chacha20_generic.c 5.98 KB
 Martin Willi committed Jun 04, 2015 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ``````/* * 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 #include #include #include `````` Martin Willi committed Jul 17, 2015 16 ``````#include `````` Martin Willi committed Jun 04, 2015 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 `````` static inline u32 rotl32(u32 v, u8 n) { return (v << n) | (v >> (sizeof(v) * 8 - n)); } static inline u32 le32_to_cpuvp(const void *p) { return le32_to_cpup(p); } static void chacha20_block(u32 *state, void *stream) { u32 x[16], *out = stream; int i; for (i = 0; i < ARRAY_SIZE(x); i++) x[i] = state[i]; for (i = 0; i < 20; i += 2) { x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16); x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16); x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16); x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16); x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12); x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12); x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12); x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12); x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8); x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8); x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8); x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8); x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7); x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7); x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7); x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7); x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16); x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16); x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16); x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16); x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12); x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12); x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12); x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12); x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8); x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8); x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8); x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8); x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7); x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7); x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7); x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7); } for (i = 0; i < ARRAY_SIZE(x); i++) out[i] = cpu_to_le32(x[i] + state[i]); state[12]++; } static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src, unsigned int bytes) { u8 stream[CHACHA20_BLOCK_SIZE]; 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); } } `````` Martin Willi committed Jul 17, 2015 104 ``````void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv) `````` Martin Willi committed Jun 04, 2015 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 ``````{ static const char constant[16] = "expand 32-byte k"; state[0] = le32_to_cpuvp(constant + 0); state[1] = le32_to_cpuvp(constant + 4); state[2] = le32_to_cpuvp(constant + 8); state[3] = le32_to_cpuvp(constant + 12); 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] = le32_to_cpuvp(iv + 0); state[13] = le32_to_cpuvp(iv + 4); state[14] = le32_to_cpuvp(iv + 8); state[15] = le32_to_cpuvp(iv + 12); } `````` Martin Willi committed Jul 17, 2015 125 ``````EXPORT_SYMBOL_GPL(crypto_chacha20_init); `````` Martin Willi committed Jun 04, 2015 126 `````` `````` Martin Willi committed Jul 17, 2015 127 ``````int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key, `````` Martin Willi committed Jun 04, 2015 128 129 130 131 132 133 134 135 136 137 138 139 140 `````` unsigned int keysize) { struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm); int i; if (keysize != CHACHA20_KEY_SIZE) return -EINVAL; for (i = 0; i < ARRAY_SIZE(ctx->key); i++) ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32)); return 0; } `````` Martin Willi committed Jul 17, 2015 141 ``````EXPORT_SYMBOL_GPL(crypto_chacha20_setkey); `````` Martin Willi committed Jun 04, 2015 142 `````` `````` Martin Willi committed Jul 17, 2015 143 ``````int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst, `````` Martin Willi committed Jun 04, 2015 144 145 146 147 148 149 150 151 152 `````` struct scatterlist *src, unsigned int nbytes) { struct blkcipher_walk walk; u32 state[16]; int err; blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE); `````` Martin Willi committed Jul 17, 2015 153 `````` crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv); `````` Martin Willi committed Jun 04, 2015 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 `````` while (walk.nbytes >= CHACHA20_BLOCK_SIZE) { chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE)); err = blkcipher_walk_done(desc, &walk, walk.nbytes % CHACHA20_BLOCK_SIZE); } if (walk.nbytes) { chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, walk.nbytes); err = blkcipher_walk_done(desc, &walk, 0); } return err; } `````` Martin Willi committed Jul 17, 2015 170 ``````EXPORT_SYMBOL_GPL(crypto_chacha20_crypt); `````` Martin Willi committed Jun 04, 2015 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 `````` static struct crypto_alg alg = { .cra_name = "chacha20", .cra_driver_name = "chacha20-generic", .cra_priority = 100, .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, .cra_blocksize = 1, .cra_type = &crypto_blkcipher_type, .cra_ctxsize = sizeof(struct chacha20_ctx), .cra_alignmask = sizeof(u32) - 1, .cra_module = THIS_MODULE, .cra_u = { .blkcipher = { .min_keysize = CHACHA20_KEY_SIZE, .max_keysize = CHACHA20_KEY_SIZE, `````` Martin Willi committed Jul 17, 2015 186 `````` .ivsize = CHACHA20_IV_SIZE, `````` Martin Willi committed Jun 04, 2015 187 `````` .geniv = "seqiv", `````` Martin Willi committed Jul 17, 2015 188 189 190 `````` .setkey = crypto_chacha20_setkey, .encrypt = crypto_chacha20_crypt, .decrypt = crypto_chacha20_crypt, `````` Martin Willi committed Jun 04, 2015 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 `````` }, }, }; static int __init chacha20_generic_mod_init(void) { return crypto_register_alg(&alg); } static void __exit chacha20_generic_mod_fini(void) { crypto_unregister_alg(&alg); } module_init(chacha20_generic_mod_init); module_exit(chacha20_generic_mod_fini); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Martin Willi "); MODULE_DESCRIPTION("chacha20 cipher algorithm"); MODULE_ALIAS_CRYPTO("chacha20"); MODULE_ALIAS_CRYPTO("chacha20-generic");``````