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Module Cryptokit


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: 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 and ARCfour 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 error =
| Wrong_key_size (*The key is too long or too short for the given cipher.*)
| Wrong_IV_size (*The initialization vector does not have the same size as the block size.*)
| Wrong_data_length (*The total length of the input data for a transform is not an integral multiple of the input block size.*)
| Bad_padding (*Incorrect padding bytes were found after decryption.*)
| Output_buffer_overflow (*The output buffer for a transform exceeds the maximal length of a Caml string.*)
| Incompatible_block_size (*A combination of two block ciphers was attempted whereby the ciphers have different block sizes, while they must have the same.*)
| Number_too_long (*Denotes an internal error in RSA key generation or encryption.*)
| Seed_too_short (*The seed given to a pseudo random number generator is too short.*)
| Message_too_long (*The message passed to RSA encryption or decryption is greater than the modulus of the RSA key*)
| Bad_encoding (*Illegal characters were found in an encoding of binary data such as base 64 or hexadecimal.*)
| Compression_error of string * string (*Error during compression or decompression.*)
| No_entropy_source (*No entropy source (OS, /dev/random or EGD) was found for Cryptokit.Random.secure_rng.*)
| Entropy_source_closed (*End of file on a device or EGD entropy source.*)
| Compression_not_supported (*The data compression functions are not available.*)
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.