Module Core_kernel.Md5

This module implements the MD5 message-digest algorithm as described IETF RFC 1321. t is the result type and val digest_string : string -> t is the implementation of the algorithm itself.

This is currently a thin wrapper over the Digest module in INRIA's standard library.

module Stable : sig ... end
module As_binary_string : sig ... end

Both bin_io and sexp serializations produce a binary 16-character string.

type t = Stable.V1.t

Intended to represent a 16-byte string that is the output of MD5 algorithm.

Note that any 16-byte string can be converted to this type, so a value of type t is not an evidence of someone having found an input corresponding to this output.

include Bin_prot.Binable.S with type t := t
include Bin_prot.Binable.S_only_functions with type t := t
val bin_size_t : t Bin_prot.Size.sizer
val bin_write_t : t Bin_prot.Write.writer
val bin_read_t : t Bin_prot.Read.reader
val __bin_read_t__ : (int -> t) Bin_prot.Read.reader

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

val bin_shape_t : Bin_prot.Shape.t
val bin_writer_t : t Bin_prot.Type_class.writer
val bin_reader_t : t Bin_prot.Type_class.reader
include Ppx_sexp_conv_lib.Sexpable.S with type t := t
val t_of_sexp : Sexplib0.Sexp.t -> t
val sexp_of_t : t -> Sexplib0.Sexp.t
val hash_fold_t : Base.Hash.state -> t -> Base.Hash.state
val hash : t -> Base.Hash.hash_value
include Interfaces.Comparable with type t := t
include Base.Comparable.S with type t := t
include Base.Comparisons.S with type t := t
include Base.Comparisons.Infix with type t := t
val (>=) : t -> t -> bool
val (<=) : t -> t -> bool
val (=) : t -> t -> bool
val (>) : t -> t -> bool
val (<) : t -> t -> bool
val (<>) : t -> t -> bool
val equal : t -> t -> bool
val min : t -> t -> t
val max : t -> t -> t
val ascending : t -> t -> int

ascending is identical to compare. descending x y = ascending y x. These are intended to be mnemonic when used like List.sort ~compare:ascending and List.sort ~cmp:descending, since they cause the list to be sorted in ascending or descending order, respectively.

val descending : t -> t -> int
val between : t -> low:t -> high:t -> bool

between t ~low ~high means low <= t <= high

val clamp_exn : t -> min:t -> max:t -> t

clamp_exn t ~min ~max returns t', the closest value to t such that between t' ~low:min ~high:max is true.

Raises if not (min <= max).

val clamp : t -> min:t -> max:t -> t Base.Or_error.t
include Base.Comparator.S with type t := t
type comparator_witness
val validate_lbound : min:t Base.Maybe_bound.t -> t Base.Validate.check
val validate_ubound : max:t Base.Maybe_bound.t -> t Base.Validate.check
val validate_bound : min:t Base.Maybe_bound.t -> max:t Base.Maybe_bound.t -> t Base.Validate.check
module Map : Map.S with type Key.t = t with type Key.comparator_witness = comparator_witness
module Set : Set.S with type Elt.t = t with type Elt.comparator_witness = comparator_witness
include Interfaces.Binable with type t := t
val bin_size_t : t Bin_prot.Size.sizer
val bin_write_t : t Bin_prot.Write.writer
val bin_read_t : t Bin_prot.Read.reader
val __bin_read_t__ : (int -> t) Bin_prot.Read.reader

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

val bin_shape_t : Bin_prot.Shape.t
val bin_writer_t : t Bin_prot.Type_class.writer
val bin_reader_t : t Bin_prot.Type_class.reader
include Interfaces.Hashable with type t := t
include Hashable.Common with type t := t
val compare : t -> t -> Base.Int.t
val hash_fold_t : Base.Hash.state -> t -> Base.Hash.state
val hash : t -> Base.Hash.hash_value
val hashable : t Hashtbl.Hashable.t
module Table : Hashtbl.S with type key = t
module Hash_set : Hash_set.S with type elt = t
module Hash_queue : Hash_queue.S with type key = t
val digest_num_bytes : int

digest_num_bytes = 16 is the size of the digest in bytes.

val to_binary : t -> string

Binary representations are 16 bytes long, and not human readable.

val of_binary_exn : string -> t
val to_hex : t -> string

to_hex prints each byte of t as a big-endian sequence of 2 hex digits (e.g. byte 31 is written as "1f") and then concatenates them. For example,

Md5.to_hex (Md5.digest_string "a") =
Md5.to_hex (
  Md5.of_binary_exn
    "\x0c\xc1\x75\xb9\xc0\xf1\xb6\xa8\x31\xc3\x99\xe2\x69\x77\x26\x61") =
"0cc175b9c0f1b6a831c399e269772661"
val of_hex_exn : string -> t

The inverse of to_hex. This function ignores case. It will raise an exception if the string is not a 32-byte-long string of hex digits.

val digest_string : string -> t
val digest_bytes : bytes -> t
val digest_subbytes : bytes -> pos:int -> len:int -> t

digest_subbytes m ~pos ~len computes Md5 digest of the substring of m of length len starting at pos.

val digest_file_blocking : string -> t

digest_file_blocking filename reads the contents of file filename and computes its digest.

val digest_channel_blocking_without_releasing_runtime_lock : in_channel -> len:int -> t

Reads len bytes from the given channel and computes md5 digest of that.

WARNING: This function does digest computation with OCaml global lock held, so it can be slow and make the other threads starve. See digest_file_blocking.

val input_blocking : in_channel -> t

Reads an Md5 digest from the given channel (in a format written by output_blocking)

val output_blocking : t -> out_channel -> unit

Writes the Md5 digest to the given channel.

val string : string -> t
val bytes : bytes -> t
val subbytes : bytes -> int -> int -> t
val from_hex : string -> t
val file : string -> t
val channel : in_channel -> int -> t
val output : out_channel -> t -> unit
val input : in_channel -> t
val digest_bin_prot : 'a Bin_prot.Type_class.writer -> 'a -> t

digest_bin_prot w x digests the serialization of x by w. It is a cheap way (in dev time) to compute the digest of an ocaml value, for a fixed and deterministic serialization function. It is currently implemented inefficiently and allocates large strings.

For a more efficient and resource-aware version, use Bigbuffer.add_bin_prot and Bigbuffer_blocking.md5.

val digest_bigstring : Bigstring.t -> t
val digest_subbigstring : Bigstring.t -> pos:int -> len:int -> t