2 * ChaCha20-Poly1305 AEAD, RFC7539
4 * Copyright (C) 2015 Martin Willi
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
12 #include <crypto/internal/aead.h>
13 #include <crypto/internal/hash.h>
14 #include <crypto/internal/skcipher.h>
15 #include <crypto/scatterwalk.h>
16 #include <crypto/chacha20.h>
17 #include <crypto/poly1305.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
25 #define CHACHAPOLY_IV_SIZE 12
27 struct chachapoly_instance_ctx {
28 struct crypto_skcipher_spawn chacha;
29 struct crypto_ahash_spawn poly;
33 struct chachapoly_ctx {
34 struct crypto_ablkcipher *chacha;
35 struct crypto_ahash *poly;
36 /* key bytes we use for the ChaCha20 IV */
42 /* zero byte padding for AD/ciphertext, as needed */
43 u8 pad[POLY1305_BLOCK_SIZE];
44 /* tail data with AD/ciphertext lengths */
49 struct scatterlist src[1];
50 struct ahash_request req; /* must be last member */
54 u8 iv[CHACHA20_IV_SIZE];
55 struct scatterlist src[1];
56 struct ablkcipher_request req; /* must be last member */
59 struct chachapoly_req_ctx {
60 struct scatterlist src[2];
61 struct scatterlist dst[2];
62 /* the key we generate for Poly1305 using Chacha20 */
63 u8 key[POLY1305_KEY_SIZE];
64 /* calculated Poly1305 tag */
65 u8 tag[POLY1305_DIGEST_SIZE];
66 /* length of data to en/decrypt, without ICV */
67 unsigned int cryptlen;
68 /* Actual AD, excluding IV */
69 unsigned int assoclen;
72 struct chacha_req chacha;
76 static inline void async_done_continue(struct aead_request *req, int err,
77 int (*cont)(struct aead_request *))
82 if (err != -EINPROGRESS && err != -EBUSY)
83 aead_request_complete(req, err);
86 static void chacha_iv(u8 *iv, struct aead_request *req, u32 icb)
88 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
89 __le32 leicb = cpu_to_le32(icb);
91 memcpy(iv, &leicb, sizeof(leicb));
92 memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen);
93 memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv,
94 CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen);
97 static int poly_verify_tag(struct aead_request *req)
99 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
100 u8 tag[sizeof(rctx->tag)];
102 scatterwalk_map_and_copy(tag, req->src,
103 req->assoclen + rctx->cryptlen,
105 if (crypto_memneq(tag, rctx->tag, sizeof(tag)))
110 static int poly_copy_tag(struct aead_request *req)
112 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
114 scatterwalk_map_and_copy(rctx->tag, req->dst,
115 req->assoclen + rctx->cryptlen,
116 sizeof(rctx->tag), 1);
120 static void chacha_decrypt_done(struct crypto_async_request *areq, int err)
122 async_done_continue(areq->data, err, poly_verify_tag);
125 static int chacha_decrypt(struct aead_request *req)
127 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
128 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
129 struct chacha_req *creq = &rctx->u.chacha;
130 struct scatterlist *src, *dst;
133 chacha_iv(creq->iv, req, 1);
135 sg_init_table(rctx->src, 2);
136 src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
139 if (req->src != req->dst) {
140 sg_init_table(rctx->dst, 2);
141 dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
144 ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
145 chacha_decrypt_done, req);
146 ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
147 ablkcipher_request_set_crypt(&creq->req, src, dst,
148 rctx->cryptlen, creq->iv);
149 err = crypto_ablkcipher_decrypt(&creq->req);
153 return poly_verify_tag(req);
156 static int poly_tail_continue(struct aead_request *req)
158 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
160 if (rctx->cryptlen == req->cryptlen) /* encrypting */
161 return poly_copy_tag(req);
163 return chacha_decrypt(req);
166 static void poly_tail_done(struct crypto_async_request *areq, int err)
168 async_done_continue(areq->data, err, poly_tail_continue);
171 static int poly_tail(struct aead_request *req)
173 struct crypto_aead *tfm = crypto_aead_reqtfm(req);
174 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
175 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
176 struct poly_req *preq = &rctx->u.poly;
180 sg_init_table(preq->src, 1);
181 len = cpu_to_le64(rctx->assoclen);
182 memcpy(&preq->tail.assoclen, &len, sizeof(len));
183 len = cpu_to_le64(rctx->cryptlen);
184 memcpy(&preq->tail.cryptlen, &len, sizeof(len));
185 sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));
187 ahash_request_set_callback(&preq->req, aead_request_flags(req),
188 poly_tail_done, req);
189 ahash_request_set_tfm(&preq->req, ctx->poly);
