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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 | /* * 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) { u32 stream[CHACHA20_BLOCK_WORDS]; if (dst != src) memcpy(dst, src, bytes); while (bytes >= CHACHA20_BLOCK_SIZE) { chacha20_block(state, stream); crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE); bytes -= CHACHA20_BLOCK_SIZE; dst += CHACHA20_BLOCK_SIZE; } if (bytes) { chacha20_block(state, stream); crypto_xor(dst, (const u8 *)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"); |