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_skcipher *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 skcipher_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 if (rctx->cryptlen == 0)
136 chacha_iv(creq->iv, req, 1);
138 sg_init_table(rctx->src, 2);
139 src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
142 if (req->src != req->dst) {
143 sg_init_table(rctx->dst, 2);
144 dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
147 skcipher_request_set_callback(&creq->req, aead_request_flags(req),
148 chacha_decrypt_done, req);
149 skcipher_request_set_tfm(&creq->req, ctx->chacha);
150 skcipher_request_set_crypt(&creq->req, src, dst,
151 rctx->cryptlen, creq->iv);
152 err = crypto_skcipher_decrypt(&creq->req);
157 return poly_verify_tag(req);
160 static int poly_tail_continue(struct aead_request *req)
162 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
164 if (rctx->cryptlen == req->cryptlen) /* encrypting */
165 return poly_copy_tag(req);
167 return chacha_decrypt(req);
170 static void poly_tail_done(struct crypto_async_request *areq, int err)
172 async_done_continue(areq->data, err, poly_tail_continue);
175 static int poly_tail(struct aead_request *req)
177 struct crypto_aead *tfm = crypto_aead_reqtfm(req);
178 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
179 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
180 struct poly_req *preq = &rctx->u.poly;
184 sg_init_table(preq->src, 1);
185 len = cpu_to_le64(rctx->assoclen);
186 memcpy(&preq->tail.assoclen, &len, sizeof(len));
187 len = cpu_to_le64(rctx->cryptlen);
188 memcpy(&preq->tail.cryptlen, &len, sizeof(len));
189 sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));
191 ahash_request_set_callback(&preq->req, aead_request_flags(req),
192 poly_tail_done, req);
193 ahash_request_set_tfm(&preq->req, ctx->poly);
194 ahash_request_set_crypt(&preq->req, preq->src,
195 rctx->tag, sizeof(preq->tail));
197 err = crypto_ahash_finup(&preq->req);
201 return poly_tail_continue(req);
204 static void poly_cipherpad_done(struct crypto_async_request *areq, int err)
206 async_done_continue(areq->data, err, poly_tail);
209 static int poly_cipherpad(struct aead_request *req)
211 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
212 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
213 struct poly_req *preq = &rctx->u.poly;
214 unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
217 padlen = (bs - (rctx->cryptlen % bs)) % bs;
218 memset(preq->pad, 0, sizeof(preq->pad));
219 sg_init_table(preq->src, 1);
220 sg_set_buf(preq->src, &preq->pad, padlen);
222 ahash_request_set_callback(&preq->req, aead_request_flags(req),
223 poly_cipherpad_done, req);
224 ahash_request_set_tfm(&preq->req, ctx->poly);
225 ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
227 err = crypto_ahash_update(&preq->req);
231 return poly_tail(req);
234 static void poly_cipher_done(struct crypto_async_request *areq, int err)
236 async_done_continue(areq->data, err, poly_cipherpad);
239 static int poly_cipher(struct aead_request *req)
241 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
242 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
243 struct poly_req *preq = &rctx->u.poly;
244 struct scatterlist *crypt = req->src;
247 if (rctx->cryptlen == req->cryptlen) /* encrypting */
250 sg_init_table(rctx->src, 2);
251 crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen);
253 ahash_request_set_callback(&preq->req, aead_request_flags(req),
254 poly_cipher_done, req);
255 ahash_request_set_tfm(&preq->req, ctx->poly);
256 ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
258 err = crypto_ahash_update(&preq->req);
262 return poly_cipherpad(req);
265 static void poly_adpad_done(struct crypto_async_request *areq, int err)
267 async_done_continue(areq->data, err, poly_cipher);
270 static int poly_adpad(struct aead_request *req)
