12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
21ca1b917SEric Biggers /*
3aa762409SEric Biggers * ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539)
41ca1b917SEric Biggers *
51ca1b917SEric Biggers * Copyright (C) 2015 Martin Willi
61ca1b917SEric Biggers * Copyright (C) 2018 Google LLC
71ca1b917SEric Biggers */
81ca1b917SEric Biggers
91ca1b917SEric Biggers #include <asm/unaligned.h>
101ca1b917SEric Biggers #include <crypto/algapi.h>
115fb8ef25SArd Biesheuvel #include <crypto/internal/chacha.h>
121ca1b917SEric Biggers #include <crypto/internal/skcipher.h>
131ca1b917SEric Biggers #include <linux/module.h>
141ca1b917SEric Biggers
chacha_stream_xor(struct skcipher_request * req,const struct chacha_ctx * ctx,const u8 * iv)151ca1b917SEric Biggers static int chacha_stream_xor(struct skcipher_request *req,
16860ab2e5SEric Biggers const struct chacha_ctx *ctx, const u8 *iv)
171ca1b917SEric Biggers {
181ca1b917SEric Biggers struct skcipher_walk walk;
191ca1b917SEric Biggers u32 state[16];
201ca1b917SEric Biggers int err;
211ca1b917SEric Biggers
221ca1b917SEric Biggers err = skcipher_walk_virt(&walk, req, false);
231ca1b917SEric Biggers
2422cf7053SArd Biesheuvel chacha_init_generic(state, ctx->key, iv);
251ca1b917SEric Biggers
261ca1b917SEric Biggers while (walk.nbytes > 0) {
271ca1b917SEric Biggers unsigned int nbytes = walk.nbytes;
281ca1b917SEric Biggers
291ca1b917SEric Biggers if (nbytes < walk.total)
307aceaaefSEric Biggers nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
311ca1b917SEric Biggers
325fb8ef25SArd Biesheuvel chacha_crypt_generic(state, walk.dst.virt.addr,
335fb8ef25SArd Biesheuvel walk.src.virt.addr, nbytes, ctx->nrounds);
341ca1b917SEric Biggers err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
351ca1b917SEric Biggers }
361ca1b917SEric Biggers
371ca1b917SEric Biggers return err;
381ca1b917SEric Biggers }
391ca1b917SEric Biggers
crypto_chacha_crypt(struct skcipher_request * req)4022cf7053SArd Biesheuvel static int crypto_chacha_crypt(struct skcipher_request *req)
411ca1b917SEric Biggers {
421ca1b917SEric Biggers struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
431ca1b917SEric Biggers struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
441ca1b917SEric Biggers
451ca1b917SEric Biggers return chacha_stream_xor(req, ctx, req->iv);
461ca1b917SEric Biggers }
471ca1b917SEric Biggers
crypto_xchacha_crypt(struct skcipher_request * req)4822cf7053SArd Biesheuvel static int crypto_xchacha_crypt(struct skcipher_request *req)
491ca1b917SEric Biggers {
501ca1b917SEric Biggers struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
511ca1b917SEric Biggers struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
521ca1b917SEric Biggers struct chacha_ctx subctx;
531ca1b917SEric Biggers u32 state[16];
541ca1b917SEric Biggers u8 real_iv[16];
551ca1b917SEric Biggers
561ca1b917SEric Biggers /* Compute the subkey given the original key and first 128 nonce bits */
5722cf7053SArd Biesheuvel chacha_init_generic(state, ctx->key, req->iv);
585fb8ef25SArd Biesheuvel hchacha_block_generic(state, subctx.key, ctx->nrounds);
591ca1b917SEric Biggers subctx.nrounds = ctx->nrounds;
601ca1b917SEric Biggers
611ca1b917SEric Biggers /* Build the real IV */
621ca1b917SEric Biggers memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
631ca1b917SEric Biggers memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
641ca1b917SEric Biggers
651ca1b917SEric Biggers /* Generate the stream and XOR it with the data */
661ca1b917SEric Biggers return chacha_stream_xor(req, &subctx, real_iv);
671ca1b917SEric Biggers }
681ca1b917SEric Biggers
691ca1b917SEric Biggers static struct skcipher_alg algs[] = {
701ca1b917SEric Biggers {
