Message digest.
This module provides functions to compute 'digests', also known as 'hashes', of arbitrary-length strings or files. The supported hashing algorithms are BLAKE2 and MD5.
The functions in this section use the MD5 hash function to produce 128-bit digests (16 bytes). MD5 is not cryptographically secure. Hence, these functions should not be used for security-sensitive applications. The BLAKE2 functions below are cryptographically secure.
The comparison function for 16-byte digests, with the same specification as Stdlib.compare and the implementation shared with String.compare. Along with the type t, this function compare allows the module Digest to be passed as argument to the functors Set.Make and Map.Make.
val string : string -> tReturn the digest of the given string.
val bytes : bytes -> tReturn the digest of the given byte sequence.
val substring : string -> int -> int -> tDigest.substring s ofs len returns the digest of the substring of s starting at index ofs and containing len characters.
val subbytes : bytes -> int -> int -> tDigest.subbytes s ofs len returns the digest of the subsequence of s starting at index ofs and containing len bytes.
val channel : in_channel -> int -> tIf len is nonnegative, Digest.channel ic len reads len characters from channel ic and returns their digest, or raises End_of_file if end-of-file is reached before len characters are read. If len is negative, Digest.channel ic len reads all characters from ic until end-of-file is reached and return their digest.
val file : string -> tReturn the digest of the file whose name is given.
val output : out_channel -> t -> unitWrite a digest on the given output channel.
val input : in_channel -> tRead a digest from the given input channel.
val to_hex : t -> stringReturn the printable hexadecimal representation of the given digest.
val of_hex : string -> tConvert a hexadecimal representation back into the corresponding digest.
val from_hex : string -> tSame function as Digest.of_hex.
module type S = sig ... endThe signature for a hash function that produces digests of length hash_length from character strings, byte arrays, and files.
BLAKE128 is the BLAKE2b hash function producing 128-bit (16-byte) digests. It is cryptographically secure. However, the small size of the digests enables brute-force attacks in 2{^64} attempts.
BLAKE256 is the BLAKE2b hash function producing 256-bit (32-byte) digests. It is cryptographically secure, and the digests are large enough to thwart brute-force attacks.
BLAKE512 is the BLAKE2b hash function producing 512-bit (64-byte) digests. It is cryptographically secure, and the digests are large enough to thwart brute-force attacks.