190 ahash_request_set_crypt(&preq->req, preq->src,
191 rctx->tag, sizeof(preq->tail));
193 err = crypto_ahash_finup(&preq->req);
197 return poly_tail_continue(req);
200 static void poly_cipherpad_done(struct crypto_async_request *areq, int err)
202 async_done_continue(areq->data, err, poly_tail);
205 static int poly_cipherpad(struct aead_request *req)
207 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
208 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
209 struct poly_req *preq = &rctx->u.poly;
210 unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
213 padlen = (bs - (rctx->cryptlen % bs)) % bs;
214 memset(preq->pad, 0, sizeof(preq->pad));
215 sg_init_table(preq->src, 1);
216 sg_set_buf(preq->src, &preq->pad, padlen);
218 ahash_request_set_callback(&preq->req, aead_request_flags(req),
219 poly_cipherpad_done, req);
220 ahash_request_set_tfm(&preq->req, ctx->poly);
221 ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
223 err = crypto_ahash_update(&preq->req);
227 return poly_tail(req);
230 static void poly_cipher_done(struct crypto_async_request *areq, int err)
232 async_done_continue(areq->data, err, poly_cipherpad);
235 static int poly_cipher(struct aead_request *req)
237 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
238 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
239 struct poly_req *preq = &rctx->u.poly;
240 struct scatterlist *crypt = req->src;
243 if (rctx->cryptlen == req->cryptlen) /* encrypting */
246 sg_init_table(rctx->src, 2);
247 crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen);
249 ahash_request_set_callback(&preq->req, aead_request_flags(req),
250 poly_cipher_done, req);
251 ahash_request_set_tfm(&preq->req, ctx->poly);
252 ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
254 err = crypto_ahash_update(&preq->req);
258 return poly_cipherpad(req);
261 static void poly_adpad_done(struct crypto_async_request *areq, int err)
263 async_done_continue(areq->data, err, poly_cipher);
266 static int poly_adpad(struct aead_request *req)
268 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
269 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
270 struct poly_req *preq = &rctx->u.poly;
271 unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
274 padlen = (bs - (rctx->assoclen % bs)) % bs;
275 memset(preq->pad, 0, sizeof(preq->pad));
276 sg_init_table(preq->src, 1);
277 sg_set_buf(preq->src, preq->pad, padlen);
279 ahash_request_set_callback(&preq->req, aead_request_flags(req),
280 poly_adpad_done, req);
281 ahash_request_set_tfm(&preq->req, ctx->poly);
282 ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
284 err = crypto_ahash_update(&preq->req);
288 return poly_cipher(req);
291 static void poly_ad_done(struct crypto_async_request *areq, int err)
293 async_done_continue(areq->data, err, poly_adpad);
296 static int poly_ad(struct aead_request *req)
298 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
299 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
300 struct poly_req *preq = &rctx->u.poly;
303 ahash_request_set_callback(&preq->req, aead_request_flags(req),
305 ahash_request_set_tfm(&preq->req, ctx->poly);
306 ahash_request_set_crypt(&preq->req, req->src, NULL, rctx->assoclen);
308 err = crypto_ahash_update(&preq->req);
312 return poly_adpad(req);
315 static void poly_setkey_done(struct crypto_async_request *areq, int err)
317 async_done_continue(areq->data, err, poly_ad);
320 static int poly_setkey(struct aead_request *req)
322 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
323 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
324 struct poly_req *preq = &rctx->u.poly;
327 sg_init_table(preq->src, 1);
328 sg_set_buf(preq->src, rctx->key, sizeof(rctx->key));
330 ahash_request_set_callback(&preq->req, aead_request_flags(req),
331 poly_setkey_done, req);
332 ahash_request_set_tfm(&preq->req, ctx->poly);
333 ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key));
335 err = crypto_ahash_update(&preq->req);
342 static void poly_init_done(struct crypto_async_request *areq, int err)
344 async_done_continue(areq->data, err, poly_setkey);
347 static int poly_init(struct aead_request *req)
349 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
350 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
351 struct poly_req *preq = &rctx->u.poly;
354 ahash_request_set_callback(&preq->req, aead_request_flags(req),
355 poly_init_done, req);
356 ahash_request_set_tfm(&preq->req, ctx->poly);
358 err = crypto_ahash_init(&preq->req);
