.TH "Digest" 3o 2020-10-30 OCamldoc "OCaml library"
.SH NAME
Digest \- MD5 message digest.
.SH Module
Module   Digest
.SH Documentation
.sp
Module
.BI "Digest"
 : 
.B sig end

.sp
MD5 message digest\&.
.sp
This module provides functions to compute 128\-bit \&'digests\&' of
arbitrary\-length strings or files\&. The digests are of cryptographic
quality: it is very hard, given a digest, to forge a string having
that digest\&. The algorithm used is MD5\&. This module should not be
used for secure and sensitive cryptographic applications\&. For these
kind of applications more recent and stronger cryptographic
primitives should be used instead\&.

.sp

.sp
.sp
.I type t 
= 
.B string

.sp
The type of digests: 16\-character strings\&.

.sp

.I val compare 
: 
.B t -> t -> int
.sp
The comparison function for 16\-character digest, with the same
specification as 
.ft B
compare
.ft R
and the implementation
shared with 
.ft B
String\&.compare
.ft R
\&. Along with the type 
.ft B
t
.ft R
, this
function 
.ft B
compare
.ft R
allows the module 
.ft B
Digest
.ft R
to be passed as
argument to the functors 
.ft B
Set\&.Make
.ft R
and 
.ft B
Map\&.Make
.ft R
\&.

.sp
.B "Since"
4.00.0

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.I val equal 
: 
.B t -> t -> bool
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The equal function for 16\-character digest\&.

.sp
.B "Since"
4.03.0

.sp

.I val string 
: 
.B string -> t
.sp
Return the digest of the given string\&.

.sp

.I val bytes 
: 
.B bytes -> t
.sp
Return the digest of the given byte sequence\&.

.sp
.B "Since"
4.02.0

.sp

.I val substring 
: 
.B string -> int -> int -> t
.sp

.ft B
Digest\&.substring s ofs len
.ft R
returns the digest of the substring
of 
.ft B
s
.ft R
starting at index 
.ft B
ofs
.ft R
and containing 
.ft B
len
.ft R
characters\&.

.sp

.I val subbytes 
: 
.B bytes -> int -> int -> t
.sp

.ft B
Digest\&.subbytes s ofs len
.ft R
returns the digest of the subsequence
of 
.ft B
s
.ft R
starting at index 
.ft B
ofs
.ft R
and containing 
.ft B
len
.ft R
bytes\&.

.sp
.B "Since"
4.02.0

.sp

.I val channel 
: 
.B in_channel -> int -> t
.sp
If 
.ft B
len
.ft R
is nonnegative, 
.ft B
Digest\&.channel ic len
.ft R
reads 
.ft B
len
.ft R
characters from channel 
.ft B
ic
.ft R
and returns their digest, or raises
.ft B
End_of_file
.ft R
if end\-of\-file is reached before 
.ft B
len
.ft R
characters
are read\&.  If 
.ft B
len
.ft R
is negative, 
.ft B
Digest\&.channel ic len
.ft R
reads
all characters from 
.ft B
ic
.ft R
until end\-of\-file is reached and return
their digest\&.

.sp

.I val file 
: 
.B string -> t
.sp
Return the digest of the file whose name is given\&.

.sp

.I val output 
: 
.B out_channel -> t -> unit
.sp
Write a digest on the given output channel\&.

.sp

.I val input 
: 
.B in_channel -> t
.sp
Read a digest from the given input channel\&.

.sp

.I val to_hex 
: 
.B t -> string
.sp
Return the printable hexadecimal representation of the given digest\&.

.sp
.B "Raises Invalid_argument"
if the argument is not exactly 16 bytes\&.

.sp

.I val from_hex 
: 
.B string -> t
.sp
Convert a hexadecimal representation back into the corresponding digest\&.

.sp
.B "Since"
4.00.0

.sp
.B "Raises Invalid_argument"
if the argument is not exactly 32 hexadecimal
characters\&.

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