1/* Part of SWI-Prolog 2 3 Author: Markus Triska and Matt Lilley 4 WWW: http://www.swi-prolog.org 5 Copyright (c) 2004-2017, SWI-Prolog Foundation 6 VU University Amsterdam 7 All rights reserved. 8 9 Redistribution and use in source and binary forms, with or without 10 modification, are permitted provided that the following conditions 11 are met: 12 13 1. Redistributions of source code must retain the above copyright 14 notice, this list of conditions and the following disclaimer. 15 16 2. Redistributions in binary form must reproduce the above copyright 17 notice, this list of conditions and the following disclaimer in 18 the documentation and/or other materials provided with the 19 distribution. 20 21 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 29 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 31 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 POSSIBILITY OF SUCH DAMAGE. 33*/ 34 35:- module(crypto, 36 [ crypto_n_random_bytes/2, % +N, -Bytes 37 crypto_data_hash/3, % +Data, -Hash, +Options 38 crypto_file_hash/3, % +File, -Hash, +Options 39 crypto_context_new/2, % -Context, +Options 40 crypto_data_context/3, % +Data, +C0, -C 41 crypto_context_hash/2, % +Context, -Hash 42 crypto_open_hash_stream/3, % +InStream, -HashStream, +Options 43 crypto_stream_hash/2, % +HashStream, -Hash 44 crypto_password_hash/2, % +Password, ?Hash 45 crypto_password_hash/3, % +Password, ?Hash, +Options 46 crypto_data_hkdf/4, % +Data, +Length, -Bytes, +Options 47 ecdsa_sign/4, % +Key, +Data, -Signature, +Options 48 ecdsa_verify/4, % +Key, +Data, +Signature, +Options 49 crypto_data_decrypt/6, % +CipherText, +Algorithm, +Key, +IV, -PlainText, +Options 50 crypto_data_encrypt/6, % +PlainText, +Algorithm, +Key, +IV, -CipherText, +Options 51 hex_bytes/2, % ?Hex, ?List 52 rsa_private_decrypt/4, % +Key, +Ciphertext, -Plaintext, +Enc 53 rsa_private_encrypt/4, % +Key, +Plaintext, -Ciphertext, +Enc 54 rsa_public_decrypt/4, % +Key, +Ciphertext, -Plaintext, +Enc 55 rsa_public_encrypt/4, % +Key, +Plaintext, -Ciphertext, +Enc 56 rsa_sign/4, % +Key, +Data, -Signature, +Options 57 rsa_verify/4, % +Key, +Data, +Signature, +Options 58 crypto_modular_inverse/3, % +X, +M, -Y 59 crypto_generate_prime/3, % +N, -P, +Options 60 crypto_is_prime/2, % +P, +Options 61 crypto_name_curve/2, % +Name, -Curve 62 crypto_curve_order/2, % +Curve, -Order 63 crypto_curve_generator/2, % +Curve, -Generator 64 crypto_curve_scalar_mult/4 % +Curve, +Scalar, +Point, -Result 65 ]). 66:- autoload(library(apply),[foldl/4,maplist/3]). 67:- autoload(library(base64),[base64_encoded/3]). 68:- autoload(library(error),[must_be/2,domain_error/2]). 69:- autoload(library(lists),[select/3,reverse/2]). 70:- autoload(library(option),[option/3,option/2]). 71 72:- use_foreign_library(foreign(crypto4pl)). 73 74 75/** <module> Cryptography and authentication library 76 77This library provides bindings to functionality of OpenSSL that is 78related to cryptography and authentication, not necessarily involving 79connections, sockets or streams. 80 81The hash functionality of this library subsumes and extends that of 82`library(sha)`, `library(hash_stream)` and `library(md5)` by providing a 83unified interface to all available digest algorithms. 84 85The underlying OpenSSL library (`libcrypto`) is dynamically loaded if 86_either_ `library(crypto)` or `library(ssl)` are loaded. Therefore, if 87your application uses `library(ssl)`, you can use `library(crypto)` for 88hashing without increasing the memory footprint of your application. In 89other cases, the specialised hashing libraries are more lightweight but 90less general alternatives to `library(crypto)`. 91 92@author [Markus Triska](https://www.metalevel.at) 93@author Matt Lilley 94*/ 95 96%% crypto_n_random_bytes(+N, -Bytes) is det 97% 98% Bytes is unified with a list of N cryptographically secure 99% pseudo-random bytes. Each byte is an integer between 0 and 255. If 100% the internal pseudo-random number generator (PRNG) has not been 101% seeded with enough entropy to ensure an unpredictable byte 102% sequence, an exception is thrown. 103% 104% One way to relate such a list of bytes to an _integer_ is to use 105% CLP(FD) constraints as follows: 106% 107% == 108% :- use_module(library(clpfd)). 109% 110% bytes_integer(Bs, N) :- 111% foldl(pow, Bs, 0-0, N-_). 112% 113% pow(B, N0-I0, N-I) :- 114% B in 0..255, 115% N #= N0 + B*256^I0, 116% I #= I0 + 1. 117% == 118% 119% With this definition, you can generate a random 256-bit integer 120% _from_ a list of 32 random _bytes_: 121% 122% == 123% ?- crypto_n_random_bytes(32, Bs), 124% bytes_integer(Bs, I). 125% Bs = [98, 9, 35, 100, 126, 174, 48, 176, 246|...], 126% I = 109798276762338328820827...(53 digits omitted). 