Tool to decrypt / encrypt with hash functions (MD5, SHA1, SHA256, bcrypt, etc.) automatically. The hashing of a given data creates a fingerprint that makes it possible to identify the initial data with a high probability (very useful in computer science and cryptography).

Hash Function - dCode

Tag(s) : Modern Cryptography, Informatics

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The **hash** functions use computer data (in binary format) and apply nonlinear and non-reversible functions with a strong avalanche effect (the result is very different even if the input data is very similar). The fingerprint is usually returned as hexadecimal characters.

__Example:__ `dCode` has for **hash** MD5 `e9837d47b610ee29399831f917791a44`

__Example:__ `dCode` has for **hash** SHA1 `15fc6eed5ed024bfb86c4130f998dde437f528ee`

__Example:__ `dCode` has for **hash** SHA256 `254cd63ece8595b5c503783d596803f1552e0733d02fe4080b217eadb17711dd`

The principle of hashing is not to be reversible, there is no decryption algorithm, that's why it is used for storing passwords: it is stored encrypted and not unhashable.

__Example:__ `123+456=579`, from `579` how to find `123` and `456`? This is not possible except by trying all possible combinations.

The **hash** functions apply millions of non-reversible operations so that the input data can not be retrieved.

**Hash** functions are created to not be decrypable, their algorithms are public. The only way to decrypt a **hash** is to know the input data.

Theoretically, a brute-force mode is possible by testing all the binary strings, but a short message of 6 bytes already represents 281,000 billion combinations. Even with fast processors capable of performing millions of **hash** calculations per second, several days, months or years of calculations are therefore necessary to try all the possibilities in order to find a single **hash**.

However, users generally always use the same passwords and some characters more than others, so it is possible to store the most likely binary strings and their respective hashes in a very large dictionary. These dictionaries are called rainbow tables. These tables make it possible to test all the words of a given dictionary to check if their fingerprint corresponds to a given one.

__Example:__ dCode uses its word and password databases with millions of pre-calculated hashes.

If the word is not in the dictionary, then there will be no result.

A **hash** can take many forms, but the most common are hexadecimal strings: 32 characters `0123456789abcdef` for the MD5, 40 for the SHA-1, 64 for the SHA-256, etc.

The encoding system based on bcrypt uses the symbol `$` followed by a number indicating the algorithm used and its possible parameters.

The rainbow tables (gigantic databases of **hash** and password matches) are growing day by day and accumulating passwords stolen from various sites, and taking advantage of the computational performance of super calculators, allow today to decipher short passwords in minutes / hours.

In order to counter this technique, it is recommended to add `salt` (some characters in prefix or suffix) to the password/message. In this way, the precalculated tables must again be calculated to account for the salt that systematically modifies all the fingerprints, the salting step. Passwords are *salted*.

Cost is the measure of the resources needed to calculate a **hash**. In order to complicate the task of creating the rainbow tables, it is possible to complicate some hashes so that the calculations take several milliseconds or seconds, which makes the duration necessary for the attacks too great to be applicable.

bcrypt is a library of cryptographic functions that applies recursion rules to **hash** functions. Natively, the notions of salt and cost are applicable.

dCode retains ownership of the online "Hash Function" tool source code. Except explicit open source licence (indicated CC / Creative Commons / free), any "Hash Function" algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any "Hash Function" function (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and no data download, script, copy-paste, or API access for "Hash Function" will be for free, same for offline use on PC, tablet, iPhone or Android ! dCode is free and online.

Please, check our dCode Discord community for help requests!

NB: for encrypted messages, test our automatic cipher identifier!

hash,message,md5,sha1,sha256,bcrypt,password,salt,salting,salted

Source : https://www.dcode.fr/hash-function

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