diff options
Diffstat (limited to 'crypto/chacha20_generic.c')
| -rw-r--r-- | crypto/chacha20_generic.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c new file mode 100644 index 000000000..3ae96587c --- /dev/null +++ b/crypto/chacha20_generic.c @@ -0,0 +1,137 @@ +/* + * ChaCha20 256-bit cipher algorithm, 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 <asm/unaligned.h> +#include <crypto/algapi.h> +#include <crypto/chacha20.h> +#include <crypto/internal/skcipher.h> +#include <linux/module.h> + +static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes) +{ + /* aligned to potentially speed up crypto_xor() */ + u8 stream[CHACHA20_BLOCK_SIZE] __aligned(sizeof(long)); + + if (dst != src) + memcpy(dst, src, bytes); + + while (bytes >= CHACHA20_BLOCK_SIZE) { + chacha20_block(state, stream); + crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE); + bytes -= CHACHA20_BLOCK_SIZE; + dst += CHACHA20_BLOCK_SIZE; + } + if (bytes) { + chacha20_block(state, stream); + crypto_xor(dst, stream, bytes); + } +} + +void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv) +{ + state[0] = 0x61707865; /* "expa" */ + state[1] = 0x3320646e; /* "nd 3" */ + state[2] = 0x79622d32; /* "2-by" */ + state[3] = 0x6b206574; /* "te k" */ + state[4] = ctx->key[0]; + state[5] = ctx->key[1]; + state[6] = ctx->key[2]; + state[7] = ctx->key[3]; + state[8] = ctx->key[4]; + state[9] = ctx->key[5]; + state[10] = ctx->key[6]; + state[11] = ctx->key[7]; + state[12] = get_unaligned_le32(iv + 0); + state[13] = get_unaligned_le32(iv + 4); + state[14] = get_unaligned_le32(iv + 8); + state[15] = get_unaligned_le32(iv + 12); +} +EXPORT_SYMBOL_GPL(crypto_chacha20_init); + +int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, + unsigned int keysize) +{ + struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm); + int i; + + if (keysize != CHACHA20_KEY_SIZE) + return -EINVAL; + + for (i = 0; i < ARRAY_SIZE(ctx->key); i++) + ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32)); + + return 0; +} +EXPORT_SYMBOL_GPL(crypto_chacha20_setkey); + +int crypto_chacha20_crypt(struct skcipher_request *req) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm); + struct skcipher_walk walk; + u32 state[16]; + int err; + + err = skcipher_walk_virt(&walk, req, true); + + crypto_chacha20_init(state, ctx, walk.iv); + + while (walk.nbytes > 0) { + unsigned int nbytes = walk.nbytes; + + if (nbytes < walk.total) + nbytes = round_down(nbytes, walk.stride); + + chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, + nbytes); + err = skcipher_walk_done(&walk, walk.nbytes - nbytes); + } + + return err; +} +EXPORT_SYMBOL_GPL(crypto_chacha20_crypt); + +static struct skcipher_alg alg = { + .base.cra_name = "chacha20", + .base.cra_driver_name = "chacha20-generic", + .base.cra_priority = 100, + .base.cra_blocksize = 1, + .base.cra_ctxsize = sizeof(struct chacha20_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = CHACHA20_KEY_SIZE, + .max_keysize = CHACHA20_KEY_SIZE, + .ivsize = CHACHA20_IV_SIZE, + .chunksize = CHACHA20_BLOCK_SIZE, + .setkey = crypto_chacha20_setkey, + .encrypt = crypto_chacha20_crypt, + .decrypt = crypto_chacha20_crypt, +}; + +static int __init chacha20_generic_mod_init(void) +{ + return crypto_register_skcipher(&alg); +} + +static void __exit chacha20_generic_mod_fini(void) +{ + crypto_unregister_skcipher(&alg); +} + +module_init(chacha20_generic_mod_init); +module_exit(chacha20_generic_mod_fini); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); +MODULE_DESCRIPTION("chacha20 cipher algorithm"); +MODULE_ALIAS_CRYPTO("chacha20"); +MODULE_ALIAS_CRYPTO("chacha20-generic"); |