- 
            
            as seen on Stack Overflow
            - Search for 'Stack Overflow' 
            
 To generate a valid pairwise master key for a WPA2 network a router uses the PBKDF2-HMAC-SHA1 algorithm.  I understand that the sha1 function is performed 4096 times to derive the PMK, however I have two questions about the process.
Excuse the pseudo code.
1) How is the input to the first instance…
            >>> More
 
- 
            
            as seen on Stack Overflow
            - Search for 'Stack Overflow' 
            
 Given two different strings S1 and S2 (S1 != S2) is it possible that:
SHA1(S1) == SHA1(S2)
is True?
If yes - with what probability?  Is there a upper bound on the length of a string, for which probably of getting duplicates is 0?
If not - why not?
Thanks
            >>> More
 
- 
            
            as seen on Stack Overflow
            - Search for 'Stack Overflow' 
            
 My problem is a bit hairy, and I may be asking the wrong questions, so please bear with me... 
I have a legacy MySQL database which stores the user passwords & salts for a membership system. Both of these values have been hashed using the Ruby framework - roughly like this:
  hashedsalt =
…
            >>> More
 
- 
            
            as seen on Stack Overflow
            - Search for 'Stack Overflow' 
            
 It is known that
1.    if   ( md5(a)   == md5(b)   )
2.    then ( md5(a.z) == md5(b.z) )
3.    but  ( md5(z.a) != md5(z.b) )
where the dots concatenate the strings.
What happens in the second row if we change all the md5 to sha1? So:
1.    if   ( sha1(c)   == sha1(d)   )
2.    then ( sha1(c.z)…
            >>> More
 
- 
            
            as seen on Stack Overflow
            - Search for 'Stack Overflow' 
            
 hi all,
i want to generate HMAC-SHA1 of NSString type variable. I see the post but this method give me error in CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
and
NSString *hash = [HMAC base64Encoding]; 
line.
Please suggest how can I generate the HMAC-SHA1 of any string…
            >>> More