/** \mainpage Documentation for AVR-Crypto-Lib
 \section Algorithms Available algorithms
 \subsection Stream-ciphers Stream ciphers
  A stream cipher generates a keystream which is normaly XORed with the
  plaintext to produce the the ciphertext. Stream ciphers therfore have a 
  state which is automaticaly updated to produce the next element of the 
  keystream. Most Streamciphers produce a fixed length of keytream per 
  iteration which may be a byte, a bit or any other data unit.
  
  Implemented stream ciphers: 
   - A5/1 (A5_1.h)
   - ARCFOUR (RC4 compatible) (arcfour.h)
   - Grain (grain.h)
   - Trivium (trivium.h)
   
 \subsection Block-ciphers Block ciphers 
  Block cipher encrypt/decrypt fixed length blocks (mostly 64 bits or 128 bits)
  with a key. Most block ciphers iterate a round function which uses a so-called
  round key. The round keys are generated on the fly or with a special init
  function (this is cipher specific). Round keys are stored in a context which
  is not modifyed by the encryption or decryption function. Also the same 
  context can be used for encryption and decryption and depends only on the key
  and its length.
  
  Implemented block ciphers:
   - Camellia (camellia.h)
   - CAST5 (a.k.a CAST-128) (cast5.h)
   - CAST6 (a.k.a CAST-256) (cast6.h)
   - DES & Tripple-DES (EDE) (des.h)
   - Noekeon (noekeon.h)
   - RC5 (rc5.h)
   - RC6 (rc6.h)
   - SEED (seed.h)
   - Serpent (serpent.h)
   - Shabea (shabea.h)
   - SHACAL-1 (encryption only) (shacal1_enc.h)
   - SHACAL-2 (encryption only) (shacal2_enc.h)
   - Skipjack (skipjack.h)
   - XTEA (xtea.h)
   
 \subsection Hashes Hashes
  A Hash function produces a fixed length output (called hash value or message
  digest) from a variable length message input. Most hash algorithms have a 
  state which is updated by the hash core function from a block of fixed size 
  from the message. A "lastBlock" function is used to add the last block which
  is not required to have the fixed length. An addition function is then used
  to transform the state into the final hash value.
  
  Implemented hash functions:
   - MD5 (md5.h)
   - SHA-1 (sha1.h)
   - SHA-256 (sha256.h)
   - Blake
   - Blue Midnight Wish
   - Grøstl
   - Keccak
   - Shabal
   - Skein
   - Twister
   
 \subsection MACs Message-Authentification-Codes (MACs)
  Message-Authentification-Codes work like hash function but take an additional
  key. The produced output is also called MAC and is highly dependant on the
  key. They can be thought of symmetric signatures.
  
  Implemented MAC functions:
   - HMAC-SHA-1 (hmac-sha1.h)
   - HMAC-SHA-256 (hmac-sha256.h)
   

 \subsection PRNGs Pseudo-Random-Number-Generators (PRNGs)
  PRNGs produce pseudo random output determinated by the input. They aim to 
  produce an arbitrary length of good cryptographically secure random if the
  input has enough entropy. PRNGs differ in the way they accept input. Some
  are seeded only once, other (like the implemented) maintain an entropy pool
  to which input can be added at virtually any time.
  
  Implemented PRNGs:
   - Entropium (entropium.h)
   
*/