362 return poly_setkey(req);
365 static void poly_genkey_done(struct crypto_async_request *areq, int err)
367 async_done_continue(areq->data, err, poly_init);
370 static int poly_genkey(struct aead_request *req)
372 struct crypto_aead *tfm = crypto_aead_reqtfm(req);
373 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
374 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
375 struct chacha_req *creq = &rctx->u.chacha;
378 rctx->assoclen = req->assoclen;
380 if (crypto_aead_ivsize(tfm) == 8) {
381 if (rctx->assoclen < 8)
386 sg_init_table(creq->src, 1);
387 memset(rctx->key, 0, sizeof(rctx->key));
388 sg_set_buf(creq->src, rctx->key, sizeof(rctx->key));
390 chacha_iv(creq->iv, req, 0);
392 ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
393 poly_genkey_done, req);
394 ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
395 ablkcipher_request_set_crypt(&creq->req, creq->src, creq->src,
396 POLY1305_KEY_SIZE, creq->iv);
398 err = crypto_ablkcipher_decrypt(&creq->req);
402 return poly_init(req);
405 static void chacha_encrypt_done(struct crypto_async_request *areq, int err)
407 async_done_continue(areq->data, err, poly_genkey);
410 static int chacha_encrypt(struct aead_request *req)
412 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
413 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
414 struct chacha_req *creq = &rctx->u.chacha;
415 struct scatterlist *src, *dst;
418 chacha_iv(creq->iv, req, 1);
420 sg_init_table(rctx->src, 2);
421 src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
424 if (req->src != req->dst) {
425 sg_init_table(rctx->dst, 2);
426 dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
429 ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
430 chacha_encrypt_done, req);
431 ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
432 ablkcipher_request_set_crypt(&creq->req, src, dst,
433 req->cryptlen, creq->iv);
434 err = crypto_ablkcipher_encrypt(&creq->req);
438 return poly_genkey(req);
441 static int chachapoly_encrypt(struct aead_request *req)
443 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
445 rctx->cryptlen = req->cryptlen;
447 /* encrypt call chain:
448 * - chacha_encrypt/done()
449 * - poly_genkey/done()
451 * - poly_setkey/done()
453 * - poly_adpad/done()
454 * - poly_cipher/done()
455 * - poly_cipherpad/done()
456 * - poly_tail/done/continue()
459 return chacha_encrypt(req);
462 static int chachapoly_decrypt(struct aead_request *req)
464 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
466 rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
468 /* decrypt call chain:
469 * - poly_genkey/done()
471 * - poly_setkey/done()
473 * - poly_adpad/done()
474 * - poly_cipher/done()
475 * - poly_cipherpad/done()
476 * - poly_tail/done/continue()
477 * - chacha_decrypt/done()
478 * - poly_verify_tag()
480 return poly_genkey(req);
483 static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key,
486 struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
489 if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
492 keylen -= ctx->saltlen;
493 memcpy(ctx->salt, key + keylen, ctx->saltlen);
495 crypto_ablkcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK);
496 crypto_ablkcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) &
497 CRYPTO_TFM_REQ_MASK);
499 err = crypto_ablkcipher_setkey(ctx->chacha, key, keylen);
500 crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctx->chacha) &
501 CRYPTO_TFM_RES_MASK);
505 static int chachapoly_setauthsize(struct crypto_aead *tfm,
506 unsigned int authsize)
508 if (authsize != POLY1305_DIGEST_SIZE)
514 static int chachapoly_init(struct crypto_aead *tfm)
516 struct aead_instance *inst = aead_alg_instance(tfm);
517 struct chachapoly_instance_ctx *ictx = aead_instance_ctx(inst);
518 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
519 struct crypto_ablkcipher *chacha;
520 struct crypto_ahash *poly;
523 poly = crypto_spawn_ahash(&ictx->poly);
525 return PTR_ERR(poly);
527 chacha = crypto_spawn_skcipher(&ictx->chacha);
528 if (IS_ERR(chacha)) {
529 crypto_free_ahash(poly);
530 return PTR_ERR(chacha);
533 ctx->chacha = chacha;
535 ctx->saltlen = ictx->saltlen;
537 align = crypto_aead_alignmask(tfm);
538 align &= ~(crypto_tfm_ctx_alignment() - 1);
539 crypto_aead_set_reqsize(
541 align + offsetof(struct chachapoly_req_ctx, u) +
542 max(offsetof(struct chacha_req, req) +
543 sizeof(struct ablkcipher_request) +
544 crypto_ablkcipher_reqsize(chacha),
545 offsetof(struct poly_req, req) +
