ctx_dec,
ssl->in_ctr, 13 );
md_hmac_update( &ssl->transform_in->md_ctx_dec,
ssl->in_iv, ssl->in_msglen );
md_hmac_finish( &ssl->transform_in->md_ctx_dec, computed_mac );
md_hmac_reset( &ssl->transform_in->md_ctx_dec );
SSL_DEBUG_BUF( 4, "message mac", ssl->in_iv + ssl->in_msglen,
ssl->transform_in->maclen );
SSL_DEBUG_BUF( 4, "computed mac", computed_mac,
ssl->transform_in->maclen );
if( safer_memcmp( ssl->in_iv + ssl->in_msglen, computed_mac,
ssl->transform_in->maclen ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
return( POLARSSL_ERR_SSL_INVALID_MAC );
}
}
#endif /* POLARSSL_SSL_ENCRYPT_THEN_MAC */
/*
* Check length sanity
*/
if( ssl->in_msglen % ssl->transform_in->ivlen != 0 )
{
SSL_DEBUG_MSG( 1, ( "msglen (%d) %% ivlen (%d) != 0",
ssl->in_msglen, ssl->transform_in->ivlen ) );
return( POLARSSL_ERR_SSL_INVALID_MAC );
}
#if defined(POLARSSL_SSL_PROTO_TLS1_1) || defined(POLARSSL_SSL_PROTO_TLS1_2)
/*
* Initialize for prepended IV for block cipher in TLS v1.1 and up
@ -1586,7 +1651,8 @@ static int ssl_decrypt_buf( ssl_context *ssl )
padlen = 1 + ssl->in_msg[ssl->in_msglen - 1];
if( ssl->in_msglen < ssl->transform_in->maclen + padlen )
if( ssl->in_msglen < ssl->transform_in->maclen + padlen &&
mac_order == MAC_PLAINTEXT )
{
#if defined(POLARSSL_SSL_DEBUG_ALL)
SSL_DEBUG_MSG( 1, ( "msglen (%d) < maclen (%d) + padlen (%d)",
@ -1660,6 +1726,8 @@ static int ssl_decrypt_buf( ssl_context *ssl )
SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( POLARSSL_ERR_SSL_INTERNAL_ERROR );
}
ssl->in_msglen -= padlen;
}
else
#endif /* POLARSSL_CIPHER_MODE_CBC &&
@ -1673,17 +1741,17 @@ static int ssl_decrypt_buf( ssl_context *ssl )
ssl->in_msg, ssl->in_msglen );
/*
* Always compute the MAC (RFC4346, CBCTIME), except for AEAD of course
* Authenticate if not done yet.
* Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
*/
#if defined(POLARSSL_ARC4_C) || defined(POLARSSL_CIPHER_NULL_CIPHER) || \
( defined(POLARSSL_CIPHER_MODE_CBC) && \
( defined(POLARSSL_AES_C) || defined(POLARSSL_CAMELLIA_C) ) )
if( mode != POLARSSL_MODE_GCM &&
mode != POLARSSL_MODE_CCM )
if( mac_order == MAC_PLAINTEXT )
{
unsigned char tmp[POLARSSL_SSL_MAX_MAC_SIZE];
ssl->in_msglen -= ( ssl->transform_in->maclen + padlen );
ssl->in_msglen -= ssl->transform_in->maclen;
ssl->in_hdr[3] = (unsigned char)( ssl->in_msglen >> 8 );
ssl->in_hdr[4] = (unsigned char)( ssl->in_msglen );