127% == 128% 129% The above relation also works in the other direction, letting you 130% translate an integer _to_ a list of bytes. In addition, you can 131% use hex_bytes/2 to convert bytes to _tokens_ that can be easily 132% exchanged in your applications. This also works if you have 133% compiled SWI-Prolog without support for large integers. 134 135 136/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 137 SHA256 is the current default for several hash-related predicates. 138 It is deemed sufficiently secure for the foreseeable future. Yet, 139 application programmers must be aware that the default may change in 140 future versions. The hash predicates all yield the algorithm they 141 used if a Prolog variable is used for the pertaining option. 142- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 143 144default_hash(sha256). 145 146functor_hash_options(F, Hash, Options0, [Option|Options]) :- 147 Option =.. [F,Hash], 148 ( select(Option, Options0, Options) -> 149 ( var(Hash) -> 150 default_hash(Hash) 151 ; must_be(atom, Hash) 152 ) 153 ; Options = Options0, 154 default_hash(Hash) 155 ). 156 157 158%% crypto_data_hash(+Data, -Hash, +Options) is det 159% 160% Hash is the hash of Data. The conversion is controlled 161% by Options: 162% 163% * algorithm(+Algorithm) 164% One of =md5= (_insecure_), =sha1= (_insecure_), =ripemd160=, 165% =sha224=, =sha256=, =sha384=, =sha512=, =sha3_224=, =sha3_256=, 166% =sha3_384=, =sha3_512=, =blake2s256= or =blake2b512=. The BLAKE 167% digest algorithms require OpenSSL 1.1.0 or greater, and the SHA-3 168% algorithms require OpenSSL 1.1.1 or greater. The default is a 169% cryptographically secure algorithm. If you specify a variable, 170% then that variable is unified with the algorithm that was used. 171% * encoding(+Encoding) 172% If Data is a sequence of character _codes_, this must be 173% translated into a sequence of _bytes_, because that is what 174% the hashing requires. The default encoding is =utf8=. The 175% other meaningful value is =octet=, claiming that Data contains 176% raw bytes. 177% * hmac(+Key) 178% If this option is specified, a _hash-based message authentication 179% code_ (HMAC) is computed, using the specified Key which is either 180% an atom, string or list of _bytes_. Any of the available digest 181% algorithms can be used with this option. The cryptographic 182% strength of the HMAC depends on that of the chosen algorithm and 183% also on the key. This option requires OpenSSL 1.1.0 or greater. 184% 185% @param Data is either an atom, string or code-list 186% @param Hash is an atom that represents the hash in hexadecimal encoding. 187% 188% @see hex_bytes/2 for conversion between hexadecimal encoding and 189% lists of bytes. 190% @see crypto_password_hash/2 for the important use case of passwords. 191 192crypto_data_hash(Data, Hash, Options) :- 193 crypto_context_new(Context0, Options), 194 crypto_data_context(Data, Context0, Context), 195 crypto_context_hash(Context, Hash). 196 197%! crypto_file_hash(+File, -Hash, +Options) is det. 198% 199% True if Hash is the hash of the content of File. For Options, 200% see crypto_data_hash/3. 201 202crypto_file_hash(File, Hash, Options) :- 203 setup_call_cleanup(open(File, read, In, [type(binary)]), 204 crypto_stream_hash(In, Hash, Options), 205 close(In)). 206 207crypto_stream_hash(Stream, Hash, Options) :- 208 crypto_context_new(Context0, Options), 209 update_hash(Stream, Context0, Context), 210 crypto_context_hash(Context, Hash). 211 212update_hash(In, Context0, Context) :- 213 ( at_end_of_stream(In) 214 -> Context = Context0 215 ; read_pending_codes(In, Data, []), 216 crypto_data_context(Data, Context0, Context1), 217 update_hash(In, Context1, Context) 218 ). 219 220 221%! crypto_context_new(-Context, +Options) is det. 222% 223% Context is unified with the empty context, taking into account 224% Options. The context can be used in crypto_data_context/3. For 225% Options, see crypto_data_hash/3. 226% 227% @param Context is an opaque pure Prolog term that is subject to 228% garbage collection. 229 230crypto_context_new(Context, Options0) :- 231 functor_hash_options(algorithm, _, Options0, Options), 232 '_crypto_context_new'(Context, Options). 233 234 235%! crypto_data_context(+Data, +Context0, -Context) is det 236% 237% Context0 is an existing computation context, and Context is the 238% new context after hashing Data in addition to the previously 239% hashed data. Context0 may be produced by a prior invocation of 240% either crypto_context_new/2 or crypto_data_context/3 itself. 241% 242% This predicate allows a hash to be computed in chunks, which may 243% be important while working with Metalink (RFC 5854), BitTorrent 244% or similar technologies, or simply with big files. 245 246crypto_data_context(Data, Context0, Context) :- 247 '_crypto_hash_context_copy'(Context0, Context), 248 '_crypto_update_hash_context'(Data, Context). 