[tcpm] tcp-auth-opt issue: replay protection
Joe Touch <touch@ISI.EDU> Wed, 30 July 2008 22:23 UTC
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From: Joe Touch <touch@ISI.EDU>
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Subject: [tcpm] tcp-auth-opt issue: replay protection
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Given Eric's points on this topic, as a way forward, there are a few alternatives (comments requested) 1. assume the key management system (KMS) will rollover the keys every 2^31 bytes Eric noted this is weak, since we cannot rely on the KMS to act on this without other info. Let's presume this is unacceptable to the WG and move on... 2. include an extended sequence number (ESN) inside TCP-AO ESN starts at 0 increment ESN when the TCP sequence number rolls over* passed ESN to the encryption algorithm as part of the MAC'd data 3. have TCP-AO ask the KMS to add a new key for the connection when the sequence number rolls over (actually just before, e.g., 2^31 rolls over) - ------------------------------------ #2 is internal to TCP-AO, i.e., it requires no 'callback' to the KMS There appears to be a synchronization issue here - exactly when is the ESN incremented? Suppose endpoints A and B; there are two ESNs - ESN_ab and ESN_ba: A increments ESN_ab when A receives an ack from B w/seqno > 2^31 B increments ESN_ab when B sends an ack to A w/seqno > 2^31 B increments ESN_ba when B receives an ack from A w/seqno > 2^31 A increments ESN_ba when A sends an ack to B w/seqno > 2^31 i.e., the ESN is incremented when the reverse channel succeeds; we can't use the forward channel, since one side would change the ESN in ways the other would never notice (it wouldn't decode it) Given that algorithm, every ESN increment would trash data in transit from A-B. Is there an algorithm that does not do this? - ------------------------------------- #3 allows packets to be reordered without loss during key rollover, and is not susceptible to the burst-losses of #2 Note that #2 should not 'insert a key into the TSAD' - that interface should be under the exclusive control of the KMS - at which point asking the KMS to keep that info (or bury it in the TSAD where the KMS can refer to it) seems sufficient. Comments? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkiQ6a4ACgkQE5f5cImnZruZ7ACfRfobhbIZYd/t4xZinRjqMNHp AwgAn0hNl3OS50CRmx35wngpGrUBzqfo =DPd7 -----END PGP SIGNATURE----- _______________________________________________ tcpm mailing list tcpm@ietf.org https://www.ietf.org/mailman/listinfo/tcpm
- [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt-01 Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Adam Langley
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Adam Langley
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Adam Langley
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Anantha Ramaiah (ananth)
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Anantha Ramaiah (ananth)
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Anantha Ramaiah (ananth)
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Caitlin Bestler
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Joe Touch
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Lars Eggert
- Re: [tcpm] Review of draft-ietf-tcpm-tcp-auth-opt… Eric Rescorla
- [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Adam Langley
- Re: [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Adam Langley
- Re: [tcpm] tcp-auth-opt issue: replay protection Eric Rescorla
- Re: [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Adam Langley
- Re: [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Lars Eggert
- Re: [tcpm] tcp-auth-opt issue: replay protection Eric Rescorla
- Re: [tcpm] tcp-auth-opt issue: replay protection Lars Eggert
- Re: [tcpm] tcp-auth-opt issue: replay protection Anantha Ramaiah (ananth)
- Re: [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Eddy, Wesley M. (GRC-RCN0)[VZ]
- Re: [tcpm] tcp-auth-opt issue: replay protection Adam Langley
- Re: [tcpm] tcp-auth-opt issue: replay protection Caitlin Bestler
- Re: [tcpm] tcp-auth-opt issue: replay protection Joe Touch
- Re: [tcpm] tcp-auth-opt issue: replay protection Ron Bonica