module Cryptokit: sig .. end
The Cryptokit library provides a variety of cryptographic primitives
    that can be used to implement cryptographic protocols in
    security-sensitive applications.  The primitives provided include:
- Symmetric-key ciphers: AES, DES, Triple-DES, ARCfour,
      in ECB, CBC, CFB and OFB modes.
- Public-key cryptography: RSA encryption, Diffie-Hellman key agreement.
- Hash functions and MACs: SHA-1, SHA-256, SHA-3, RIPEMD-160, MD5,
      and MACs based on AES and DES.
- Random number generation.
- Encodings and compression: base 64, hexadecimal, Zlib compression.
    To use this library, link with 
      
ocamlc unix.cma nums.cma cryptokit.cma
    or
      
ocamlopt unix.cmxa nums.cmxa cryptokit.cmxa.
General-purpose abstract interfaces
class type transform = object .. end
A transform is an arbitrary mapping from sequences of characters
    to sequences of characters.
val transform_string : transform -> string -> string
transform_string t s runs the string s through the
      transform t and returns the transformed string.
      The transform t is wiped before returning, hence can
      no longer be used for further transformations.
val transform_channel : transform ->
       ?len:int -> Pervasives.in_channel -> Pervasives.out_channel -> unit
transform_channel t ic oc reads characters from input channel ic,
      runs them through the transform t, and writes the transformed
      data to the output channel oc.  If the optional len argument
      is provided, exactly len characters are read from ic and
      transformed; End_of_file is raised if ic does not contain
      at least len characters.  If len is not provided, ic is
      read all the way to end of file. 
      The transform t is wiped before returning, hence can
      no longer be used for further transformations.
val compose : transform -> transform -> transform
Compose two transforms, feeding the output of the first transform
      to the input of the second transform.
class type hash = object .. end
A hash is a function that maps arbitrarily-long character
    sequences to small, fixed-size strings.
val hash_string : hash -> string -> string
hash_string h s runs the string s through the hash function h
      and returns the hash value of s.  
      The hash h is wiped before returning, hence can
      no longer be used for further hash computations.
val hash_channel : hash -> ?len:int -> Pervasives.in_channel -> string
hash_channel h ic reads characters from the input channel ic,
      computes their hash value and returns it.
      If the optional len argument is provided, exactly len characters
      are read from ic and hashed; End_of_file is raised if ic
      does not contain at least len characters.
      If len is not provided, ic is read all the way to end of file.      
      The hash h is wiped before returning, hence can
      no longer be used for further hash computations.
Utilities: random numbers and padding schemes
module Random: sig .. end
The Random module provides random and pseudo-random number generators
    suitable for generating cryptographic keys, nonces, or challenges.
module Padding: sig .. end
The Padding module defines a generic interface
    for padding input data to an integral number of blocks,
    as well as two popular padding schemes.
Cryptographic primitives (simplified interface)
module Cipher: sig .. end
The Cipher module implements the AES, DES, Triple-DES, ARCfour
    and Blowfish symmetric ciphers.
module Hash: sig .. end
The Hash module implements unkeyed cryptographic hashes (SHA-1,
    SHA-256, RIPEMD-160 and MD5), also known as message digest functions.
module MAC: sig .. end
The MAC module implements message authentication codes, also
    known as keyed hash functions.
module RSA: sig .. end
The RSA module implements RSA public-key cryptography.
module DH: sig .. end
The DH module implements Diffie-Hellman key agreement.
Advanced, compositional interface to block ciphers 
       and stream ciphers
module Block: sig .. end
The Block module provides classes that implements
    popular block ciphers, chaining modes, and wrapping of a block cipher
    as a general transform or as a hash function.
module Stream: sig .. end
The Stream module provides classes that implement
    the ARCfour stream cipher, and the wrapping of a stream cipher
    as a general transform.
Encoding and compression of data
module Base64: sig .. end
The Base64 module supports the encoding and decoding of
    binary data in base 64 format, using only alphanumeric
    characters that can safely be transmitted over e-mail or
    in URLs.
module Hexa: sig .. end
The Hexa module supports the encoding and decoding of
    binary data as hexadecimal strings.
module Zlib: sig .. end
The Zlib module supports the compression and decompression
    of data, using the zlib library.
Error reporting
type 
| | | Wrong_key_size | 
| | | Wrong_IV_size | 
| | | Wrong_data_length | 
| | | Bad_padding | 
| | | Output_buffer_overflow | 
| | | Incompatible_block_size | 
| | | Number_too_long | 
| | | Seed_too_short | 
| | | Message_too_long | 
| | | Bad_encoding | 
| | | Compression_error of string * string | 
| | | No_entropy_source | 
| | | Entropy_source_closed | 
| | | Compression_not_supported | 
Error codes for this library.
exception Error of error
Exception raised by functions in this library
      to report error conditions.
Miscellaneous utilities
val wipe_string : string -> unit
wipe_string s overwrites s with zeroes.  Can be used
        to reduce the memory lifetime of sensitive data.
val xor_string : string -> int -> string -> int -> int -> unit
xor_string src spos dst dpos len performs the xor (exclusive or)
        of characters spos, ..., spos + len - 1 of src
        with characters dpos, ..., dpos + len - 1 of dst,
        storing the result in dst starting at position dpos.
val mod_power : string -> string -> string -> string
mod_power a b c computes a^b mod c, where the
        strings a, b, c and the result string are viewed as
        arbitrary-precision integers in big-endian format.
        Requires a < c.
val mod_mult : string -> string -> string -> string
mod_mult a b c computes a*b mod c, where the
        strings a, b, c and the result string are viewed as
        arbitrary-precision integers in big-endian format.