546 sizeof(struct ahash_request) +
547 crypto_ahash_reqsize(poly)));
552 static void chachapoly_exit(struct crypto_aead *tfm)
554 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
556 crypto_free_ahash(ctx->poly);
557 crypto_free_ablkcipher(ctx->chacha);
560 static void chachapoly_free(struct aead_instance *inst)
562 struct chachapoly_instance_ctx *ctx = aead_instance_ctx(inst);
564 crypto_drop_skcipher(&ctx->chacha);
565 crypto_drop_ahash(&ctx->poly);
569 static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
570 const char *name, unsigned int ivsize)
572 struct crypto_attr_type *algt;
573 struct aead_instance *inst;
574 struct crypto_alg *chacha;
575 struct crypto_alg *poly;
576 struct hash_alg_common *poly_hash;
577 struct chachapoly_instance_ctx *ctx;
578 const char *chacha_name, *poly_name;
581 if (ivsize > CHACHAPOLY_IV_SIZE)
584 algt = crypto_get_attr_type(tb);
586 return PTR_ERR(algt);
588 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
591 chacha_name = crypto_attr_alg_name(tb[1]);
592 if (IS_ERR(chacha_name))
593 return PTR_ERR(chacha_name);
594 poly_name = crypto_attr_alg_name(tb[2]);
595 if (IS_ERR(poly_name))
596 return PTR_ERR(poly_name);
598 poly = crypto_find_alg(poly_name, &crypto_ahash_type,
599 CRYPTO_ALG_TYPE_HASH,
600 CRYPTO_ALG_TYPE_AHASH_MASK);
602 return PTR_ERR(poly);
605 inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
609 ctx = aead_instance_ctx(inst);
610 ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;
611 poly_hash = __crypto_hash_alg_common(poly);
612 err = crypto_init_ahash_spawn(&ctx->poly, poly_hash,
613 aead_crypto_instance(inst));
617 crypto_set_skcipher_spawn(&ctx->chacha, aead_crypto_instance(inst));
618 err = crypto_grab_skcipher(&ctx->chacha, chacha_name, 0,
619 crypto_requires_sync(algt->type,
624 chacha = crypto_skcipher_spawn_alg(&ctx->chacha);
627 /* Need 16-byte IV size, including Initial Block Counter value */
628 if (chacha->cra_ablkcipher.ivsize != CHACHA20_IV_SIZE)
629 goto out_drop_chacha;
630 /* Not a stream cipher? */
631 if (chacha->cra_blocksize != 1)
632 goto out_drop_chacha;
635 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
636 "%s(%s,%s)", name, chacha_name,
637 poly_name) >= CRYPTO_MAX_ALG_NAME)
638 goto out_drop_chacha;
639 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
640 "%s(%s,%s)", name, chacha->cra_driver_name,
641 poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
642 goto out_drop_chacha;
644 inst->alg.base.cra_flags = (chacha->cra_flags | poly->cra_flags) &
646 inst->alg.base.cra_priority = (chacha->cra_priority +
647 poly->cra_priority) / 2;
648 inst->alg.base.cra_blocksize = 1;
649 inst->alg.base.cra_alignmask = chacha->cra_alignmask |
651 inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
653 inst->alg.ivsize = ivsize;
654 inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
655 inst->alg.init = chachapoly_init;
656 inst->alg.exit = chachapoly_exit;
657 inst->alg.encrypt = chachapoly_encrypt;
658 inst->alg.decrypt = chachapoly_decrypt;
659 inst->alg.setkey = chachapoly_setkey;
660 inst->alg.setauthsize = chachapoly_setauthsize;
662 inst->free = chachapoly_free;
664 err = aead_register_instance(tmpl, inst);
666 goto out_drop_chacha;
669 crypto_mod_put(poly);
673 crypto_drop_skcipher(&ctx->chacha);
675 crypto_drop_ahash(&ctx->poly);
681 static int rfc7539_create(struct crypto_template *tmpl, struct rtattr **tb)
683 return chachapoly_create(tmpl, tb, "rfc7539", 12);
686 static int rfc7539esp_create(struct crypto_template *tmpl, struct rtattr **tb)
688 return chachapoly_create(tmpl, tb, "rfc7539esp", 8);
691 static struct crypto_template rfc7539_tmpl = {
693 .create = rfc7539_create,
694 .module = THIS_MODULE,
697 static struct crypto_template rfc7539esp_tmpl = {
698 .name = "rfc7539esp",
699 .create = rfc7539esp_create,
700 .module = THIS_MODULE,
703 static int __init chacha20poly1305_module_init(void)
707 err = crypto_register_template(&rfc7539_tmpl);
711 err = crypto_register_template(&rfc7539esp_tmpl);
713 crypto_unregister_template(&rfc7539_tmpl);
718 static void __exit chacha20poly1305_module_exit(void)
720 crypto_unregister_template(&rfc7539esp_tmpl);
721 crypto_unregister_template(&rfc7539_tmpl);
724 module_init(chacha20poly1305_module_init);
725 module_exit(chacha20poly1305_module_exit);
727 MODULE_LICENSE("GPL");
728 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
729 MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD");
730 MODULE_ALIAS_CRYPTO("rfc7539");
731 MODULE_ALIAS_CRYPTO("rfc7539esp");