crypto: chacha20poly1305 - Add a ChaCha20-Poly1305 AEAD construction, RFC7539
authorMartin Willi <martin@strongswan.org>
Mon, 1 Jun 2015 11:44:00 +0000 (13:44 +0200)
committerHerbert Xu <herbert@gondor.apana.org.au>
Thu, 4 Jun 2015 07:04:52 +0000 (15:04 +0800)
This AEAD uses a chacha20 ablkcipher and a poly1305 ahash to construct the
ChaCha20-Poly1305 AEAD as defined in RFC7539. It supports both synchronous and
asynchronous operations, even if we currently have no async chacha20 or poly1305
drivers.

Signed-off-by: Martin Willi <martin@strongswan.org>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
crypto/Kconfig
crypto/Makefile
crypto/chacha20poly1305.c [new file with mode: 0644]

index 9c00454ed0248590880dd3780240ae626a4929ce..1bc7e0b85b5dd3622e7ce971b408b0a4898be0ea 100644 (file)
@@ -217,6 +217,18 @@ config CRYPTO_GCM
          Support for Galois/Counter Mode (GCM) and Galois Message
          Authentication Code (GMAC). Required for IPSec.
 
+config CRYPTO_CHACHA20POLY1305
+       tristate "ChaCha20-Poly1305 AEAD support"
+       select CRYPTO_CHACHA20
+       select CRYPTO_POLY1305
+       select CRYPTO_AEAD
+       help
+         ChaCha20-Poly1305 AEAD support, RFC7539.
+
+         Support for the AEAD wrapper using the ChaCha20 stream cipher combined
+         with the Poly1305 authenticator. It is defined in RFC7539 for use in
+         IETF protocols.
+
 config CRYPTO_SEQIV
        tristate "Sequence Number IV Generator"
        select CRYPTO_AEAD
index 2424c81d69bc6018cf4f76006ee2ce1a5c4f0065..e6cf6a5426abb4a798f3f387d34c6bf4229e66af 100644 (file)
@@ -59,6 +59,7 @@ obj-$(CONFIG_CRYPTO_XTS) += xts.o
 obj-$(CONFIG_CRYPTO_CTR) += ctr.o
 obj-$(CONFIG_CRYPTO_GCM) += gcm.o
 obj-$(CONFIG_CRYPTO_CCM) += ccm.o
+obj-$(CONFIG_CRYPTO_CHACHA20POLY1305) += chacha20poly1305.o
 obj-$(CONFIG_CRYPTO_PCRYPT) += pcrypt.o
 obj-$(CONFIG_CRYPTO_CRYPTD) += cryptd.o
 obj-$(CONFIG_CRYPTO_MCRYPTD) += mcryptd.o
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c
new file mode 100644 (file)
index 0000000..6171cf1
--- /dev/null
@@ -0,0 +1,663 @@
+/*
+ * ChaCha20-Poly1305 AEAD, RFC7539
+ *
+ * Copyright (C) 2015 Martin Willi
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <crypto/internal/aead.h>
+#include <crypto/internal/hash.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "internal.h"
+
+#define POLY1305_BLOCK_SIZE    16
+#define POLY1305_DIGEST_SIZE   16
+#define POLY1305_KEY_SIZE      32
+#define CHACHA20_KEY_SIZE      32
+#define CHACHA20_IV_SIZE       16
+#define CHACHAPOLY_IV_SIZE     12
+
+struct chachapoly_instance_ctx {
+       struct crypto_skcipher_spawn chacha;
+       struct crypto_ahash_spawn poly;
+       unsigned int saltlen;
+};
+
+struct chachapoly_ctx {
+       struct crypto_ablkcipher *chacha;
+       struct crypto_ahash *poly;
+       /* key bytes we use for the ChaCha20 IV */
+       unsigned int saltlen;
+       u8 salt[];
+};
+
+struct poly_req {
+       /* zero byte padding for AD/ciphertext, as needed */
+       u8 pad[POLY1305_BLOCK_SIZE];
+       /* tail data with AD/ciphertext lengths */
+       struct {
+               __le64 assoclen;
+               __le64 cryptlen;
+       } tail;
+       struct scatterlist src[1];
+       struct ahash_request req; /* must be last member */
+};
+
+struct chacha_req {
+       /* the key we generate for Poly1305 using Chacha20 */
+       u8 key[POLY1305_KEY_SIZE];
+       u8 iv[CHACHA20_IV_SIZE];
+       struct scatterlist src[1];
+       struct ablkcipher_request req; /* must be last member */
+};
+
+struct chachapoly_req_ctx {
+       /* calculated Poly1305 tag */
+       u8 tag[POLY1305_DIGEST_SIZE];
+       /* length of data to en/decrypt, without ICV */
+       unsigned int cryptlen;
+       union {
+               struct poly_req poly;
+               struct chacha_req chacha;
+       } u;
+};
+
+static inline void async_done_continue(struct aead_request *req, int err,
+                                      int (*cont)(struct aead_request *))
+{
+       if (!err)
+               err = cont(req);
+
+       if (err != -EINPROGRESS && err != -EBUSY)
+               aead_request_complete(req, err);
+}
+
+static void chacha_iv(u8 *iv, struct aead_request *req, u32 icb)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       __le32 leicb = cpu_to_le32(icb);
+
