Of all bit-operations XOR has the best bit shuffling properties. This truth-table explains why: A B AND 0 0 0 0 1 0 1 0 0 1 1 1 A B OR 0 0 0 0 1 1 1 0 1 1 1 1 A B XOR 0 0 0 0 1 1 1 0 … Read more
Could this be a typo? (two Ps in ppasscode, intended?) $_POST[‘ppasscode’]; I would make sure and do: print_r($_POST); and make sure the data is accurate there, and then echo out what it should look like: echo hash(‘sha256’, $_POST[‘ppasscode’]); Compare this output to what you have in the database (manually). By doing this you’re exploring your … Read more
None of the answers provided seemed particularly useful, given the question. I had the same problem, needing a simple, reversible hash for not-security purposes, and decided to go with bit relocation. It’s simple, it’s fast, and it doesn’t require knowing anything about boolean maths or crypo algorithms or anything else that requires actual thinking. The … Read more
There are some legitimate symbols that cannot be used with the new syntax. I cannot find a reference, but it appears that a symbol name matching /^[a-zA-Z_][a-zA-Z_0-9]*[!?]?$/ is allowed with the new syntax. The last character may be the special character “!” or “?”. For any symbol that does not meet these restrictions, you have … Read more
In your case, breaking the hash algorithm is equivalent to finding a collision in the hash algorithm. That means you don’t need to find the password itself (which would be a preimage attack), you just need to find an output of the hash function that is equal to the hash of a valid password (thus … Read more
I believe what you’re looking for is called a Locality Sensitive Hash. Whereas most hash algorithms are designed such that small variations in input cause large changes in output, these hashes attempt the opposite: small changes in input generate proportionally small changes in output. As others have mentioned, there are inherent issues with forcing a … Read more
To elaborate a bit more about why the short hash is useful, and why you often don’t need the long hash, it has to do with how Git stores things. c26cf8af130955c5c67cfea96f9532680b963628 will be stored in one of two places. It could be in the file .git/objects/c2/6cf8af130955c5c67cfea96f9532680b963628. Note that the first two characters, c2, make up … Read more
import hmac import hashlib import base64 dig = hmac.new(b’1234567890′, msg=your_bytes_string, digestmod=hashlib.sha256).digest() base64.b64encode(dig).decode() # py3k-mode ‘Nace+U3Az4OhN7tISqgs1vdLBHBEijWcBeCqL5xN9xg=’
Under the appropriate assumptions on the hash function being used, we can say that hash table lookups take expected O(1) time (assuming you’re using a standard hashing scheme like linear probing or chained hashing). This means that on average, the amount of work that a hash table does to perform a lookup is at most … Read more
On your PHP side, use single-quotes around the key so that the $ character is not treated as a variable reference. i.e., hash_hmac(“sha1”, “helloworld”, ‘PRIE7$oG2uS-Yf17kEnUEpi5hvW/#AFo’) Otherwise, the key you really get is PRIE7-Yf17kEnUEpi5hvW/#AFo (assuming the variable $oG2uS is not defined).