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Re: [quicwg/base-drafts] Bring back AEAD_AES_128_CCM_8 now that we pad the plaintext (#2581)

Martin Thomson <notifications@github.com> Wed, 15 May 2019 03:22 UTC

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Subject: Re: [quicwg/base-drafts] Bring back AEAD_AES_128_CCM_8 now that we pad the plaintext (#2581)
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I don't think that we need this.  The reasons offered thus far amount to "because we can".  I'd like to see some analysis suggesting that shorter authentication tags are OK in the general case.  Or text explaining constraints on deployments that choose to use a shorter tag.

I understand the benefits of CCM over GCM; I understand that this includes an ability to have a shorter tag, unlike GCM which fails badly.  I understand the desire to save bits.  But it isn't really that many bits, and the shorter tag changes the odds of an invalid packet being accepted fairly significantly.

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