711ca1b917SEric Biggers .base.cra_name = "chacha20",
721ca1b917SEric Biggers .base.cra_driver_name = "chacha20-generic",
731ca1b917SEric Biggers .base.cra_priority = 100,
741ca1b917SEric Biggers .base.cra_blocksize = 1,
751ca1b917SEric Biggers .base.cra_ctxsize = sizeof(struct chacha_ctx),
761ca1b917SEric Biggers .base.cra_module = THIS_MODULE,
771ca1b917SEric Biggers
781ca1b917SEric Biggers .min_keysize = CHACHA_KEY_SIZE,
791ca1b917SEric Biggers .max_keysize = CHACHA_KEY_SIZE,
801ca1b917SEric Biggers .ivsize = CHACHA_IV_SIZE,
811ca1b917SEric Biggers .chunksize = CHACHA_BLOCK_SIZE,
82*2043323aSEric Biggers .setkey = chacha20_setkey,
831ca1b917SEric Biggers .encrypt = crypto_chacha_crypt,
841ca1b917SEric Biggers .decrypt = crypto_chacha_crypt,
851ca1b917SEric Biggers }, {
861ca1b917SEric Biggers .base.cra_name = "xchacha20",
871ca1b917SEric Biggers .base.cra_driver_name = "xchacha20-generic",
881ca1b917SEric Biggers .base.cra_priority = 100,
891ca1b917SEric Biggers .base.cra_blocksize = 1,
901ca1b917SEric Biggers .base.cra_ctxsize = sizeof(struct chacha_ctx),
911ca1b917SEric Biggers .base.cra_module = THIS_MODULE,
921ca1b917SEric Biggers
931ca1b917SEric Biggers .min_keysize = CHACHA_KEY_SIZE,
941ca1b917SEric Biggers .max_keysize = CHACHA_KEY_SIZE,
951ca1b917SEric Biggers .ivsize = XCHACHA_IV_SIZE,
961ca1b917SEric Biggers .chunksize = CHACHA_BLOCK_SIZE,
97*2043323aSEric Biggers .setkey = chacha20_setkey,
981ca1b917SEric Biggers .encrypt = crypto_xchacha_crypt,
991ca1b917SEric Biggers .decrypt = crypto_xchacha_crypt,
100aa762409SEric Biggers }, {
101aa762409SEric Biggers .base.cra_name = "xchacha12",
102aa762409SEric Biggers .base.cra_driver_name = "xchacha12-generic",
103aa762409SEric Biggers .base.cra_priority = 100,
104aa762409SEric Biggers .base.cra_blocksize = 1,
105aa762409SEric Biggers .base.cra_ctxsize = sizeof(struct chacha_ctx),
106aa762409SEric Biggers .base.cra_module = THIS_MODULE,
107aa762409SEric Biggers
108aa762409SEric Biggers .min_keysize = CHACHA_KEY_SIZE,
109aa762409SEric Biggers .max_keysize = CHACHA_KEY_SIZE,
110aa762409SEric Biggers .ivsize = XCHACHA_IV_SIZE,
111aa762409SEric Biggers .chunksize = CHACHA_BLOCK_SIZE,
112*2043323aSEric Biggers .setkey = chacha12_setkey,
113aa762409SEric Biggers .encrypt = crypto_xchacha_crypt,
114aa762409SEric Biggers .decrypt = crypto_xchacha_crypt,
1151ca1b917SEric Biggers }
1161ca1b917SEric Biggers };
1171ca1b917SEric Biggers
chacha_generic_mod_init(void)1181ca1b917SEric Biggers static int __init chacha_generic_mod_init(void)
1191ca1b917SEric Biggers {
1201ca1b917SEric Biggers return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
1211ca1b917SEric Biggers }
1221ca1b917SEric Biggers
chacha_generic_mod_fini(void)1231ca1b917SEric Biggers static void __exit chacha_generic_mod_fini(void)
1241ca1b917SEric Biggers {
1251ca1b917SEric Biggers crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
1261ca1b917SEric Biggers }
1271ca1b917SEric Biggers
128c4741b23SEric Biggers subsys_initcall(chacha_generic_mod_init);
1291ca1b917SEric Biggers module_exit(chacha_generic_mod_fini);
1301ca1b917SEric Biggers
1311ca1b917SEric Biggers MODULE_LICENSE("GPL");
1321ca1b917SEric Biggers MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
1331ca1b917SEric Biggers MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)");
1341ca1b917SEric Biggers MODULE_ALIAS_CRYPTO("chacha20");
1351ca1b917SEric Biggers MODULE_ALIAS_CRYPTO("chacha20-generic");
1361ca1b917SEric Biggers MODULE_ALIAS_CRYPTO("xchacha20");
1371ca1b917SEric Biggers MODULE_ALIAS_CRYPTO("xchacha20-generic");
138aa762409SEric Biggers MODULE_ALIAS_CRYPTO("xchacha12");
139aa762409SEric Biggers MODULE_ALIAS_CRYPTO("xchacha12-generic");
140