+       memcpy(iv, &leicb, sizeof(leicb));
+       memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen);
+       memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv,
+              CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen);
+}
+
+static int poly_verify_tag(struct aead_request *req)
+{
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       u8 tag[sizeof(rctx->tag)];
+
+       scatterwalk_map_and_copy(tag, req->src, rctx->cryptlen, sizeof(tag), 0);
+       if (crypto_memneq(tag, rctx->tag, sizeof(tag)))
+               return -EBADMSG;
+       return 0;
+}
+
+static int poly_copy_tag(struct aead_request *req)
+{
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+
+       scatterwalk_map_and_copy(rctx->tag, req->dst, rctx->cryptlen,
+                                sizeof(rctx->tag), 1);
+       return 0;
+}
+
+static void chacha_decrypt_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_verify_tag);
+}
+
+static int chacha_decrypt(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct chacha_req *creq = &rctx->u.chacha;
+       int err;
+
+       chacha_iv(creq->iv, req, 1);
+
+       ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
+                                       chacha_decrypt_done, req);
+       ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
+       ablkcipher_request_set_crypt(&creq->req, req->src, req->dst,
+                                    rctx->cryptlen, creq->iv);
+       err = crypto_ablkcipher_decrypt(&creq->req);
+       if (err)
+               return err;
+
+       return poly_verify_tag(req);
+}
+
+static int poly_tail_continue(struct aead_request *req)
+{
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+
+       if (rctx->cryptlen == req->cryptlen) /* encrypting */
+               return poly_copy_tag(req);
+
+       return chacha_decrypt(req);
+}
+
+static void poly_tail_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_tail_continue);
+}
+
+static int poly_tail(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       __le64 len;
+       int err;
+
+       sg_init_table(preq->src, 1);
+       len = cpu_to_le64(req->assoclen);
+       memcpy(&preq->tail.assoclen, &len, sizeof(len));
+       len = cpu_to_le64(rctx->cryptlen);
+       memcpy(&preq->tail.cryptlen, &len, sizeof(len));
+       sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_tail_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+       ahash_request_set_crypt(&preq->req, preq->src,
+                               rctx->tag, sizeof(preq->tail));
+
+       err = crypto_ahash_finup(&preq->req);
+       if (err)
+               return err;
+
+       return poly_tail_continue(req);
+}
+
+static void poly_cipherpad_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_tail);
+}
+
+static int poly_cipherpad(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
+       int err;
+
+       padlen = (bs - (rctx->cryptlen % bs)) % bs;
+       memset(preq->pad, 0, sizeof(preq->pad));
+       sg_init_table(preq->src, 1);
+       sg_set_buf(preq->src, &preq->pad, padlen);
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_cipherpad_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+       ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
+
+       err = crypto_ahash_update(&preq->req);
+       if (err)
+               return err;
+
+       return poly_tail(req);
+}
+
+static void poly_cipher_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_cipherpad);
+}
+
+static int poly_cipher(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       struct scatterlist *crypt = req->src;
+       int err;
+
+       if (rctx->cryptlen == req->cryptlen) /* encrypting */
+               crypt = req->dst;
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_cipher_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+       ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
+
+       err = crypto_ahash_update(&preq->req);
+       if (err)
+               return err;
+
+       return poly_cipherpad(req);
+}
+
+static void poly_adpad_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_cipher);
+}
+
+static int poly_adpad(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
+       int err;
+
+       padlen = (bs - (req->assoclen % bs)) % bs;
+       memset(preq->pad, 0, sizeof(preq->pad));
+       sg_init_table(preq->src, 1);
