The difference is that: PBKDF2 by design is slow; SHA256 is a good hash function; it is not slow, by design; So if someone were to try a lot of different possible passphrases, say the whole dictionary, then each word with a digit appended, then each word with a different capitalisation, then two dictionary words, etc. then this process would be much slower with PBKDF2.

Apr 29, 2013 · As far as PBKDF2 iterations in specific, one popular GPU based cracking program can handle with a kitted out modern desktop + 8 GPU's at 1 million tries a second against WPA2. As WPA2 is essentially PBKDF2(HMAC−SHA1, passphrase, ssid, 4096, 256), that tells us that one machine can test somewhat over 4 billion HMAC-SHA1 PBKDF2 iterations per ...

My planned PBKDF2 salt is: a per-user random salt (stored in the clear with each user record) XOR'ed with a global salt. The objective is to increase the cost of brute forcing passwords and to avoid revealing pairs of users with identical passwords.

Sep 23, 2016 · From the documentation on pbkdf2_sha256: salt (bytes) Optional salt bytes. If specified, the length must be between 0-1024 bytes. If not specified, a 16 byte salt will be autogenerated (this is recommended). salt_size (int) – Optional number of bytes to use when autogenerating new salts. Defaults to 16 bytes, but can be any value between 0 ...

Jan 13, 2013 · PBKDF2 is a key derivation function: it produces an output of configurable size. For password hashing, you want the size to be large enough to deter generic preimage attacks (i.e. trying random passwords until a match is found), so this would need, say, at …

Jun 7, 2015 · Attackers are going to use something like oclHashcat, which on a single PC with 8x AMD R9 290Xstock core clock is able to attempt 3.4E12 (2^41) guesses every 30 days against PBKDF2-HMAC-SHA-1(SSID as salt, password, 32 bytes output length, 4096 iterations, a.k.a. WPA/WPA2), which is more or less equivalent to PBKDF2-HMAC-SHA-1(salt,pw,20 bytes ...

Aug 9, 2016 · See this answer for some discussion of bcrypt vs PBKDF2. Though SHA-256-crypt is not PBKDF2, it is similar enough in its performance behaviour on GPU, so the same conclusions apply. Case for SHA-512 is a bit less clear because existing GPU are much better at using 32-bit integers than 64-bit, and SHA-512 uses mostly 64-bit operations.

Mar 26, 2014 · There is no "quick check" mechanism that is secure, by definition. The whole point of using PBKDF2 or related techniques is to make password checking slow, to foil password cracking programs. If you added a quick check system, password crackers would be able to guess passwords in bulk very quickly.

Jun 4, 2014 · 3. PBKDF2 length: See this other discussion about key lengths. The parameter is again the hashing function used, in your case SHA-1, so 20 bytes is the correct value. Since PBKDF2's Standard recommends salts of at least 64 bits, it's a waste to generate keys smaller than your input, so use at least 8 bytes. Do not use output length of greater ...

Apr 14, 2004 · PBKDF2. You were really close actually. The link you have given shows you how you can call the Rfc2898DeriveBytes function to get PBKDF2 hash results. However, you were thrown off by the fact that the example was using the derived key for encryption purposes (the original motivation for PBKDF1 and 2 was to create "key" derivation functions ...