ADDED: HMAC-based key derivation (HKDF) via crypto_data_hkdf/4
This is useful to generate keys and initialization vectors from suitable input keying material, so that future predicates for symmetric encryption can be used with appropriate parameters.
This commit is contained in:
Markus Triska
@@ -14,12 +14,13 @@
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:- module(crypto, [hex_bytes/2,
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crypto_n_random_bytes/2,
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crypto_data_hash/3,
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crypto_data_hash/3, % +Data, -Hash, +Options
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crypto_data_hkdf/4, % +Data, +Length, -Bytes, +Options
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crypto_name_curve/2, % +Name, -Curve
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crypto_curve_order/2, % +Curve, -Order
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crypto_curve_generator/2, % +Curve, -Generator
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crypto_curve_scalar_mult/4 % +Curve, +Scalar, +Point, -Result
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]).
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]).
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:- use_module(library(error)).
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:- use_module(library(lists)).
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@@ -52,9 +53,7 @@ hex_bytes(Hs, Bytes) :-
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true
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; domain_error(hex_encoding, Hs, hex_bytes/2)
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)
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; must_be(list, Bytes),
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maplist(must_be(integer), Bytes),
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must_be_bytes(Bytes, hex_bytes/2),
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; must_be_bytes(Bytes, hex_bytes/2),
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phrase(bytes_hex(Bytes), Hs)
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).
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@@ -79,6 +78,8 @@ char_hexval(C, H) :- nth0(H, "0123456789ABCDEF", C), !.
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must_be_bytes(Bytes, Context) :-
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must_be(list, Bytes),
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maplist(must_be(integer), Bytes),
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( member(B, Bytes), \+ between(0, 255, B) ->
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type_error(byte, B, Context)
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; true
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@@ -86,6 +87,9 @@ must_be_bytes(Bytes, Context) :-
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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Cryptographically secure random numbers
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=======================================
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crypto_n_random_bytes(+N, -Bytes) is det
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Bytes is unified with a list of N cryptographically secure
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@@ -135,10 +139,14 @@ crypto_n_random_bytes(N, Bs) :-
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crypto_random_byte(B) :- '$crypto_random_byte'(B).
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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Hashing
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=======
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crypto_data_hash(+Data, -Hash, +Options)
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Where Data is a list of bytes (integers between 0 and 255),
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and Hash is the computed hash as a list of hexadecimal characters.
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Where Data is a list of bytes (integers between 0 and 255) or
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characters, and Hash is the computed hash as a list of hexadecimal
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characters.
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The single supported option is:
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@@ -153,27 +161,43 @@ crypto_random_byte(B) :- '$crypto_random_byte'(B).
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Example:
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?- crypto_data_hash([0'a,0'b,0'c], Hs, [algorithm(sha256)]).
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?- crypto_data_hash("abc", Hs, [algorithm(sha256)]).
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Hs = "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
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; false.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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crypto_data_hash(Data, Hash, Options) :-
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must_be(list, Data),
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must_be_bytes(Data, crypto_data_hash/3),
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must_be(list, Options),
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( Options = [algorithm(A)] -> true
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; true
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),
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( var(A) -> A = sha256
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; true
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),
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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SHA256 is the current default for several hash-related predicates.
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It is deemed sufficiently secure for the foreseeable future. Yet,
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application programmers must be aware that the default may change in
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future versions. The hash predicates all yield the algorithm they
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used if a Prolog variable is used for the pertaining option.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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crypto_data_hash(Data0, Hash, Options0) :-
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chars_bytes_(Data0, Data, crypto_data_hash/3),
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must_be(list, Options0),
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functor_hash_options(algorithm, A, Options0, _),
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( hash_algorithm(A) -> true
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; domain_error(hash_algorithm, A, crypto_data_hash/3)
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),
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'$crypto_data_hash'(Data, HashBytes, A),
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hex_bytes(Hash, HashBytes).
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default_hash(sha256).
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functor_hash_options(F, Hash, Options0, [Option|Options]) :-
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Option =.. [F,Hash],
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( select(Option, Options0, Options) ->
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( var(Hash) ->
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default_hash(Hash)
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; must_be(atom, Hash)
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)
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; Options = Options0,
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default_hash(Hash)
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).
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hash_algorithm(ripemd160).
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hash_algorithm(sha256).
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hash_algorithm(sha512).
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@@ -181,6 +205,60 @@ hash_algorithm(sha384).
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hash_algorithm(sha512_256).
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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crypto_data_hkdf(+Data, +Length, -Bytes, +Options) is det.
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Concentrate possibly dispersed entropy of Data and then expand it
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to the desired length. Data is a list of bytes or characters.
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Bytes is unified with a list of bytes of length Length, and is
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suitable as input keying material and initialization vectors to
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symmetric encryption algorithms.
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Admissible options are:
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- algorithm(+Algorithm)
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A hashing algorithm as specified to crypto_data_hash/3. The
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default is a cryptographically secure algorithm. If you
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specify a variable, then it is unified with the algorithm
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that was used, which is a cryptographically secure algorithm.
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- info(+Info)
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Optional context and application specific information,
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specified as a list of bytes or characters. The default is [].
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- salt(+List)
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Optionally, a list of bytes that are used as salt. The
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default is all zeroes.
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The `info/1` option can be used to generate multiple keys from a
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single master key, using for example values such as "key" and
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"iv", or the name of a file that is to be encrypted.
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See crypto_n_random_bytes/2 to obtain a suitable salt.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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crypto_data_hkdf(Data0, L, Bytes, Options0) :-
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functor_hash_options(algorithm, Algorithm, Options0, Options),
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chars_bytes_(Data0, Data, crypto_data_hkdf/4),
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option(salt(SaltBytes), Options, []),
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must_be_bytes(SaltBytes, crypto_data_hkdf/4),
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option(info(Info0), Options, []),
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chars_bytes_(Info0, Info, crypto_data_hkdf/4),
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'$crypto_data_hkdf'(Data, SaltBytes, Info, Algorithm, L, Bytes).
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option(What, Options, Default) :-
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( member(What, Options) -> true
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; What =.. [_,Default]
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).
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chars_bytes_(Cs, Bytes, Context) :-
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must_be(list, Cs),
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( maplist(integer, Cs) -> Bytes = Cs
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; % use chars_utf8bytes/2 here once it becomes available!
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maplist(atom_codes, Cs, Css),
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append(Css, Bytes)
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),
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must_be_bytes(Bytes, Context).
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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Modular multiplicative inverse.
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