+       sg_set_buf(preq->src, preq->pad, padlen);
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_adpad_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+       ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
+
+       err = crypto_ahash_update(&preq->req);
+       if (err)
+               return err;
+
+       return poly_cipher(req);
+}
+
+static void poly_ad_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_adpad);
+}
+
+static int poly_ad(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       int err;
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_ad_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+       ahash_request_set_crypt(&preq->req, req->assoc, NULL, req->assoclen);
+
+       err = crypto_ahash_update(&preq->req);
+       if (err)
+               return err;
+
+       return poly_adpad(req);
+}
+
+static void poly_init_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_ad);
+}
+
+static int poly_init(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct poly_req *preq = &rctx->u.poly;
+       int err;
+
+       ahash_request_set_callback(&preq->req, aead_request_flags(req),
+                                  poly_init_done, req);
+       ahash_request_set_tfm(&preq->req, ctx->poly);
+
+       err = crypto_ahash_init(&preq->req);
+       if (err)
+               return err;
+
+       return poly_ad(req);
+}
+
+static int poly_genkey_continue(struct aead_request *req)
+{
+       struct crypto_aead *aead = crypto_aead_reqtfm(req);
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct chacha_req *creq = &rctx->u.chacha;
+       int err;
+
+       crypto_ahash_clear_flags(ctx->poly, CRYPTO_TFM_REQ_MASK);
+       crypto_ahash_set_flags(ctx->poly, crypto_aead_get_flags(aead) &
+                              CRYPTO_TFM_REQ_MASK);
+
+       err = crypto_ahash_setkey(ctx->poly, creq->key, sizeof(creq->key));
+       crypto_aead_set_flags(aead, crypto_ahash_get_flags(ctx->poly) &
+                             CRYPTO_TFM_RES_MASK);
+       if (err)
+               return err;
+
+       return poly_init(req);
+}
+
+static void poly_genkey_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_genkey_continue);
+}
+
+static int poly_genkey(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct chacha_req *creq = &rctx->u.chacha;
+       int err;
+
+       sg_init_table(creq->src, 1);
+       memset(creq->key, 0, sizeof(creq->key));
+       sg_set_buf(creq->src, creq->key, sizeof(creq->key));
+
+       chacha_iv(creq->iv, req, 0);
+
+       ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
+                                       poly_genkey_done, req);
+       ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
+       ablkcipher_request_set_crypt(&creq->req, creq->src, creq->src,
+                                    POLY1305_KEY_SIZE, creq->iv);
+
+       err = crypto_ablkcipher_decrypt(&creq->req);
+       if (err)
+               return err;
+
+       return poly_genkey_continue(req);
+}
+
+static void chacha_encrypt_done(struct crypto_async_request *areq, int err)
+{
+       async_done_continue(areq->data, err, poly_genkey);
+}
+
+static int chacha_encrypt(struct aead_request *req)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+       struct chacha_req *creq = &rctx->u.chacha;
+       int err;
+
+       chacha_iv(creq->iv, req, 1);
+
+       ablkcipher_request_set_callback(&creq->req, aead_request_flags(req),
+                                       chacha_encrypt_done, req);
+       ablkcipher_request_set_tfm(&creq->req, ctx->chacha);
+       ablkcipher_request_set_crypt(&creq->req, req->src, req->dst,
+                                    req->cryptlen, creq->iv);
+       err = crypto_ablkcipher_encrypt(&creq->req);
+       if (err)
+               return err;
+
+       return poly_genkey(req);
+}
+
+static int chachapoly_encrypt(struct aead_request *req)
+{
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+
+       rctx->cryptlen = req->cryptlen;
+
+       /* encrypt call chain:
+        * - chacha_encrypt/done()
+        * - poly_genkey/done/continue()
+        * - poly_init/done()
+        * - poly_ad/done()
+        * - poly_adpad/done()
+        * - poly_cipher/done()
+        * - poly_cipherpad/done()
+        * - poly_tail/done/continue()
+        * - poly_copy_tag()