249 250 251%! crypto_context_hash(+Context, -Hash) 252% 253% Obtain the hash code of Context. Hash is an atom representing 254% the hash code that is associated with the current state of the 255% computation context Context. 256 257crypto_context_hash(Context, Hash) :- 258 '_crypto_hash_context_copy'(Context, Copy), 259 '_crypto_hash_context_hash'(Copy, List), 260 hex_bytes(Hash, List). 261 262%! crypto_open_hash_stream(+OrgStream, -HashStream, +Options) is det. 263% 264% Open a filter stream on OrgStream that maintains a hash. The hash 265% can be retrieved at any time using crypto_stream_hash/2. Available 266% Options in addition to those of crypto_data_hash/3 are: 267% 268% - close_parent(+Bool) 269% If `true` (default), closing the filter stream also closes the 270% original (parent) stream. 271 272crypto_open_hash_stream(OrgStream, HashStream, Options) :- 273 crypto_context_new(Context, Options), 274 '_crypto_open_hash_stream'(OrgStream, HashStream, Context). 275 276 277%! crypto_stream_hash(+HashStream, -Hash) is det. 278% 279% Unify Hash with a hash for the bytes sent to or read from 280% HashStream. Note that the hash is computed on the stream 281% buffers. If the stream is an output stream, it is first flushed 282% and the Digest represents the hash at the current location. If 283% the stream is an input stream the Digest represents the hash of 284% the processed input including the already buffered data. 285 286crypto_stream_hash(Stream, Hash) :- 287 '_crypto_stream_hash_context'(Stream, Context), 288 crypto_context_hash(Context, Hash). 289 290/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 291 The so-called modular crypt format (MCF) is a standard for encoding 292 password hash strings. However, there's no official specification 293 document describing it. Nor is there a central registry of 294 identifiers or rules. This page describes what is known about it: 295 296 https://pythonhosted.org/passlib/modular_crypt_format.html 297 298 As of 2016, the MCF is deprecated in favor of the PHC String Format: 299 300 https://github.com/P-H-C/phc-string-format/blob/master/phc-sf-spec.md 301 302 This is what we are using below. For the time being, it is best to 303 treat these hashes as opaque atoms in applications. Please let me 304 know if you need to rely on any specifics of this format. 305- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 306 307%! crypto_password_hash(+Password, ?Hash) is semidet. 308% 309% If Hash is instantiated, the predicate succeeds _iff_ the hash 310% matches the given password. Otherwise, the call is equivalent to 311% crypto_password_hash(Password, Hash, []) and computes a 312% password-based hash using the default options. 313 314crypto_password_hash(Password, Hash) :- 315 ( nonvar(Hash) -> 316 must_be(atom, Hash), 317 split_string(Hash, "$", "$", ["pbkdf2-sha512",Ps,SaltB64,HashB64]), 318 atom_to_term(Ps, t=Iterations, []), 319 bytes_base64(SaltBytes, SaltB64), 320 bytes_base64(HashBytes, HashB64), 321 '_crypto_password_hash'(Password, SaltBytes, Iterations, HashBytes) 322 ; crypto_password_hash(Password, Hash, []) 323 ). 324 325%! crypto_password_hash(+Password, -Hash, +Options) is det. 326% 327% Derive Hash based on Password. This predicate is similar to 328% crypto_data_hash/3 in that it derives a hash from given data. 329% However, it is tailored for the specific use case of 330% _passwords_. One essential distinction is that for this use case, 331% the derivation of a hash should be _as slow as possible_ to 332% counteract brute-force attacks over possible passwords. 333% 334% Another important distinction is that equal passwords must yield, 335% with very high probability, _different_ hashes. For this reason, 336% cryptographically strong random numbers are automatically added to 337% the password before a hash is derived. 338% 339% Hash is unified with an atom that contains the computed hash and all 340% parameters that were used, except for the password. Instead of 341% storing passwords, store these hashes. Later, you can verify the 342% validity of a password with crypto_password_hash/2, comparing the 343% then entered password to the stored hash. If you need to export this 344% atom, you should treat it as opaque ASCII data with up to 255 bytes 345% of length. The maximal length may increase in the future. 346% 347% Admissible options are: 348% 349% - algorithm(+Algorithm) 350% The algorithm to use. Currently, the only available algorithm 351% is =|pbkdf2-sha512|=, which is therefore also the default. 352% - cost(+C) 353% C is an integer, denoting the binary logarithm of the number 354% of _iterations_ used for the derivation of the hash. This 355% means that the number of iterations is set to 2^C. Currently, 356% the default is 17, and thus more than one hundred _thousand_ 357% iterations. You should set this option as high as your server 358% and users can tolerate. The default is subject to change and 359% will likely increase in the future or adapt to new algorithms. 