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Experimental encrypt-then-mac support.

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Experimental support for encrypt then mac from
draft-gutmann-tls-encrypt-then-mac-02.txt

To enable it set the appropriate extension number (0x10 for the test server)
using e.g. -DTLSEXT_TYPE_encrypt_then_mac=0x10

For non-compliant peers (i.e. just about everything) this should have no
effect.
This commit is contained in:
Dr. Stephen Henson
2013-03-22 17:12:33 +00:00
parent 226751ae4a
commit 5e3ff62c34
13 changed files with 113 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
ssl/s3_pkt.c
View File

@@ -408,6 +408,30 @@ fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
/* decrypt in place in 'rr->input' */
rr->data=rr->input;
rr->orig_len=rr->length;
/* If in encrypt-then-mac mode calculate mac from encrypted record.
* All the details below are public so no timing details can leak.
*/
if (SSL_USE_ETM(s) && s->read_hash)
{
unsigned char *mac;
mac_size=EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
if (rr->length < mac_size)
{
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
rr->length -= mac_size;
mac = rr->data + rr->length;
i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
if (i < 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
{
al=SSL_AD_BAD_RECORD_MAC;
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
goto f_err;
}
}
enc_err = s->method->ssl3_enc->enc(s,0);
/* enc_err is:
@@ -430,7 +454,7 @@ printf("\n");
/* r->length is now the compressed data plus mac */
if ((sess != NULL) &&
(s->enc_read_ctx != NULL) &&
(EVP_MD_CTX_md(s->read_hash) != NULL))
(EVP_MD_CTX_md(s->read_hash) != NULL) && !SSL_USE_ETM(s))
{
/* s->read_hash != NULL => mac_size != -1 */
unsigned char *mac = NULL;
@@ -820,7 +844,7 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
* from wr->input. Length should be wr->length.
* wr->data still points in the wb->buf */
if (mac_size != 0)
if (!SSL_USE_ETM(s) && mac_size != 0)
{
if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen]),1) < 0)
goto err;
@@ -840,6 +864,13 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
/* ssl3_enc can only have an error on read */
s->method->ssl3_enc->enc(s,1);
if (SSL_USE_ETM(s) && mac_size != 0)
{
if (s->method->ssl3_enc->mac(s,p + wr->length,1) < 0)
goto err;
wr->length+=mac_size;
}
/* record length after mac and block padding */
s2n(wr->length,plen);