sha-256

online hash generator

This online hash calculator calculates the SHA-256 hash for your input. Type or paste your input into the upper window, click the calculate button, and the SHA256 hash of your input will be displayed. You can copy the hash value to to the clipboard for use elsewhere.

A hash is a fixed-length digital fingerprint that is unique for every input.
  hash(message1) ≠ hash(message2)

Store a hash as proof of knowledge without storing the object itself. Don’t store passwords, credit card numbers, or other sensitive data. Store the hash instead. Alice and Bob can confirm a shared secret in a crowded elevator by saying the hash out loud. Eve gains no knowledge about their secret even when the shout the hash in a crowd. (Rainbow tables, databases of pre-computed hashes, must be taken into consideration which is why I suggest a key of 14 or more characters.)

It’s very, very hard to find two inputs that generate the same hash value.
  hash(message1) = hash(message2)

Collisions, when two or more inputs share the same hash value, are extremely rare. Alice and Bob share knowledge of a shared secret by agreeing on its hash value. Overhearing this is Mallory but he can’t spoof their secret to others because he can’t find another message that generates the same hash value. And everyone in the elevator already heard Alice and Bob agree what that hash value is.

Knowing a hash value doesn’t give you any clue about what the original input value was. There’s no leakage with a good hash algorithm. Strong hashes are one-way functions so knowing the output (the hash) doesn’s help you reconstruct the input (the originalm message).

Hashes are used for message authentication, like HMAC (Hash-based Message Authenication Codes) because they’ar unique for different inputs and because you can’t substitute message1 with message2 and get the same hash.

test vectors
For the input The quick brown fox jumps over the lazy dog the SHA-256 value is: d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592
For the input: The 728 Club the SHA-256 hash is 75191ea0a07d971b5551c963e684a1bdea84b4e364c7b501979fd06e22ba6ac1 So there.

The hash code used is from Google Code.