272 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
273 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
274 struct poly_req *preq = &rctx->u.poly;
275 unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
278 padlen = (bs - (rctx->assoclen % bs)) % bs;
279 memset(preq->pad, 0, sizeof(preq->pad));
280 sg_init_table(preq->src, 1);
281 sg_set_buf(preq->src, preq->pad, padlen);
283 ahash_request_set_callback(&preq->req, aead_request_flags(req),
284 poly_adpad_done, req);
285 ahash_request_set_tfm(&preq->req, ctx->poly);
286 ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
288 err = crypto_ahash_update(&preq->req);
292 return poly_cipher(req);
295 static void poly_ad_done(struct crypto_async_request *areq, int err)
297 async_done_continue(areq->data, err, poly_adpad);
300 static int poly_ad(struct aead_request *req)
302 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
303 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
304 struct poly_req *preq = &rctx->u.poly;
307 ahash_request_set_callback(&preq->req, aead_request_flags(req),
309 ahash_request_set_tfm(&preq->req, ctx->poly);
310 ahash_request_set_crypt(&preq->req, req->src, NULL, rctx->assoclen);
312 err = crypto_ahash_update(&preq->req);
316 return poly_adpad(req);
319 static void poly_setkey_done(struct crypto_async_request *areq, int err)
321 async_done_continue(areq->data, err, poly_ad);
324 static int poly_setkey(struct aead_request *req)
326 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
327 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
328 struct poly_req *preq = &rctx->u.poly;
331 sg_init_table(preq->src, 1);
332 sg_set_buf(preq->src, rctx->key, sizeof(rctx->key));
334 ahash_request_set_callback(&preq->req, aead_request_flags(req),
335 poly_setkey_done, req);
336 ahash_request_set_tfm(&preq->req, ctx->poly);
337 ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key));
339 err = crypto_ahash_update(&preq->req);
346 static void poly_init_done(struct crypto_async_request *areq, int err)
348 async_done_continue(areq->data, err, poly_setkey);
351 static int poly_init(struct aead_request *req)
353 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
354 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
355 struct poly_req *preq = &rctx->u.poly;
358 ahash_request_set_callback(&preq->req, aead_request_flags(req),
359 poly_init_done, req);
360 ahash_request_set_tfm(&preq->req, ctx->poly);
362 err = crypto_ahash_init(&preq->req);
366 return poly_setkey(req);
369 static void poly_genkey_done(struct crypto_async_request *areq, int err)
371 async_done_continue(areq->data, err, poly_init);
374 static int poly_genkey(struct aead_request *req)
376 struct crypto_aead *tfm = crypto_aead_reqtfm(req);
377 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
378 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
379 struct chacha_req *creq = &rctx->u.chacha;
382 rctx->assoclen = req->assoclen;
384 if (crypto_aead_ivsize(tfm) == 8) {
385 if (rctx->assoclen < 8)
390 sg_init_table(creq->src, 1);
391 memset(rctx->key, 0, sizeof(rctx->key));
392 sg_set_buf(creq->src, rctx->key, sizeof(rctx->key));
394 chacha_iv(creq->iv, req, 0);
396 skcipher_request_set_callback(&creq->req, aead_request_flags(req),
397 poly_genkey_done, req);
398 skcipher_request_set_tfm(&creq->req, ctx->chacha);
399 skcipher_request_set_crypt(&creq->req, creq->src, creq->src,
400 POLY1305_KEY_SIZE, creq->iv);
402 err = crypto_skcipher_decrypt(&creq->req);
406 return poly_init(req);
409 static void chacha_encrypt_done(struct crypto_async_request *areq, int err)
411 async_done_continue(areq->data, err, poly_genkey);
414 static int chacha_encrypt(struct aead_request *req)
416 struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
417 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
418 struct chacha_req *creq = &rctx->u.chacha;
419 struct scatterlist *src, *dst;