360% - salt(+Salt) 361% Use the given list of bytes as salt. By default, 362% cryptographically secure random numbers are generated for this 363% purpose. The default is intended to be secure, and constitutes 364% the typical use case of this predicate. 365% 366% Currently, PBKDF2 with SHA-512 is used as the hash derivation 367% function, using 128 bits of salt. All default parameters, including 368% the algorithm, are subject to change, and other algorithms will also 369% become available in the future. Since computed hashes store all 370% parameters that were used during their derivation, such changes will 371% not affect the operation of existing deployments. Note though that 372% new hashes will then be computed with the new default parameters. 373% 374% @see crypto_data_hkdf/4 for generating keys from Hash. 375 376crypto_password_hash(Password, Hash, Options) :- 377 must_be(list, Options), 378 option(cost(C), Options, 17), 379 Iterations is 2^C, 380 Algorithm = 'pbkdf2-sha512', % current default and only option 381 option(algorithm(Algorithm), Options, Algorithm), 382 ( option(salt(SaltBytes), Options) -> 383 true 384 ; crypto_n_random_bytes(16, SaltBytes) 385 ), 386 '_crypto_password_hash'(Password, SaltBytes, Iterations, HashBytes), 387 bytes_base64(HashBytes, HashB64), 388 bytes_base64(SaltBytes, SaltB64), 389 format(atom(Hash), 390 "$pbkdf2-sha512$t=~d$~w$~w", [Iterations,SaltB64,HashB64]). 391 392 393/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 394 Bidirectional Bytes <-> Base64 conversion as required by PHC format. 395 396 Note that *no padding* must be used, and that we must be able 397 to encode the whole range of bytes, not only UTF-8 sequences! 398- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 399 400bytes_base64(Bytes, Base64) :- 401 ( var(Bytes) -> 402 base64_encoded(Atom, Base64, [padding(false)]), 403 atom_codes(Atom, Bytes) 404 ; atom_codes(Atom, Bytes), 405 base64_encoded(Atom, Base64, [padding(false)]) 406 ). 407 408 409%! crypto_data_hkdf(+Data, +Length, -Bytes, +Options) is det. 410% 411% Concentrate possibly dispersed entropy of Data and then expand it to 412% the desired length. Bytes is unified with a list of _bytes_ of 413% length Length, and is suitable as input keying material and 414% initialization vectors to the symmetric encryption predicates. 415% 416% Admissible options are: 417% 418% - algorithm(+Algorithm) 419% A hashing algorithm as specified to crypto_data_hash/3. The 420% default is a cryptographically secure algorithm. If you 421% specify a variable, then it is unified with the algorithm 422% that was used. 423% - info(+Info) 424% Optional context and application specific information, 425% specified as an atom, string or list of _bytes_. The default 426% is the zero length atom ''. 427% - salt(+List) 428% Optionally, a list of _bytes_ that are used as salt. The 429% default is all zeroes. 430% - encoding(+Atom) 431% Either =|utf8|= (default) or =|octet|=, denoting 432% the representation of Data as in crypto_data_hash/3. 433% 434% The `info/1` option can be used to generate multiple keys from a 435% single master key, using for example values such as =|key|= and 436% =|iv|=, or the name of a file that is to be encrypted. 437% 438% This predicate requires OpenSSL 1.1.0 or greater. 439% 440% @see crypto_n_random_bytes/2 to obtain a suitable salt. 441 442 443crypto_data_hkdf(Data, L, Bytes, Options0) :- 444 functor_hash_options(algorithm, Algorithm, Options0, Options), 445 option(salt(SaltBytes), Options, []), 446 option(info(Info), Options, ''), 447 option(encoding(Enc), Options, utf8), 448 '_crypto_data_hkdf'(Data, SaltBytes, Info, Algorithm, Enc, L, Bytes). 449 450%! ecdsa_sign(+Key, +Data, -Signature, +Options) 451% 452% Create an ECDSA signature for Data with EC private key Key. 453% Among the most common cases is signing a hash that was created 454% with crypto_data_hash/3 or other predicates of this library. For 455% this reason, the default encoding (`hex`) assumes that Data is 456% an atom, string, character list or code list representing the 457% data in hexadecimal notation. See rsa_sign/4 for an example. 458% 459% Options: 460% 461% - encoding(+Encoding) 462% Encoding to use for Data. Default is `hex`. Alternatives 463% are `octet`, `utf8` and `text`. 464 465ecdsa_sign(private_key(ec(Private,Public0,Curve)), Data0, Signature, Options) :- 466 option(encoding(Enc0), Options, hex), 467 hex_encoding(Enc0, Data0, Enc, Data), 468 hex_bytes(Public0, Public), 469 '_crypto_ecdsa_sign'(ec(Private,Public,Curve), Data, Enc, Signature). 470 471hex_encoding(hex, Data0, octet, Data) :- !, 472 hex_bytes(Data0, Data). 473hex_encoding(Enc, Data, Enc, Data). 