In the test program, you are feeding a fixed ccm_tag to decryption process. This will not work for CCM, as tag length itself will also be an input for tag generation. Change in tag length, will change the tag produced. I modified the decryption api(aes_ccm_decrypt) to take the tag generated by encryption api(aes_ccm_encrypt). It works fine.
Note: Tag length will internally be embedded within the IV(nonce). On Wed, Jun 18, 2014 at 8:12 PM, Michel <msa...@paybox.com> wrote: > I tried all of 2, 4, 6, 8, 10, 12, 14, 16 values, and always got a > "Plaintext not available: tag verify failed". > Even when tag length of decryption was equal to tag length of encryption. > :-( > It just works for : tag length of decryption = tag length of encryption = > 16. > > Thanks again for your help. > > Le 18/06/2014 16:14, Thulasi Goriparthi a écrit : > > Truncate-able tags gave a way to truncated hmac extension. >> Haven't gone through CCM RFC 3610 completely. >> >> I can see the restriction of possible M values(Tag lengths) to 2, 4, 6, >> 8, 10, 12, 14, 16. Can you try reducing the tag size accordingly and see if >> it succeeds. >> >> > > ______________________________________________________________________ > OpenSSL Project http://www.openssl.org > User Support Mailing List openssl-users@openssl.org > Automated List Manager majord...@openssl.org >
