Ruby

*

* You may want to have a look at OpenSSL::Digest as this implementation is more efficient, more up to date, and

* support more algorithms.

*

*

* A cryptographic hash function is a procedure that takes data and return a fixed bit string : the hash value,

* also known as _digest_. Hash functions are also called one-way functions : it is easy to compute a digest from

* a message, but it is infeasable to generate a message from a digest.

*

* ==Example

* require 'digest'

*

* # Compute a complete digest

* sha256 = Digest::SHA256.new

* digest = sha256.digest(message)

*

* # Compute digest by shunks

* sha256.reset

* sha256.update(message1)

* sha256 << message2 # << is an alias for update

* digest = sha256.digest

*

* ==Digest algorithms

* Different digest algorithms (or hash functions) are available :

* * SHA1 (see FIPS 180-2 <i>Secure Hash Standard</i>);

* * SHA2 family (SHA256, SHA384, SHA512, see FIPS 180-2 <i>Secure Hash Standard</i>) ;

* * HMAC (see FIPS PUB 198 <i>The Keyed-Hash Message Authentication Code (HMAC)</i>).

*