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Encrypt session tickets

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Manuel Pégourié-Gonnard 2013-08-03 15:37:58 +02:00 committed by Paul Bakker
parent 779e42982c
commit 990c51a557
3 changed files with 87 additions and 24 deletions
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3
include/polarssl/ssl.h
View File

@ -35,6 +35,7 @@
#include "sha1.h"
#include "sha256.h"
#include "sha512.h"
#include "aes.h"
#include "ssl_ciphersuites.h"
@ -452,6 +453,8 @@ struct _ssl_handshake_params
struct _ssl_ticket_keys
{
unsigned char key_name[16]; /*!< name to quickly discard bad tickets */
aes_context enc; /*!< encryption context */
aes_context dec; /*!< decryption context */
};
struct _ssl_context

100
library/ssl_srv.c
View File

@ -161,36 +161,56 @@ static int ssl_load_session( ssl_session *session,
*/
static int ssl_write_ticket( ssl_context *ssl, size_t *tlen )
{
int ret;
unsigned char * const start = ssl->out_msg + 10;
unsigned char *p = start;
size_t clear_len, enc_len;
unsigned char *state;
unsigned char iv[16];
size_t clear_len, enc_len, pad_len, i;
if( ssl->ticket_keys == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
/* Write key name */
memcpy( p, ssl->ticket_keys->key_name, 16 );
p += 16;
memset( p, 0, 16 ); // TODO: iv
/* Generate and write IV (with a copy for aes_crypt) */
if( ( ret = ssl->f_rng( ssl->p_rng, p, 16 ) ) != 0 )
return( ret );
memcpy( iv, p, 16 );
p += 16;
ssl_save_session( ssl->session_negotiate, p + 2, &clear_len );
SSL_DEBUG_BUF( 4, "session ticket cleartext", p, clear_len );
/* Dump session state */
state = p + 2;
ssl_save_session( ssl->session_negotiate, state, &clear_len );
SSL_DEBUG_BUF( 3, "session ticket cleartext", state, clear_len );
// TODO: encrypt ticket
enc_len = clear_len;
(void) enc_len;
/* Apply PKCS padding */
pad_len = 16 - clear_len % 16;
enc_len = clear_len + pad_len;
for( i = clear_len; i < enc_len; i++ )
state[i] = (unsigned char) pad_len;
*p++ = (unsigned char)( ( clear_len >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( clear_len ) & 0xFF );
p += clear_len;
/* Encrypt */
if( ( ret = aes_crypt_cbc( &ssl->ticket_keys->enc, AES_ENCRYPT,
enc_len, iv, state, state ) ) != 0 )
{
return( ret );
}
memset( p, 0, 32 ); // TODO: mac
/* Write length */
*p++ = (unsigned char)( ( enc_len >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( enc_len ) & 0xFF );
p = state + enc_len;
/* Compute and write MAC */
memset( p, 0, 32 );
p += 32;
*tlen = p - start;
SSL_DEBUG_BUF( 4, "final session ticket", start, *tlen );
SSL_DEBUG_BUF( 3, "session ticket structure", start, *tlen );
return( 0 );
}
@ -199,17 +219,20 @@ static int ssl_write_ticket( ssl_context *ssl, size_t *tlen )
* Load session ticket (see ssl_write_ticket for structure)
*/
static int ssl_parse_ticket( ssl_context *ssl,
const unsigned char *buf,
unsigned char *buf,
size_t len )
{
int ret;
ssl_session session;
const unsigned char *key_name = buf;
const unsigned char *iv = buf + 16;
const unsigned char *enc_len_p = iv + 16;
const unsigned char *ticket = enc_len_p + 2;
const unsigned char *mac;
size_t enc_len, clear_len;
unsigned char *key_name = buf;
unsigned char *iv = buf + 16;
unsigned char *enc_len_p = iv + 16;
unsigned char *ticket = enc_len_p + 2;
unsigned char *mac;
size_t enc_len, clear_len, i;
unsigned char pad_len;
SSL_DEBUG_BUF( 3, "session ticket structure", buf, len );
if( len < 34 || ssl->ticket_keys == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
@ -220,15 +243,35 @@ static int ssl_parse_ticket( ssl_context *ssl,
if( len != enc_len + 66 )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
/* Check name */
if( memcmp( key_name, ssl->ticket_keys->key_name, 16 ) != 0 )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
// TODO: check hmac
(void) mac;
// TODO: decrypt ticket
clear_len = enc_len;
/* Decrypt */
if( ( ret = aes_crypt_cbc( &ssl->ticket_keys->dec, AES_DECRYPT,
enc_len, iv, ticket, ticket ) ) != 0 )
{
return( ret );
}
/* Check PKCS padding */
pad_len = ticket[enc_len - 1];
ret = 0;
for( i = 2; i < pad_len; i++ )
if( ticket[enc_len - i] != pad_len )
ret = POLARSSL_ERR_SSL_BAD_INPUT_DATA;
if( ret != 0 )
return( ret );
clear_len = enc_len - pad_len;
SSL_DEBUG_BUF( 3, "session ticket cleartext", ticket, clear_len );
/* Actually load session */
if( ( ret = ssl_load_session( &session, ticket, clear_len ) ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "failed to parse ticket content" ) );
@ -534,9 +577,11 @@ static int ssl_parse_truncated_hmac_ext( ssl_context *ssl,
}
static int ssl_parse_session_ticket_ext( ssl_context *ssl,
const unsigned char *buf,
unsigned char *buf,
size_t len )
{
int ret;
if( ssl->session_tickets == SSL_SESSION_TICKETS_DISABLED )
return( 0 );
@ -557,8 +602,11 @@ static int ssl_parse_session_ticket_ext( ssl_context *ssl,
/*
* Failures are ok: just ignore the ticket and proceed.
*/
if( ssl_parse_ticket( ssl, buf, len ) != 0 )
if( ( ret = ssl_parse_ticket( ssl, buf, len ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ssl_parse_ticket", ret );
return( 0 );
}
SSL_DEBUG_MSG( 3, ( "session successfully restored from ticket" ) );
@ -2438,7 +2486,11 @@ static int ssl_write_new_session_ticket( ssl_context *ssl )
ssl->out_msg[6] = 0x00;
ssl->out_msg[7] = 0x00;
ssl_write_ticket( ssl, &tlen );
if( ( ret = ssl_write_ticket( ssl, &tlen ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ssl_write_ticket", ret );
tlen = 0;
}
ssl->out_msg[8] = (unsigned char)( ( tlen >> 8 ) & 0xFF );
ssl->out_msg[9] = (unsigned char)( ( tlen ) & 0xFF );

8
library/ssl_tls.c
View File

@ -2979,6 +2979,7 @@ static int ssl_ticket_keys_init( ssl_context *ssl )
{
int ret;
ssl_ticket_keys *tkeys;
unsigned char buf[32];
if( ssl->ticket_keys != NULL )
return( 0 );
@ -2989,6 +2990,13 @@ static int ssl_ticket_keys_init( ssl_context *ssl )
if( ( ret = ssl->f_rng( ssl->p_rng, tkeys->key_name, 16 ) ) != 0 )
return( ret );
if( ( ret = ssl->f_rng( ssl->p_rng, buf, 16 ) ) != 0 ||
( ret = aes_setkey_enc( &tkeys->enc, buf, 128 ) ) != 0 ||
( ret = aes_setkey_dec( &tkeys->dec, buf, 128 ) ) != 0 )
{
return( ret );
}
ssl->ticket_keys = tkeys;
return( 0 );