Prolog: md5 predicate

Question

I'm trying to write a md5 predicate that verifies the following:

md5("my string", "my md5").

A truth instance of such predicate would be

md5("long live and prosper", "bf1835ce984d2a97d31409394fe00e9a").

I looked into docs, and I found this: http://www.swi-prolog.org/pldoc/doc_for?object=crypt/2

?- phrase("$1$", E, _),
   crypt("My password", E),
   format('~s~n', [E]).

anyway, I cannot get it to work. I'm sure I'm missing something as I'm quite new in prolog. Any hint?

EDIT

For a better explanation, I assume to create a clause similar to this:

md5(P, M):-
   phrase("$1$", E, _),
   crypt(P, E),
   name(M, E),
   format('~s~n', [E]).

?- md5("long live and prosper", "bf1835ce984d2a97d31409394fe00e9a").
   $1$AtnbRJvB$cZ4gZvG2Glelv8hfWztcY/
   false.

Thanks

(Prolog implementation: swi-prolog on Mac OSX El Capitan)

Answer 1

In SWI-Prolog there is also

library(md5): MD5 hashes: Compute MD5 hashes from a Prolog string. This is a rather short-term solution waiting for a more general interface to the libcrypto functions of OpenSSL.

(a subchapter of this is md5_hash).

This is inside the SWI-Prolog C-library and it must be loaded using use_module(library(md5)).

... Unfortunately this doesn't work on my Fedora 24. The RPM package pl-7.2.3-3.fc24.x86_64 seems incomplete. There is no file /usr/lib64/swipl-7.2.3/library/md5.pl and indeed:

?- use_module(library(md5)).
ERROR: source_sink `library(md5)' does not exist

WHY!!

On the other hand, we have module "sha" (/usr/lib64/swipl-7.2.3/library/sha.pl). As I just want a hash value, this seems good enough:

library(sha): SHA1 and SHA2 Secure Hash Algorithms: The library library(sha) provides Secure Hash Algorihms approved by FIPS (Federal Information Processing Standard).

Ok, so:

?- use_module(library(sha)).
true.

?- sha_hash("Beyond the Aquila Rift",H,[algorithm(sha256),encoding(utf8)]),hash_atom(H,Hex).
H = [122, 123, 130, 89, 90, 210, 207, 106, 48|...],
Hex = '7a7b82595ad2cf6a30c2ee66672f53e0d630d4c8742d914e73c6761edc9186d2'.

?- sha_hash("Beyond the Aquila Rift",H,[algorithm(sha1),encoding(utf8)]),hash_atom(H,Hex).
H = [7, 152, 27, 81, 140, 122, 225, 76, 238|...],
Hex = '07981b518c7ae14cee70563d87d56db53656232c'.

Noice!

Answer 2

although deprecated, the functionality you're looking for is available

?- use_module(library(semweb/rdf_db)).
true.

?- rdf_atom_md5("long live and prosper", 1, MD5).
MD5 = bf1835ce984d2a97d31409394fe00e9a.