1. Simple Authentication schemes for ALC and NORM draft-ietf-rmt-simple-auth-for-alc-norm-00 IETF 73 – Minneapolis, November 2008 Vincent Roca (INRIA)

2. General now a WG Item document mas decided during IETF71 summary of the proposal mthis I-D and TESLA I-D introduce several packet- level sender authentication/integrity check schemes for ALC and NORM mall of them define specific EXT_AUTH header extensions, one per authentication scheme

3. General… (cont’) mthese HE start by the same ASID (Auth Scheme ID) 4-bit field: mgoal is to enable a mixed use of these schemes in the same session, even on the same communication path: e.g., TESLA for downstream NORM traffic, and Group MAC for the upstream traffic mthe ASID/auth. scheme mapping is communicated out-of-band, as part of the session description mthere is no fixed IANA value 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ASID | HET (=1) | HEL | ASID | … (scheme specific) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4. Record of the changes RSA digital signatures madded text detailing how to use RSA signatures mas in TESLA I-D mwe also mention SHA-256 (rather than SHA-1) mcorrected a mistake: mthe parameters to be communicated to the receivers must include the signature crypto function (e.g., SHA- 256)

5. Record of the changes… (cont’) ECC (elliptic curve crypto) digital signatures madded discussion in introduction mhigher performances than RSA-based signatures (see RMT Security discussion I-D) mbut patent claims exist mwe mention ECC but do not define any scheme for them mQUESTION: should we detail the use of ECC or leave it open for a future (tiny) document?

6. Record of the changes… (cont’) Group MAC mclarified that SHA-256 is recommended mclarified that during HMAC-SHA* output truncation, we need to keep the MSB

7. Record of the changes… (cont’) Combined use of Group MAC/Digital Signatures mBEFORE: use two separate EXT_AUTH HE mNOW: a specific EXT_AUTH HE, that gathers the signature + the Group MAC fields mmotivated by ma lower overhead (32 bits smaller) ma clear specification that Group MAC encompasses the digital signature field (calculated first) Security section added madapted from that of TESLA I-D

8. Next steps probably a new version mespecially if ECC is included and then WGLC