phc-discussions - Re: [PHC] pufferfish

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Message-ID: <5341694E.3080002@bindshell.nl>
Date: Sun, 06 Apr 2014 07:48:46 -0700
From: Jeremi Gosney <epixoip@...dshell.nl>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] pufferfish

On 4/6/2014 7:38 AM, Bill Cox wrote:
> On Sun, Apr 6, 2014 at 10:21 AM, Jeremi Gosney <epixoip@...dshell.nl> wrote:
>> On 4/6/2014 7:09 AM, Jeremi Gosney wrote:
>>> On 4/6/2014 7:03 AM, Bill Cox wrote:
>>>> Pufferfish has a minor bug in api.c.  I'm not 100% I got the fix
>>>> right, but I am 100% sure this is a bug.  On line 135, memmove is
>>>> calling strlen(hash) to determine how much data to copy.  It seems
>>>> like it should use strlen instead, assuming Pufferfish supports
>>>> variable out length.  Here's the diff after I made this change:
>>>>
>>>> diff --git a/Pufferfish/src/common/api.c b/Pufferfish/src/common/api.c
>>>> index 288937d..58daf4b 100644
>>>> --- a/Pufferfish/src/common/api.c
>>>> +++ b/Pufferfish/src/common/api.c
>>>> @@ -132,7 +132,7 @@ int PHS (void *out, size_t outlen, const void *in,
>>>> size_t inlen, const void *sal
>>>>                  return 1;
>>>>          }
>>>>
>>>> -        memmove (out, hash, strlen (hash));
>>>> +        memmove (out, hash, outlen);
>>>>          free (settings);
>>>>          free (hash);
>>>>
>>>> Bill
>>> No, this is incorrect. The `hash' variable in this context is not the
>>> raw hash value, it is the encoded hash plus the hash identifier and
>>> encoded salt string.
>>
>> If you want the raw hash value to e.g. run dieharder tests, then the
>> easiest way is to have PHS() call pfkdf() instead of pufferfish().  Or,
>> call pufferfish() with raw = true instead of raw = false, and change the
>> data type to unsigned char* instead of char*, then apply your
>> s/strlen/outlen/ patch.
> Got it.  I do want the raw version.  I'll do this later today.  This
> is the last one... all of the other 23 are running!
>
> Bill


This should work for what you want to do. But note that in this context
outlen is now specified in bits, not bytes.

--- a/src/common/api.c
+++ b/src/common/api.c
@@ -123,18 +123,10 @@ int PHS (void *out, size_t outlen, const void *in,
size_t inlen, const void *sal
 {
         /* required PHS api */

-        char *hash;
-        char *settings = pf_gensalt (salt, saltlen, t_cost, m_cost);
+        unsigned char *bytes = pfkdf (outlen, in, t_cost, m_cost);

-        if (! (hash = (char *) pufferfish (in, inlen, settings, outlen,
false)))
-        {
-                free (settings);
-                return 1;
-        }
-
-        memmove (out, hash, strlen (hash));
-        free (settings);
-        free (hash);
+        memmove (out, bytes, outlen);
+        free (bytes);

         return 0;
 }