hi, thanks for your quick reply. So if I can include the sequence number as a part of the protocol(may be another field added by the SSL) data, I still solve the problem of replay attacks and I can get rid of sequence number from the MAC calculation. So my MAC wouldnt depend on the sequence number now. To avoid replay attacks there are 2 options: 1. As it exists now. MAC would fail with duplicate packets. 2. Or if sequence number is made a part of the protocol and stripped of the MAC calulation, I can verify and avoid duplicate packets from the sequence number which could be made a part of the protocol data (even though the MAC would succeed). This is just as the way TCP works.
If I'm wrong in any of these points please do correct me. Thanks again Lev for your quick reply. -swami On Wed, 19 Nov 2003, Lev Walkin wrote: > Swaminathan P wrote: > > I have a question anout the use of sequence number as a part of the > > input to the hash function during the MAC calculation. Does that security > > concerns? Would the security aspects of theSSL be affected if the sequence > > number is not used as a part of the input to the hash funtion for MAC > > calculation? > > Sequence number prevents replay attacks. Both sides of SSL communication > channel are keeping track of number of messages received. If somebody > has ability to inject a record into the SSL stream which is the same > as some other record observed on that stream, the sequence number melted > in a MAC will prevent the SSL machinery to treat this record as a valid one. > > > -- > Lev Walkin > [EMAIL PROTECTED] > > ______________________________________________________________________ > OpenSSL Project http://www.openssl.org > Development Mailing List [EMAIL PROTECTED] > Automated List Manager [EMAIL PROTECTED] > ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]
