Re: CRYPTO_MAX_MAC_LEN too short?
"Steven M. Bellovin" <[email protected]>
| Newsgroups | gmane.os.netbsd.devel.crypto |
|---|---|
| Message-ID | <[email protected]> |
In message <[email protected]>, "Nathan J. Willia ms" writes: > >In opencrypto/cryptodev.h, CRYPTO_MAX_MAC_LEN is defined as 20. This >value is used in cryptodev.c to set the size of the tmp_mac[] array, >which is passed down to into crypto engines for them to deposit the >computed MAC or hash. However, we've got SHA-2 (256 bits), SHA-2-384, >and SHA-2-512, all of which produce more than 20 bytes of result, so >using those hashes runs some risk of stomping on the other data >structures following it. > >Any reason not to bump up CRYPTO_MAX_MAC_LEN to 64? > It certainly wouldn't hurt, but is the field for a hash function output or for an HMAC output? The latter, even for SHA-512, is unlikely to be longer than 20 bytes. --Prof. Steven M. Bellovin, http://www.cs.columbia.edu/~smb