[Cfrg] Request For Opinions

[jsjoberg@toplayer.com]

Hey all,

I'm in an ETSI working group and we are trying to find a way to provide
integrity checks along with non-repudiation on a theoretically infinite
amount of data delivered over a network at 10's to 100's Mbps.
Crypto-hardware is not a reasonable expectation and the solution is
extremely cost sensitive.  

The data link will be sending PDU's an an as need basis, with each PDU being
tagged with a sequence number.  At some point later in time
(days/weeks/years) we need to be able to prove the integrity of the PDU's as
well as the authenticity.

The following is what we have come up with and I'm wondering if anyone has
anything to add, remove, or change that would make a better solution.  The
idea is to get some of the authentication strength of DSS/DSA without the
full strength or the full cost (in processing time).

Thanks in advance for any input,
Jon

Periodically, hashes over the data PDUs will be inserted into the data
stream. A hash will only be created if at least one PDU packet was sent
since the last hash was sent or since startup.

Every <n1> PDU packets or when <t1> seconds have passed a MD5 hash is
generated over all PDU
packets sent since the last MD5 hash was sent or since startup. The MD5 hash
is sent in a HashPDU, where the HashSequenceNr increments for every hash
sent for this intercept. The array PDUSequenceNrsIncluded contains the
sequence number of every data PDU that was included in the hash.

NOTE: The values for n1 and t1 are configurable. 

Periodically, a hash over the hashes specified above and a signature of that
hash, will be inserted into the  the data stream. The signed hashes allows
authentication of the sender and to verfify the integrity of the recevied
MD5 hashes.

Every <n2> hashes or when <t2> seconds have passed, a MD5 hash is generated
over all hashes sent since the last signed hash was sent or since startup
and that MD5 hash is signed
using DSS/DSA. The MD5 hash and corresponding DSS/DSA signature are sent
over in a SignedHashPDU, where the SignedHashSequenceNr increments for every
signed hash sent. The array HashSequenceNrsIncluded contains the sequence
number of every HashPDU that
was included in the signed hash.

NOTE: The values for n2 and t2 are configurable.

NOTE: The distribution of the DSS/DSA public key is outside the scope of
this specification.

_______________________________________________
Cfrg mailing list
Cfrg@ietf.org
https://www1.ietf.org/mailman/listinfo/cfrg