474 475%! ecdsa_verify(+Key, +Data, +Signature, +Options) is semidet. 476% 477% True iff Signature can be verified as the ECDSA signature for 478% Data, using the EC public key Key. 479% 480% Options: 481% 482% - encoding(+Encoding) 483% Encoding to use for Data. Default is `hex`. Alternatives 484% are `octet`, `utf8` and `text`. 485 486ecdsa_verify(public_key(ec(Private,Public0,Curve)), Data0, Signature0, Options) :- 487 option(encoding(Enc0), Options, hex), 488 hex_encoding(Enc0, Data0, Enc, Data), 489 hex_bytes(Public0, Public), 490 hex_bytes(Signature0, Signature), 491 '_crypto_ecdsa_verify'(ec(Private,Public,Curve), Data, Enc, Signature). 492 493 494%! hex_bytes(?Hex, ?List) is det. 495% 496% Relation between a hexadecimal sequence and a list of bytes. Hex 497% is an atom, string, list of characters or list of codes in 498% hexadecimal encoding. This is the format that is used by 499% crypto_data_hash/3 and related predicates to represent _hashes_. 500% Bytes is a list of _integers_ between 0 and 255 that represent the 501% sequence as a list of bytes. At least one of the arguments must 502% be instantiated. When converting List _to_ Hex, an _atom_ is used 503% to represent the sequence of hexadecimal digits. 504% 505% Example: 506% 507% == 508% ?- hex_bytes('501ACE', Bs). 509% Bs = [80, 26, 206]. 510% == 511% 512% @see base64_encoded/3 for Base64 encoding, which is often used to 513% transfer or embed binary data in applications. 514 515hex_bytes(Hs, Bytes) :- 516 ( ground(Hs) -> 517 string_chars(Hs, Chars), 518 ( phrase(hex_bytes(Chars), Bytes) 519 -> true 520 ; domain_error(hex_encoding, Hs) 521 ) 522 ; must_be(list(between(0,255)), Bytes), 523 phrase(bytes_hex(Bytes), Chars), 524 atom_chars(Hs, Chars) 525 ). 526 527hex_bytes([]) --> []. 528hex_bytes([H1,H2|Hs]) --> [Byte], 529 { char_type(H1, xdigit(High)), 530 char_type(H2, xdigit(Low)), 531 Byte is High*16 + Low }, 532 hex_bytes(Hs). 533 534bytes_hex([]) --> []. 535bytes_hex([B|Bs]) --> 536 { High is B>>4, 537 Low is B /\ 0xf, 538 char_type(C0, xdigit(High)), 539 char_type(C1, xdigit(Low)) 540 }, 541 [C0,C1], 542 bytes_hex(Bs). 543 544%! rsa_private_decrypt(+PrivateKey, +CipherText, -PlainText, +Options) is det. 545%! rsa_private_encrypt(+PrivateKey, +PlainText, -CipherText, +Options) is det. 546%! rsa_public_decrypt(+PublicKey, +CipherText, -PlainText, +Options) is det. 547%! rsa_public_encrypt(+PublicKey, +PlainText, -CipherText, +Options) is det. 548% 549% RSA Public key encryption and decryption primitives. A string 550% can be safely communicated by first encrypting it and have the 551% peer decrypt it with the matching key and predicate. The length 552% of the string is limited by the key length. 553% 554% Options: 555% 556% - encoding(+Encoding) 557% Encoding to use for Data. Default is `utf8`. Alternatives 558% are `utf8` and `octet`. 559% 560% - padding(+PaddingScheme) 561% Padding scheme to use. Default is `pkcs1`. Alternatives 562% are `pkcs1_oaep`, `sslv23` and `none`. Note that `none` should 563% only be used if you implement cryptographically sound padding 564% modes in your application code as encrypting unpadded data with 565% RSA is insecure 566% 567% @see load_private_key/3, load_public_key/2 can be use to load 568% keys from a file. The predicate load_certificate/2 can be used 569% to obtain the public key from a certificate. 570% 571% @error ssl_error(Code, LibName, FuncName, Reason) is raised if 572% there is an error, e.g., if the text is too long for the key. 573 574%! rsa_sign(+Key, +Data, -Signature, +Options) is det. 575% 576% Create an RSA signature for Data with private key Key. Options: 577% 578% - type(+Type) 579% SHA algorithm used to compute the digest. Values are 580% `sha1`, `sha224`, `sha256`, `sha384` or `sha512`. The 581% default is a cryptographically secure algorithm. If you 582% specify a variable, then it is unified with the algorithm that 583% was used. 584% 585% - encoding(+Encoding) 586% Encoding to use for Data. Default is `hex`. Alternatives 587% are `octet`, `utf8` and `text`. 588% 589% This predicate can be used to compute a =|sha256WithRSAEncryption|= 590% signature as follows: 591% 592% ``` 593% sha256_with_rsa(PemKeyFile, Password, Data, Signature) :- 594% Algorithm = sha256, 595% read_key(PemKeyFile, Password, Key), 596% crypto_data_hash(Data, Hash, [algorithm(Algorithm), 597% encoding(octet)]), 598% rsa_sign(Key, Hash, Signature, [type(Algorithm)]). 599% 600% read_key(File, Password, Key) :- 601% setup_call_cleanup( 602% open(File, read, In, [type(binary)]), 603% load_private_key(In, Password, Key), 604% close(In)). 605% ``` 606% 607% Note that a hash that is computed by crypto_data_hash/3 can be 608% directly used in rsa_sign/4 as well as ecdsa_sign/4. 