[openssl.org #3095] Incorrect result in HMAC functions when key is null

2013-07-26 Thread Jake Thomas Petroules via RT 
Hello,

I've discovered a bug in OpenSSL HMAC handling -- when calling the HMAC() 
(http://www.openssl.org/docs/crypto/hmac.html) function, an incorrect result 
will be given if the `key` parameter is a NULL pointer, even when `key_len` is 
zero. Much easier to notice when you're not using null terminated 
strings/buffers. I would expect that the value of `key` would have no effect if 
`key_len` is 0 (CommonCrypto handles this fine). I have attached an example 
program demonstrating the problem.

Please post the eventual bug tracker link on the mailing list if possible.

Thanks,
-- 
Jake Petroules
Chief Technology Officer
Petroules Corporation · www.petroules.com
Email: jake.petrou...@petroules.com


Hello,I've discovered a bug in OpenSSL HMAC handling -- when calling the HMAC()(http://www.openssl.org/docs/crypto/hmac.html) function, an incorrect result will be given if the `key` parameter is a NULL pointer, even when `key_len` is zero. Much easier to notice when you're not using null terminated strings/buffers. I would expect that the value of `key` would have no effect if `key_len` is 0 (CommonCrypto handles this fine). I have attached an example program demonstrating the problem.Please post the eventual bug tracker link on the mailing list if possible.Thanks,
--Jake PetroulesChief Technology OfficerPetroules Corporation ·www.petroules.comEmail:jake.petrou...@petroules.com

openssl-hmac-bug.c
Description: Binary data

Re: [openssl.org #3095] Incorrect result in HMAC functions when key is null

2013-07-26 Thread Jake Thomas Petroules via RT 
After reviewing the documentation I see this behavior mentioned - easy to miss.
However I'd argue that this behavior is wrong, given that there is no context to
potentially re-use with the single shot function.

Wouldn't it make more sense to simply treat a NULL pointer to key the same as
passing a valid pointer, when key_len is 0, for the single-shot function?
-- 
Jake Petroules
Chief Technology Officer
Petroules Corporation · www.petroules.com
Email: jake.petrou...@petroules.com

On Jul 26, 2013, at 8:46 AM, Stephen Henson via RT r...@openssl.org wrote:

 On Fri Jul 26 09:26:23 2013, jake.petrou...@petroules.com wrote:
 Hello,
 
 I've discovered a bug in OpenSSL HMAC handling -- when calling the
 HMAC() (http://www.openssl.org/docs/crypto/hmac.html) function, an
 incorrect result will be given if the `key` parameter is a NULL
 pointer, even when `key_len` is zero. Much easier to notice when
 you're not using null terminated strings/buffers. I would expect
 that the value of `key` would have no effect if `key_len` is 0
 (CommonCrypto handles this fine). I have attached an example
 program demonstrating the problem.
 
 
 Passing NULL as the key has a special meaning to the OpenSSL APIs: it reuses
 the existing HMAC key for the context. If there is no HMAC key previously set
 the result is undefined. If you really want to use a zero length key set
 key_len to zero and key to non-NULL.
 
 Steve.
 --
 Dr Stephen N. Henson. OpenSSL project core developer.
 Commercial tech support now available see: http://www.openssl.org


__
OpenSSL Project http://www.openssl.org
Development Mailing List   openssl-dev@openssl.org
Automated List Manager   majord...@openssl.org