From 5dc9baf75b3170fe9db9bb4fd78947c26f11fb51 Mon Sep 17 00:00:00 2001 From: Werner Koch Date: Sat, 30 Aug 2003 10:05:23 +0000 Subject: (Working with hash algorithms): Clarified that HMAC does not work with all algorithms. --- TODO | 3 +++ doc/ChangeLog | 5 +++++ doc/gcrypt.texi | 10 ++++++---- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/TODO b/TODO index 6f7903dd..b1963354 100644 --- a/TODO +++ b/TODO @@ -25,3 +25,6 @@ the asymmetric ciphers could be changed for convenient interaction with the ac interface (i.e. by using ac's `data sets') and the pk interface could be changed to be a wrapper for the ac interface. + +* HMAC won't work with sha-512 due to the different block size. OTOH, + I can imagine no cryptographic reason to use it. diff --git a/doc/ChangeLog b/doc/ChangeLog index 94badb6f..2e8bb93f 100644 --- a/doc/ChangeLog +++ b/doc/ChangeLog @@ -1,3 +1,8 @@ +2003-08-30 Werner Koch + + * gcrypt.texi (Working with hash algorithms): Clarified that HMAC + does not work with all algorithms. + 2003-07-30 Moritz Schulte * gcrypt.texi (Available asymmetric algorithms): Mention diff --git a/doc/gcrypt.texi b/doc/gcrypt.texi index 8a869d5c..e3f103c9 100644 --- a/doc/gcrypt.texi +++ b/doc/gcrypt.texi @@ -1689,10 +1689,12 @@ Allocate all buffers and the resulting digest in "secure memory". Use this is the hashed data is highly confidential. @item GCRY_MD_FLAG_HMAC -Turn the algorithm into a HMAC message authentication algorithm. Note -that the function @code{gcry_md_setkey} must be used set the MAC key. -If you want CBC message authentication codes based on a cipher, see -@xref{Working with cipher handles}. +Turn the algorithm into a HMAC message authentication algorithm. This +does only work if just one algorithm is enabled for the handle and +SHA-384 and SHA512 is not used. Note that the function +@code{gcry_md_setkey} must be used set the MAC key. If you want CBC +message authentication codes based on a cipher, see @xref{Working with +cipher handles}. @end table @c begin table of hash flags -- cgit v1.2.1