+        */
+       return chacha_encrypt(req);
+}
+
+static int chachapoly_decrypt(struct aead_request *req)
+{
+       struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+
+       if (req->cryptlen < POLY1305_DIGEST_SIZE)
+               return -EINVAL;
+       rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
+
+       /* decrypt call chain:
+        * - poly_genkey/done/continue()
+        * - poly_init/done()
+        * - poly_ad/done()
+        * - poly_adpad/done()
+        * - poly_cipher/done()
+        * - poly_cipherpad/done()
+        * - poly_tail/done/continue()
+        * - chacha_decrypt/done()
+        * - poly_verify_tag()
+        */
+       return poly_genkey(req);
+}
+
+static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key,
+                            unsigned int keylen)
+{
+       struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
+       int err;
+
+       if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
+               return -EINVAL;
+
+       keylen -= ctx->saltlen;
+       memcpy(ctx->salt, key + keylen, ctx->saltlen);
+
+       crypto_ablkcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK);
+       crypto_ablkcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) &
+                                   CRYPTO_TFM_REQ_MASK);
+
+       err = crypto_ablkcipher_setkey(ctx->chacha, key, keylen);
+       crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctx->chacha) &
+                             CRYPTO_TFM_RES_MASK);
+       return err;
+}
+
+static int chachapoly_setauthsize(struct crypto_aead *tfm,
+                                 unsigned int authsize)
+{
+       if (authsize != POLY1305_DIGEST_SIZE)
+               return -EINVAL;
+
+       return 0;
+}
+
+static int chachapoly_init(struct crypto_tfm *tfm)
+{
+       struct crypto_instance *inst = (void *)tfm->__crt_alg;
+       struct chachapoly_instance_ctx *ictx = crypto_instance_ctx(inst);
+       struct chachapoly_ctx *ctx = crypto_tfm_ctx(tfm);
+       struct crypto_ablkcipher *chacha;
+       struct crypto_ahash *poly;
+       unsigned long align;
+
+       poly = crypto_spawn_ahash(&ictx->poly);
+       if (IS_ERR(poly))
+               return PTR_ERR(poly);
+
+       chacha = crypto_spawn_skcipher(&ictx->chacha);
+       if (IS_ERR(chacha)) {
+               crypto_free_ahash(poly);
+               return PTR_ERR(chacha);
+       }
+
+       ctx->chacha = chacha;
+       ctx->poly = poly;
+       ctx->saltlen = ictx->saltlen;
+
+       align = crypto_tfm_alg_alignmask(tfm);
+       align &= ~(crypto_tfm_ctx_alignment() - 1);
+       crypto_aead_set_reqsize(__crypto_aead_cast(tfm),
+                               align + offsetof(struct chachapoly_req_ctx, u) +
+                               max(offsetof(struct chacha_req, req) +
+                                   sizeof(struct ablkcipher_request) +
+                                   crypto_ablkcipher_reqsize(chacha),
+                                   offsetof(struct poly_req, req) +
+                                   sizeof(struct ahash_request) +
+                                   crypto_ahash_reqsize(poly)));
+
+       return 0;
+}
+
+static void chachapoly_exit(struct crypto_tfm *tfm)
+{
+       struct chachapoly_ctx *ctx = crypto_tfm_ctx(tfm);
+
+       crypto_free_ahash(ctx->poly);
+       crypto_free_ablkcipher(ctx->chacha);
+}
+
+static struct crypto_instance *chachapoly_alloc(struct rtattr **tb,
+                                               const char *name,
+                                               unsigned int ivsize)
+{
+       struct crypto_attr_type *algt;
+       struct crypto_instance *inst;
+       struct crypto_alg *chacha;
+       struct crypto_alg *poly;
+       struct ahash_alg *poly_ahash;
+       struct chachapoly_instance_ctx *ctx;
+       const char *chacha_name, *poly_name;
+       int err;
+
+       if (ivsize > CHACHAPOLY_IV_SIZE)
+               return ERR_PTR(-EINVAL);
+
+       algt = crypto_get_attr_type(tb);
+       if (IS_ERR(algt))
+               return ERR_CAST(algt);
+
+       if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
+               return ERR_PTR(-EINVAL);
+
+       chacha_name = crypto_attr_alg_name(tb[1]);
+       if (IS_ERR(chacha_name))
+               return ERR_CAST(chacha_name);