422 if (req->cryptlen == 0)
425 chacha_iv(creq->iv, req, 1);
427 sg_init_table(rctx->src, 2);
428 src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
431 if (req->src != req->dst) {
432 sg_init_table(rctx->dst, 2);
433 dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
436 skcipher_request_set_callback(&creq->req, aead_request_flags(req),
437 chacha_encrypt_done, req);
438 skcipher_request_set_tfm(&creq->req, ctx->chacha);
439 skcipher_request_set_crypt(&creq->req, src, dst,
440 req->cryptlen, creq->iv);
441 err = crypto_skcipher_encrypt(&creq->req);
446 return poly_genkey(req);
449 static int chachapoly_encrypt(struct aead_request *req)
451 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
453 rctx->cryptlen = req->cryptlen;
455 /* encrypt call chain:
456 * - chacha_encrypt/done()
457 * - poly_genkey/done()
459 * - poly_setkey/done()
461 * - poly_adpad/done()
462 * - poly_cipher/done()
463 * - poly_cipherpad/done()
464 * - poly_tail/done/continue()
467 return chacha_encrypt(req);
470 static int chachapoly_decrypt(struct aead_request *req)
472 struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
474 rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
476 /* decrypt call chain:
477 * - poly_genkey/done()
479 * - poly_setkey/done()
481 * - poly_adpad/done()
482 * - poly_cipher/done()
483 * - poly_cipherpad/done()
484 * - poly_tail/done/continue()
485 * - chacha_decrypt/done()
486 * - poly_verify_tag()
488 return poly_genkey(req);
491 static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key,
494 struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
497 if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
500 keylen -= ctx->saltlen;
501 memcpy(ctx->salt, key + keylen, ctx->saltlen);
503 crypto_skcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK);
504 crypto_skcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) &
505 CRYPTO_TFM_REQ_MASK);
507 err = crypto_skcipher_setkey(ctx->chacha, key, keylen);
508 crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctx->chacha) &
509 CRYPTO_TFM_RES_MASK);
513 static int chachapoly_setauthsize(struct crypto_aead *tfm,
514 unsigned int authsize)
516 if (authsize != POLY1305_DIGEST_SIZE)
522 static int chachapoly_init(struct crypto_aead *tfm)
524 struct aead_instance *inst = aead_alg_instance(tfm);
525 struct chachapoly_instance_ctx *ictx = aead_instance_ctx(inst);
526 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
527 struct crypto_skcipher *chacha;
528 struct crypto_ahash *poly;
531 poly = crypto_spawn_ahash(&ictx->poly);
533 return PTR_ERR(poly);
535 chacha = crypto_spawn_skcipher2(&ictx->chacha);
536 if (IS_ERR(chacha)) {
537 crypto_free_ahash(poly);
538 return PTR_ERR(chacha);
541 ctx->chacha = chacha;
543 ctx->saltlen = ictx->saltlen;
545 align = crypto_aead_alignmask(tfm);
546 align &= ~(crypto_tfm_ctx_alignment() - 1);
547 crypto_aead_set_reqsize(
549 align + offsetof(struct chachapoly_req_ctx, u) +
550 max(offsetof(struct chacha_req, req) +
551 sizeof(struct skcipher_request) +
552 crypto_skcipher_reqsize(chacha),
553 offsetof(struct poly_req, req) +
554 sizeof(struct ahash_request) +
555 crypto_ahash_reqsize(poly)));
560 static void chachapoly_exit(struct crypto_aead *tfm)
562 struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
564 crypto_free_ahash(ctx->poly);
565 crypto_free_skcipher(ctx->chacha);
568 static void chachapoly_free(struct aead_instance *inst)
570 struct chachapoly_instance_ctx *ctx = aead_instance_ctx(inst);
572 crypto_drop_skcipher(&ctx->chacha);
573 crypto_drop_ahash(&ctx->poly);
577 static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
578 const char *name, unsigned int ivsize)
580 struct crypto_attr_type *algt;
581 struct aead_instance *inst;
582 struct skcipher_alg *chacha;
583 struct crypto_alg *poly;
584 struct hash_alg_common *poly_hash;
585 struct chachapoly_instance_ctx *ctx;
