L parameter for CCM #252

New issue

Closed

opened 2017-07-14 10:43:07 -05:00 by s09bQ5 · 2 comments

s09bQ5 commented

2017-07-14 10:43:07 -05:00

(Migrated from github.com)

If I understand RFC3610 correctly, L can be chosen freely as long as it allows the payload size to be encoded. But the current implementation of ccm_init uses the minimal value for L that can encode the payload size. So right now libtomcrypt can not be used to decrypt CCM messages that use an L that is bigger than necessary. In OpenSSL L defaults to 8 and can be changed to any allowed value.

karel-m commented

2017-07-14 13:46:35 -05:00

(Migrated from github.com)

If I understand our implementation correctly you can "choose" L indirectly by choosing nonce of proper length: L = 15 - length(nonce) where 7 <= length(nonce) <= 13

If I understand our implementation correctly you can "choose" `L` indirectly by choosing `nonce` of proper length: `L = 15 - length(nonce)` where `7 <= length(nonce) <= 13`

s09bQ5 commented

2017-07-14 14:05:50 -05:00

(Migrated from github.com)