Maybe others will find this useful. I have collected some different functions to generate a short hash of a string in VBA. I don’t take credit for the code and all sources are referenced. CRC16 Function: =CRC16HASH(A1) with this Code hash is a 4 characters long HEX string 19 code lines 4 digits long hash … Read more
In C++03, boost::hash. In C++11, std::hash. std::hash<std::string>()(“foo”);
If you want an MD5 digest and have the Indy components installed, you can do this: uses SysUtils, IdGlobal, IdHash, IdHashMessageDigest; with TIdHashMessageDigest5.Create do try Result := TIdHash128.AsHex(HashValue(‘Hello, world’)); finally Free; end; Most popular algorithms are supported in the Delphi Cryptography Package: Haval MD4, MD5 RipeMD-128, RipeMD-160 SHA-1, SHA-256, SHA-384, SHA-512, Tiger Update DCPCrypt is … Read more
Thanks to John Montgomery I think I have found a solution, and I think it has less overhead than converting every number in possibly huge arrays to strings: I can create a byte-view of the arrays and use these to update the hash. And somehow this seems to give the same digest as directly updating … Read more
The problem being solved is that the previous hash algorithm in Lib/sets.py had horrendous performance on datasets that arise in a number of graph algorithms (where nodes are represented as frozensets): # Old-algorithm with bad performance def _compute_hash(self): result = 0 for elt in self: result ^= hash(elt) return result def __hash__(self): if self._hashcode is … Read more
A new salt should be randomly generated for each user and each time they change their password as a minimum. Don’t just rely on a site wide salt for example, as that defeats the point of using a salt in the first place. Using a unique salt for each user is so that if two … Read more
static UInt64 CalculateHash(string read) { UInt64 hashedValue = 3074457345618258791ul; for(int i=0; i<read.Length; i++) { hashedValue += read[i]; hashedValue *= 3074457345618258799ul; } return hashedValue; } This is a Knuth hash. You can also use Jenkins.
Unfortunately, this program has undefined behavior. C++11 ยง17.6.4.2.1: A program may add a template specialization for any standard library template to namespace std only if the declaration depends on a user-defined type and the specialization meets the standard library requirements for the original template and is not explicitly prohibited. hash<pair<int,int>> depends on primitive and standard … Read more
You need to hash about 2^64 values to get a single collision among them, on average, if you don’t try to deliberately create collisions. Hash collisions are very similar to the Birthday problem. If you look at two arbitrary values, the collision probability is only 2-128. The problem with md5 is that it’s relatively easy … Read more
No. The part of the URL starting with the # symbol is never sent to the server. The # symbol in an URL is to introduce the fragment identifier. This is used to link to a specific part of the page. If a browser loads /#some/url, it will effectively load /, and skip to the … Read more