609 610rsa_sign(Key, Data0, Signature, Options0) :- 611 functor_hash_options(type, Type, Options0, Options), 612 option(encoding(Enc0), Options, hex), 613 hex_encoding(Enc0, Data0, Enc, Data), 614 rsa_sign(Key, Type, Enc, Data, Signature). 615 616 617%! rsa_verify(+Key, +Data, +Signature, +Options) is semidet. 618% 619% Verify an RSA signature for Data with public key Key. 620% 621% Options: 622% 623% - type(+Type) 624% SHA algorithm used to compute the digest. Values are `sha1`, 625% `sha224`, `sha256`, `sha384` or `sha512`. The default is the 626% same as for rsa_sign/4. This option must match the algorithm 627% that was used for signing. When operating with different parties, 628% the used algorithm must be communicated over an authenticated 629% channel. 630% 631% - encoding(+Encoding) 632% Encoding to use for Data. Default is `hex`. Alternatives 633% are `octet`, `utf8` and `text`. 634 635rsa_verify(Key, Data0, Signature0, Options0) :- 636 functor_hash_options(type, Type, Options0, Options), 637 option(encoding(Enc0), Options, hex), 638 hex_encoding(Enc0, Data0, Enc, Data), 639 hex_bytes(Signature0, Signature), 640 rsa_verify(Key, Type, Enc, Data, Signature). 641 642%! crypto_data_decrypt(+CipherText, 643%! +Algorithm, 644%! +Key, 645%! +IV, 646%! -PlainText, 647%! +Options). 648% 649% Decrypt the given CipherText, using the symmetric algorithm 650% Algorithm, key Key, and initialization vector IV, to give PlainText. 651% CipherText must be a string, atom or list of codes or characters, 652% and PlainText is created as a string. Key and IV are typically 653% lists of _bytes_, though atoms and strings are also permitted. 654% Algorithm must be an algorithm which your copy of OpenSSL knows. See 655% crypto_data_encrypt/6 for an example. 656% 657% - encoding(+Encoding) 658% Encoding to use for CipherText. Default is `utf8`. 659% Alternatives are `utf8` and `octet`. 660% 661% - padding(+PaddingScheme) 662% For block ciphers, the padding scheme to use. Default is 663% `block`. You can disable padding by supplying `none` here. 664% 665% - tag(+Tag) 666% For authenticated encryption schemes, the tag must be specified as 667% a list of bytes exactly as they were generated upon encryption. 668% This option requires OpenSSL 1.1.0 or greater. 669% 670% - min_tag_length(+Length) 671% If the tag length is smaller than 16, this option must be used 672% to permit such shorter tags. This is used as a safeguard against 673% truncation attacks, where an attacker provides a short tag that 674% is easier to guess. 675 676crypto_data_decrypt(CipherText, Algorithm, Key, IV, PlainText, Options) :- 677 ( option(tag(Tag), Options) -> 678 option(min_tag_length(MinTagLength), Options, 16), 679 length(Tag, TagLength), 680 compare(C, TagLength, MinTagLength), 681 tag_length_ok(C, Tag) 682 ; Tag = [] 683 ), 684 '_crypto_data_decrypt'(CipherText, Algorithm, Key, IV, 685 Tag, PlainText, Options). 686 687% This test is important to prevent truncation attacks of the tag. 688 689tag_length_ok(=, _). 690tag_length_ok(>, _). 691tag_length_ok(<, Tag) :- domain_error(tag_is_too_short, Tag). 692 693 694%! crypto_data_encrypt(+PlainText, 695%! +Algorithm, 696%! +Key, 697%! +IV, 698%! -CipherText, 699%! +Options). 700% 701% Encrypt the given PlainText, using the symmetric algorithm 702% Algorithm, key Key, and initialization vector (or nonce) IV, to give 703% CipherText. 704% 705% PlainText must be a string, atom or list of codes or characters, and 706% CipherText is created as a string. Key and IV are typically lists 707% of _bytes_, though atoms and strings are also permitted. Algorithm 708% must be an algorithm which your copy of OpenSSL knows 709% about. 710% 711% Keys and IVs can be chosen at random (using for example 712% crypto_n_random_bytes/2) or derived from input keying material (IKM) 713% using for example crypto_data_hkdf/4. This input is often a shared 714% secret, such as a negotiated point on an elliptic curve, or the hash 715% that was computed from a password via crypto_password_hash/3 with a 716% freshly generated and specified _salt_. 717% 718% Reusing the same combination of Key and IV typically leaks at least 719% _some_ information about the plaintext. For example, identical 720% plaintexts will then correspond to identical ciphertexts. For some 721% algorithms, reusing an IV with the same Key has disastrous results 722% and can cause the loss of all properties that are otherwise 723% guaranteed. Especially in such cases, an IV is also called a 724% _nonce_ (number used once). If an IV is not needed for your 725% algorithm (such as =|'aes-128-ecb'|=) then any value can be provided 726% as it will be ignored by the underlying implementation. Note that 727% such algorithms do not provide _semantic security_ and are thus 728% insecure. You should use stronger algorithms instead. 729% 730% It is safe to store and transfer the used initialization vector (or 731% nonce) in plain text, but the key _must be kept secret_. 