586 const char *chacha_name, *poly_name;
589 if (ivsize > CHACHAPOLY_IV_SIZE)
592 algt = crypto_get_attr_type(tb);
594 return PTR_ERR(algt);
596 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
599 chacha_name = crypto_attr_alg_name(tb[1]);
600 if (IS_ERR(chacha_name))
601 return PTR_ERR(chacha_name);
602 poly_name = crypto_attr_alg_name(tb[2]);
603 if (IS_ERR(poly_name))
604 return PTR_ERR(poly_name);
606 poly = crypto_find_alg(poly_name, &crypto_ahash_type,
607 CRYPTO_ALG_TYPE_HASH,
608 CRYPTO_ALG_TYPE_AHASH_MASK |
609 crypto_requires_sync(algt->type,
612 return PTR_ERR(poly);
615 inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
619 ctx = aead_instance_ctx(inst);
620 ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;
621 poly_hash = __crypto_hash_alg_common(poly);
622 err = crypto_init_ahash_spawn(&ctx->poly, poly_hash,
623 aead_crypto_instance(inst));
627 crypto_set_skcipher_spawn(&ctx->chacha, aead_crypto_instance(inst));
628 err = crypto_grab_skcipher2(&ctx->chacha, chacha_name, 0,
629 crypto_requires_sync(algt->type,
634 chacha = crypto_spawn_skcipher_alg(&ctx->chacha);
637 /* Need 16-byte IV size, including Initial Block Counter value */
638 if (crypto_skcipher_alg_ivsize(chacha) != CHACHA20_IV_SIZE)
639 goto out_drop_chacha;
640 /* Not a stream cipher? */
641 if (chacha->base.cra_blocksize != 1)
642 goto out_drop_chacha;
645 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
646 "%s(%s,%s)", name, chacha_name,
647 poly_name) >= CRYPTO_MAX_ALG_NAME)
648 goto out_drop_chacha;
649 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
650 "%s(%s,%s)", name, chacha->base.cra_driver_name,
651 poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
652 goto out_drop_chacha;
654 inst->alg.base.cra_flags = (chacha->base.cra_flags | poly->cra_flags) &
656 inst->alg.base.cra_priority = (chacha->base.cra_priority +
657 poly->cra_priority) / 2;
658 inst->alg.base.cra_blocksize = 1;
659 inst->alg.base.cra_alignmask = chacha->base.cra_alignmask |
661 inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
663 inst->alg.ivsize = ivsize;
664 inst->alg.chunksize = crypto_skcipher_alg_chunksize(chacha);
665 inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
666 inst->alg.init = chachapoly_init;
667 inst->alg.exit = chachapoly_exit;
668 inst->alg.encrypt = chachapoly_encrypt;
669 inst->alg.decrypt = chachapoly_decrypt;
670 inst->alg.setkey = chachapoly_setkey;
671 inst->alg.setauthsize = chachapoly_setauthsize;
673 inst->free = chachapoly_free;
675 err = aead_register_instance(tmpl, inst);
677 goto out_drop_chacha;
680 crypto_mod_put(poly);
684 crypto_drop_skcipher(&ctx->chacha);
686 crypto_drop_ahash(&ctx->poly);
692 static int rfc7539_create(struct crypto_template *tmpl, struct rtattr **tb)
694 return chachapoly_create(tmpl, tb, "rfc7539", 12);
697 static int rfc7539esp_create(struct crypto_template *tmpl, struct rtattr **tb)
699 return chachapoly_create(tmpl, tb, "rfc7539esp", 8);
702 static struct crypto_template rfc7539_tmpl = {
704 .create = rfc7539_create,
705 .module = THIS_MODULE,
708 static struct crypto_template rfc7539esp_tmpl = {
709 .name = "rfc7539esp",
710 .create = rfc7539esp_create,
711 .module = THIS_MODULE,
714 static int __init chacha20poly1305_module_init(void)
718 err = crypto_register_template(&rfc7539_tmpl);
722 err = crypto_register_template(&rfc7539esp_tmpl);
724 crypto_unregister_template(&rfc7539_tmpl);
729 static void __exit chacha20poly1305_module_exit(void)
731 crypto_unregister_template(&rfc7539esp_tmpl);
732 crypto_unregister_template(&rfc7539_tmpl);
735 module_init(chacha20poly1305_module_init);
736 module_exit(chacha20poly1305_module_exit);
738 MODULE_LICENSE("GPL");
739 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
740 MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD");
741 MODULE_ALIAS_CRYPTO("rfc7539");
742 MODULE_ALIAS_CRYPTO("rfc7539esp");