+       poly_name = crypto_attr_alg_name(tb[2]);
+       if (IS_ERR(poly_name))
+               return ERR_CAST(poly_name);
+
+       poly = crypto_find_alg(poly_name, &crypto_ahash_type,
+                              CRYPTO_ALG_TYPE_HASH,
+                              CRYPTO_ALG_TYPE_AHASH_MASK);
+       if (IS_ERR(poly))
+               return ERR_CAST(poly);
+
+       err = -ENOMEM;
+       inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+       if (!inst)
+               goto out_put_poly;
+
+       ctx = crypto_instance_ctx(inst);
+       ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;
+       poly_ahash = container_of(poly, struct ahash_alg, halg.base);
+       err = crypto_init_ahash_spawn(&ctx->poly, &poly_ahash->halg, inst);
+       if (err)
+               goto err_free_inst;
+
+       crypto_set_skcipher_spawn(&ctx->chacha, inst);
+       err = crypto_grab_skcipher(&ctx->chacha, chacha_name, 0,
+                                  crypto_requires_sync(algt->type,
+                                                       algt->mask));
+       if (err)
+               goto err_drop_poly;
+
+       chacha = crypto_skcipher_spawn_alg(&ctx->chacha);
+
+       err = -EINVAL;
+       /* Need 16-byte IV size, including Initial Block Counter value */
+       if (chacha->cra_ablkcipher.ivsize != CHACHA20_IV_SIZE)
+               goto out_drop_chacha;
+       /* Not a stream cipher? */
+       if (chacha->cra_blocksize != 1)
+               goto out_drop_chacha;
+
+       err = -ENAMETOOLONG;
+       if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+                    "%s(%s,%s)", name, chacha_name,
+                    poly_name) >= CRYPTO_MAX_ALG_NAME)
+               goto out_drop_chacha;
+       if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+                    "%s(%s,%s)", name, chacha->cra_driver_name,
+                    poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+               goto out_drop_chacha;
+
+       inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
+       inst->alg.cra_flags |= (chacha->cra_flags |
+                               poly->cra_flags) & CRYPTO_ALG_ASYNC;
+       inst->alg.cra_priority = (chacha->cra_priority +
+                                 poly->cra_priority) / 2;
+       inst->alg.cra_blocksize = 1;
+       inst->alg.cra_alignmask = chacha->cra_alignmask | poly->cra_alignmask;
+       inst->alg.cra_type = &crypto_nivaead_type;
+       inst->alg.cra_aead.ivsize = ivsize;
+       inst->alg.cra_aead.maxauthsize = POLY1305_DIGEST_SIZE;
+       inst->alg.cra_ctxsize = sizeof(struct chachapoly_ctx) + ctx->saltlen;
+       inst->alg.cra_init = chachapoly_init;
+       inst->alg.cra_exit = chachapoly_exit;
+       inst->alg.cra_aead.encrypt = chachapoly_encrypt;
+       inst->alg.cra_aead.decrypt = chachapoly_decrypt;
+       inst->alg.cra_aead.setkey = chachapoly_setkey;
+       inst->alg.cra_aead.setauthsize = chachapoly_setauthsize;
+       inst->alg.cra_aead.geniv = "seqiv";
+
+out:
+       crypto_mod_put(poly);
+       return inst;
+
+out_drop_chacha:
+       crypto_drop_skcipher(&ctx->chacha);
+err_drop_poly:
+       crypto_drop_ahash(&ctx->poly);
+err_free_inst:
+       kfree(inst);
+out_put_poly:
+       inst = ERR_PTR(err);
+       goto out;
+}
+
+static struct crypto_instance *rfc7539_alloc(struct rtattr **tb)
+{
+       return chachapoly_alloc(tb, "rfc7539", 12);
+}
+
+static void chachapoly_free(struct crypto_instance *inst)
+{
+       struct chachapoly_instance_ctx *ctx = crypto_instance_ctx(inst);
+
+       crypto_drop_skcipher(&ctx->chacha);
+       crypto_drop_ahash(&ctx->poly);
+       kfree(inst);
+}
+
+static struct crypto_template rfc7539_tmpl = {
+       .name = "rfc7539",
+       .alloc = rfc7539_alloc,
+       .free = chachapoly_free,
+       .module = THIS_MODULE,
+};
+
+static int __init chacha20poly1305_module_init(void)
+{
+       return crypto_register_template(&rfc7539_tmpl);
+}
+
+static void __exit chacha20poly1305_module_exit(void)
+{
+       crypto_unregister_template(&rfc7539_tmpl);
+}
+
+module_init(chacha20poly1305_module_init);
+module_exit(chacha20poly1305_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
+MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD");
+MODULE_ALIAS_CRYPTO("chacha20poly1305");
+MODULE_ALIAS_CRYPTO("rfc7539");