732% 733% Commonly used algorithms include: 734% 735% $ =|'chacha20-poly1305'|= : 736% A powerful and efficient _authenticated_ encryption scheme, 737% providing secrecy and at the same time reliable protection 738% against undetected _modifications_ of the encrypted data. This 739% is a very good choice for virtually all use cases. It is a 740% _stream cipher_ and can encrypt data of any length up to 256 GB. 741% Further, the encrypted data has exactly the same length 742% as the original, and no padding is used. It requires OpenSSL 743% 1.1.0 or greater. See below for an example. 744% 745% $ =|'aes-128-gcm'|= : 746% Also an authenticated encryption scheme. It uses a 128-bit 747% (i.e., 16 bytes) key and a 96-bit (i.e., 12 bytes) nonce. It 748% requires OpenSSL 1.1.0 or greater. 749% 750% $ =|'aes-128-cbc'|= : 751% A _block cipher_ that provides secrecy, but does not protect 752% against unintended modifications of the cipher text. This 753% algorithm uses 128-bit (16 bytes) keys and initialization 754% vectors. It works with all supported versions of OpenSSL. If 755% possible, consider using an authenticated encryption scheme 756% instead. 757% 758% Options: 759% 760% - encoding(+Encoding) 761% Encoding to use for PlainText. Default is `utf8`. Alternatives 762% are `utf8` and `octet`. 763% 764% - padding(+PaddingScheme) 765% For block ciphers, the padding scheme to use. Default is 766% `block`. You can disable padding by supplying `none` here. If 767% padding is disabled for block ciphers, then the length of the 768% ciphertext must be a multiple of the block size. 769% 770% - tag(-List) 771% For authenticated encryption schemes, List is unified with a 772% list of _bytes_ holding the tag. This tag must be provided for 773% decryption. Authenticated encryption requires OpenSSL 1.1.0 or 774% greater. 775% 776% - tag_length(+Length) 777% For authenticated encryption schemes, the desired length of the 778% tag, specified as the number of bytes. The default is 779% 16. Smaller numbers are not recommended. 780% 781% For example, with OpenSSL 1.1.0 and greater, we can use the ChaCha20 782% stream cipher with the Poly1305 authenticator. This cipher uses a 783% 256-bit key and a 96-bit _nonce_, i.e., 32 and 12 _bytes_, 784% respectively: 785% 786% ``` 787% ?- Algorithm = 'chacha20-poly1305', 788% crypto_n_random_bytes(32, Key), 789% crypto_n_random_bytes(12, IV), 790% crypto_data_encrypt("this is some input", Algorithm, 791% Key, IV, CipherText, [tag(Tag)]), 792% crypto_data_decrypt(CipherText, Algorithm, 793% Key, IV, RecoveredText, [tag(Tag)]). 794% Algorithm = 'chacha20-poly1305', 795% Key = [65, 147, 140, 197, 27, 60, 198, 50, 218|...], 796% IV = [253, 232, 174, 84, 168, 208, 218, 168, 228|...], 797% CipherText = <binary string>, 798% Tag = [248, 220, 46, 62, 255, 9, 178, 130, 250|...], 799% RecoveredText = "this is some input". 800% ``` 801% 802% In this example, we use crypto_n_random_bytes/2 to generate a key 803% and nonce from cryptographically secure random numbers. For 804% repeated applications, you must ensure that a nonce is only used 805% _once_ together with the same key. Note that for _authenticated_ 806% encryption schemes, the _tag_ that was computed during encryption is 807% necessary for decryption. It is safe to store and transfer the tag 808% in plain text. 809% 810% @see crypto_data_decrypt/6. 811% @see hex_bytes/2 for conversion between bytes and hex encoding. 812 813crypto_data_encrypt(PlainText, Algorithm, Key, IV, CipherText, Options) :- 814 ( option(tag(AuthTag), Options) -> 815 option(tag_length(AuthLength), Options, 16) 816 ; AuthTag = _, 817 AuthLength = -1 818 ), 819 '_crypto_data_encrypt'(PlainText, Algorithm, Key, IV, 820 AuthLength, AuthTag, CipherText, Options). 821 822 823%% crypto_modular_inverse(+X, +M, -Y) is det 824% 825% Compute the modular multiplicative inverse of the integer X. Y is 826% unified with an integer such that X*Y is congruent to 1 modulo M. 827 828 829crypto_modular_inverse(X, M, Y) :- 830 integer_serialized(X, XS), 831 integer_serialized(M, MS), 832 '_crypto_modular_inverse'(XS, MS, YHex), 833 hex_to_integer(YHex, Y). 834 835integer_serialized(I, serialized(S)) :- 836 must_be(integer, I), 837 integer_atomic_sign(I, Sign), 838 Abs is abs(I), 839 format(atom(A0), "~16r", [Abs]), 840 atom_length(A0, L), 841 Rem is L mod 2, 842 hex_pad(Rem, Sign, A0, S). 843 844integer_atomic_sign(I, S) :- 845 Sign is sign(I), 846 sign_atom(Sign, S). 847 848sign_atom(-1, '-'). 849sign_atom( 0, ''). 850sign_atom( 1, ''). 851 852hex_pad(0, Sign, A0, A) :- atom_concat(Sign, A0, A). 853hex_pad(1, Sign, A0, A) :- atomic_list_concat([Sign,'0',A0], A). 854 855pow256(Byte, N0-I0, N-I) :- 856 N is N0 + Byte*256^I0, 857 I is I0 + 1. 