[AVTCORE] Comments on the draft-ietf-avtcore-srtp-aes-gcm-06

Woo-Hwan Kim <whkim5@ensec.re.kr> Thu, 27 June 2013 05:22 UTC

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Date: Thu, 27 Jun 2013 14:22:38 +0900
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From: Woo-Hwan Kim <whkim5@ensec.re.kr>
To: avt@ietf.org, draft-ietf-avtcore-srtp-aes-gcm@tools.ietf.org
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Cc: Magnus Westerlund <magnus.westerlund@ericsson.com>, Daesung Kwon <ds_kwon@ensec.re.kr>, Je Hong Park <jhpark@ensec.re.kr>
Subject: [AVTCORE] Comments on the draft-ietf-avtcore-srtp-aes-gcm-06
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Here are some comments on the draft-ietf-avtcore-srtp-aes-gcm-06.

1. In section 5.2, Tag_Size_Flag is used for CCM mode input and it is
written that the tag size for GCM mode is determined by the algorithm
There is no difference between CCM and GCM from the point of view that the
ciphersuite can determine the tag length.
CCM needs tag length in the input formatting function while GCM does not.
But I think it does not imply that the inputs of GCM and CCM differ and it
is better to be consistent.

2. AES-CCM ciphersuites is defined for each tag length except but Section
I think it is better to add the following ciphersuites in Section 14.1 as
well as other parts of the draft.
- AEAD_AES_128_CCM_8
- AEAD_AES_256_CCM_8
- AEAD_AES_128_CCM_12
- AEAD_AES_256_CCM_12

3. Section 6, Section 11.1
 (2^24)-16 octets => (2^28)-16 octets

Regards, Woo-Hwan Kim