1/*  Part of SWI-Prolog
   2
   3    Author:        Jan Wielemaker
   4    E-mail:        J.Wielemaker@vu.nl
   5    WWW:           http://www.swi-prolog.org
   6    Copyright (c)  2007-2013, University of Amsterdam
   7                              VU University Amsterdam
   8    All rights reserved.
   9
  10    Redistribution and use in source and binary forms, with or without
  11    modification, are permitted provided that the following conditions
  12    are met:
  13
  14    1. Redistributions of source code must retain the above copyright
  15       notice, this list of conditions and the following disclaimer.
  16
  17    2. Redistributions in binary form must reproduce the above copyright
  18       notice, this list of conditions and the following disclaimer in
  19       the documentation and/or other materials provided with the
  20       distribution.
  21
  22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33    POSSIBILITY OF SUCH DAMAGE.
  34*/
  35
  36:- module(crypto_hash,
  37          [ sha_hash/3,                 % +Data, -Hash, +Options
  38            sha_new_ctx/2,              % -NewContext, +Options
  39            sha_hash_ctx/4,             % +OldCtx, +Data, -NewCtx, -Hash
  40            hmac_sha/4,                 % +Key, +Data, -Hash, +Options
  41            file_sha1/2,                % +File, -SHA1
  42            hash_atom/2                 % +Hash, -HexAtom
  43          ]).
  44:- use_module(library(shlib)).
  45
  46:- use_foreign_library(foreign(sha4pl)).
  47
  48/** <module> SHA secure hashes
  49
  50This library provides a  lightweight   implementation  for computing SHA
  51secure  hashes.  A  general  secure  hash    interface  is  provided  by
  52library(crypto), part of the `ssl` package.
  53
  54@see library(md5), library(hash_stream) and library(crypto).
  55*/
  56
  57%!  sha_hash(+Data, -Hash, +Options) is det
  58%
  59%   Hash is the SHA hash of Data, The conversion is controlled
  60%   by Options:
  61%
  62%     * algorithm(+Algorithm)
  63%     One of =sha1= (default), =sha224=, =sha256=, =sha384= or
  64%     =sha512=
  65%     * encoding(+Encoding)
  66%     If Data is a sequence of character _codes_, this must be
  67%     translated into a sequence of _bytes_, because that is what
  68%     the hashing requires.  The default encoding is =utf8=.  The
  69%     other meaningful value is =octet=, claiming that Data contains
  70%     raw bytes.
  71%
  72%   @param  Data is either an atom, string or code-list
  73%   @param  Hash is a packed string
  74
  75%!  sha_new_ctx(-NewContext, +Options) is det
  76%
  77%   NewContext is unified with the empty SHA computation context
  78%   (which includes the Options.)  It could later be passed to
  79%   sha_hash_ctx/4. For Options, see sha_hash/3.
  80%
  81%   @param  NewContext is an opaque pure Prolog term that is
  82%           subject to garbage collection.
  83
  84%!  sha_hash_ctx(+OldContext, +Data, -NewContext, -Hash) is det
  85%
  86%   Hash is the SHA hash of Data.  NewContext is the new SHA
  87%   computation context, while OldContext is the old.  OldContext
  88%   may be produced by a prior invocation of either sha_new_ctx/3 or
  89%   sha_hash_ctx/4 itself.
  90%
  91%   This predicate allows a SHA function to be computed in chunks,
  92%   which may be important while working with Metalink (RFC 5854),
  93%   BitTorrent or similar technologies, or simply with big files.
  94
  95%!  hmac_sha(+Key, +Data, -Hash, +Options) is det
  96%
  97%   For Options, see sha_hash/3.
  98
  99%!  file_sha1(+File, -SHA1:atom) is det.
 100%
 101%   True when SHA1 is the SHA1 hash for the content of File. Options
 102%   is passed to open/4 and typically used to control whether binary
 103%   or text encoding must be used. The   output is compatible to the
 104%   =sha1sum= program found in many systems.
 105
 106file_sha1(File, Hash) :-
 107    setup_call_cleanup(
 108        open(File, read, In, [type(binary)]),
 109        stream_sha1(In, Hash),
 110        close(In)).
 111
 112stream_sha1(Stream, Hash) :-
 113    sha_new_ctx(Ctx0, [encoding(octet)]),
 114    update_hash(Stream, Ctx0, _Ctx, 0, HashCodes),
 115    hash_atom(HashCodes, Hash).
 116
 117update_hash(In, Ctx0, Ctx, Hash0, Hash) :-
 118    at_end_of_stream(In),
 119    !,
 120    Ctx = Ctx0,
 121    Hash = Hash0.
 122update_hash(In, Ctx0, Ctx, _Hash0, Hash) :-
 123    read_pending_codes(In, Data, []),
 124    sha_hash_ctx(Ctx0, Data, Ctx1, Hash1),
 125    update_hash(In, Ctx1, Ctx, Hash1, Hash).
 126
 127
 128
 129%!  hash_atom(+HashCodes, -HexAtom) is det.
 130%
 131%   Convert a list of bytes (integers 0..255) into the usual
 132%   hexadecimal notation.  E.g.
 133%
 134%     ==
 135%     ?- sha_hash('SWI-Prolog', Hash, []),
 136%        hash_atom(Hash, Hex).
 137%     Hash = [61, 128, 252, 38, 121, 69, 229, 85, 199|...],
 138%     Hex = '3d80fc267945e555c730403bd0ab0716e2a68c68'.
 139%     ==
 140
 141hash_atom(Codes, Hash) :-
 142    phrase(bytes_hex(Codes), HexCodes),
 143    atom_codes(Hash, HexCodes).
 144
 145bytes_hex([]) --> [].
 146bytes_hex([H|T]) -->
 147    { High is H>>4,
 148      Low is H /\ 0xf,
 149      code_type(C0, xdigit(High)),
 150      code_type(C1, xdigit(Low))
 151    },
 152    [C0,C1],
 153    bytes_hex(T).