858 859hex_to_integer(Hex, N) :- 860 hex_bytes(Hex, Bytes0), 861 reverse(Bytes0, Bytes), 862 foldl(pow256, Bytes, 0-0, N-_). 863 864%% crypto_generate_prime(+N, -P, +Options) is det 865% 866% Generate a prime P with at least N bits. Options is a list of options. 867% Currently, the only supported option is: 868% 869% * safe(Boolean) 870% If `Boolean` is `true` (default is `false`), then a _safe_ prime 871% is generated. This means that P is of the form 2*Q + 1 where Q 872% is also prime. 873 874crypto_generate_prime(Bits, P, Options) :- 875 must_be(list, Options), 876 option(safe(Safe), Options, false), 877 '_crypto_generate_prime'(Bits, Hex, Safe, Options), 878 hex_to_integer(Hex, P). 879 880%% crypto_is_prime(+P, +Options) is semidet 881% 882% True iff P passes a probabilistic primality test. Options is a 883% list of options. Currently, the only supported option is: 884% 885% * iterations(N) 886% N is the number of iterations that are performed. If this option 887% is not specified, a number of iterations is used such that the 888% probability of a false positive is at most 2^(-80). 889 890crypto_is_prime(P0, Options) :- 891 must_be(integer, P0), 892 must_be(list, Options), 893 option(iterations(N), Options, -1), 894 integer_serialized(P0, P), 895 '_crypto_is_prime'(P, N). 896 897%% crypto_name_curve(+Name, -Curve) is det 898% 899% Obtain a handle for a _named_ elliptic curve. Name is an atom, and 900% Curve is unified with an opaque object that represents the curve. 901% Currently, only elliptic curves over prime fields are 902% supported. Examples of such curves are `prime256v1` and 903% `secp256k1`. 904% 905% If you have OpenSSL installed, you can get a list of supported 906% curves via: 907% 908% == 909% $ openssl ecparam -list_curves 910% == 911 912%% crypto_curve_order(+Curve, -Order) is det 913% 914% Obtain the order of an elliptic curve. Order is an integer, 915% denoting how many points on the curve can be reached by 916% multiplying the curve's generator with a scalar. 917 918crypto_curve_order(Curve, Order) :- 919 '_crypto_curve_order'(Curve, Hex), 920 hex_to_integer(Hex, Order). 921 922 923%% crypto_curve_generator(+Curve, -Point) is det 924% 925% Point is the _generator_ of the elliptic curve Curve. 926 927crypto_curve_generator(Curve, point(X,Y)) :- 928 '_crypto_curve_generator'(Curve, X0, Y0), 929 hex_to_integer(X0, X), 930 hex_to_integer(Y0, Y). 931 932%% crypto_curve_scalar_mult(+Curve, +N, +Point, -R) is det 933% 934% R is the result of N times Point on the elliptic curve Curve. N 935% must be an integer, and Point must be a point on the curve. 936 937crypto_curve_scalar_mult(Curve, S0, point(X0,Y0), point(A,B)) :- 938 maplist(integer_serialized, [S0,X0,Y0], [S,X,Y]), 939 '_crypto_curve_scalar_mult'(Curve, S, X, Y, A0, B0), 940 hex_to_integer(A0, A), 941 hex_to_integer(B0, B). 942 943 944 /******************************* 945 * Sandboxing * 946 *******************************/ 947 948:- multifile sandbox:safe_primitive/1. 949 950sandbox:safe_primitive(crypto:hex_bytes(_,_)). 951sandbox:safe_primitive(crypto:crypto_n_random_bytes(_,_)). 952 953sandbox:safe_primitive(crypto:crypto_data_hash(_,_,_)). 954sandbox:safe_primitive(crypto:crypto_data_context(_,_,_)). 955sandbox:safe_primitive(crypto:crypto_context_new(_,_)). 956sandbox:safe_primitive(crypto:crypto_context_hash(_,_)). 957 958sandbox:safe_primitive(crypto:crypto_password_hash(_,_)). 959sandbox:safe_primitive(crypto:crypto_password_hash(_,_,_)). 960sandbox:safe_primitive(crypto:crypto_data_hkdf(_,_,_,_)). 961 962sandbox:safe_primitive(crypto:ecdsa_sign(_,_,_,_)). 963sandbox:safe_primitive(crypto:ecdsa_verify(_,_,_,_)). 964 965sandbox:safe_primitive(crypto:rsa_sign(_,_,_,_)). 966sandbox:safe_primitive(crypto:rsa_verify(_,_,_,_)). 967sandbox:safe_primitive(crypto:rsa_public_encrypt(_,_,_,_)). 968sandbox:safe_primitive(crypto:rsa_public_decrypt(_,_,_,_)). 969sandbox:safe_primitive(crypto:rsa_private_encrypt(_,_,_,_)). 970sandbox:safe_primitive(crypto:rsa_private_decrypt(_,_,_,_)). 971 972sandbox:safe_primitive(crypto:crypto_data_decrypt(_,_,_,_,_,_)). 973sandbox:safe_primitive(crypto:crypto_data_encrypt(_,_,_,_,_,_)). 974 975sandbox:safe_primitive(crypto:crypto_modular_inverse(_,_,_)). 976sandbox:safe_primitive(crypto:crypto_generate_prime(_,_,_)). 977sandbox:safe_primitive(crypto:crypto_is_prime(_,_)). 978 979sandbox:safe_primitive(crypto:crypto_name_curve(_,_)). 980sandbox:safe_primitive(crypto:crypto_curve_order(_,_)). 981sandbox:safe_primitive(crypto:crypto_curve_generator(_,_)). 982sandbox:safe_primitive(crypto:crypto_curve_scalar_mult(_,_,_,_)). 983 984 /******************************* 985 * MESSAGES * 986 *******************************/ 987 988:- multifile 989 prolog:error_message//1. 990 991prologerror_message(ssl_error(ID, _Library, Function, Reason)) --> 992 [ 'SSL(~w) ~w: ~w'-[ID, Function, Reason] ]