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Diffstat (limited to 'crypto/poly1305_generic.c')
| -rw-r--r-- | crypto/poly1305_generic.c | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c new file mode 100644 index 000000000000..387b5c887a80 --- /dev/null +++ b/crypto/poly1305_generic.c @@ -0,0 +1,321 @@ +/* + * Poly1305 authenticator algorithm, RFC7539 + * + * Copyright (C) 2015 Martin Willi + * + * Based on public domain code by Andrew Moon and Daniel J. Bernstein. + * + * 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/algapi.h> +#include <crypto/internal/hash.h> +#include <linux/crypto.h> +#include <linux/kernel.h> +#include <linux/module.h> + +#define POLY1305_BLOCK_SIZE 16 +#define POLY1305_KEY_SIZE 32 +#define POLY1305_DIGEST_SIZE 16 + +struct poly1305_desc_ctx { + /* key */ + u32 r[5]; + /* finalize key */ + u32 s[4]; + /* accumulator */ + u32 h[5]; + /* partial buffer */ + u8 buf[POLY1305_BLOCK_SIZE]; + /* bytes used in partial buffer */ + unsigned int buflen; + /* r key has been set */ + bool rset; + /* s key has been set */ + bool sset; +}; + +static inline u64 mlt(u64 a, u64 b) +{ + return a * b; +} + +static inline u32 sr(u64 v, u_char n) +{ + return v >> n; +} + +static inline u32 and(u32 v, u32 mask) +{ + return v & mask; +} + +static inline u32 le32_to_cpuvp(const void *p) +{ + return le32_to_cpup(p); +} + +static int poly1305_init(struct shash_desc *desc) +{ + struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); + + memset(dctx->h, 0, sizeof(dctx->h)); + dctx->buflen = 0; + dctx->rset = false; + dctx->sset = false; + + return 0; +} + +static int poly1305_setkey(struct crypto_shash *tfm, + const u8 *key, unsigned int keylen) +{ + /* Poly1305 requires a unique key for each tag, which implies that + * we can't set it on the tfm that gets accessed by multiple users + * simultaneously. Instead we expect the key as the first 32 bytes in + * the update() call. */ + return -ENOTSUPP; +} + +static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key) +{ + /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ + dctx->r[0] = (le32_to_cpuvp(key + 0) >> 0) & 0x3ffffff; + dctx->r[1] = (le32_to_cpuvp(key + 3) >> 2) & 0x3ffff03; + dctx->r[2] = (le32_to_cpuvp(key + 6) >> 4) & 0x3ffc0ff; + dctx->r[3] = (le32_to_cpuvp(key + 9) >> 6) & 0x3f03fff; + dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff; +} + +static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key) +{ + dctx->s[0] = le32_to_cpuvp(key + 0); + dctx->s[1] = le32_to_cpuvp(key + 4); + dctx->s[2] = le32_to_cpuvp(key + 8); + dctx->s[3] = le32_to_cpuvp(key + 12); +} + +static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx, + const u8 *src, unsigned int srclen, + u32 hibit) +{ + u32 r0, r1, r2, r3, r4; + u32 s1, s2, s3, s4; + u32 h0, h1, h2, h3, h4; + u64 d0, d1, d2, d3, d4; + + if (unlikely(!dctx->sset)) { + if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { + poly1305_setrkey(dctx, src); + src += POLY1305_BLOCK_SIZE; + srclen -= POLY1305_BLOCK_SIZE; + dctx->rset = true; + } + if (srclen >= POLY1305_BLOCK_SIZE) { + poly1305_setskey(dctx, src); + src += POLY1305_BLOCK_SIZE; + srclen -= POLY1305_BLOCK_SIZE; + dctx->sset = true; + } + } + + r0 = dctx->r[0]; + r1 = dctx->r[1]; + r2 = dctx->r[2]; + r3 = dctx->r[3]; + r4 = dctx->r[4]; + + s1 = r1 * 5; + s2 = r2 * 5; + s3 = r3 * 5; + s4 = r4 * 5; + + h0 = dctx->h[0]; + h1 = dctx->h[1]; + h2 = dctx->h[2]; + h3 = dctx->h[3]; + h4 = dctx->h[4]; + + while (likely(srclen >= POLY1305_BLOCK_SIZE)) { + + /* h += m[i] */ + h0 += (le32_to_cpuvp(src + 0) >> 0) & 0x3ffffff; + h1 += (le32_to_cpuvp(src + 3) >> 2) & 0x3ffffff; + h2 += (le32_to_cpuvp(src + 6) >> 4) & 0x3ffffff; + h3 += (le32_to_cpuvp(src + 9) >> 6) & 0x3ffffff; + h4 += (le32_to_cpuvp(src + 12) >> 8) | hibit; + + /* h *= r */ + d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) + + mlt(h3, s2) + mlt(h4, s1); + d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) + + mlt(h3, s3) + mlt(h4, s2); + d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) + + mlt(h3, s4) + mlt(h4, s3); + d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) + + mlt(h3, r0) + mlt(h4, s4); + d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) + + mlt(h3, r1) + mlt(h4, r0); + + /* (partial) h %= p */ + d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff); + d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff); + d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff); + d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff); + h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff); + h1 += h0 >> 26; h0 = h0 & 0x3ffffff; + + src += POLY1305_BLOCK_SIZE; + srclen -= POLY1305_BLOCK_SIZE; + } + + dctx->h[0] = h0; + dctx->h[1] = h1; + dctx->h[2] = h2; + dctx->h[3] = h3; + dctx->h[4] = h4; + + return srclen; +} + +static int poly1305_update(struct shash_desc *desc, + const u8 *src, unsigned int srclen) +{ + struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); + unsigned int bytes; + + if (unlikely(dctx->buflen)) { + bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen); + memcpy(dctx->buf + dctx->buflen, src, bytes); + src += bytes; + srclen -= bytes; + dctx->buflen += bytes; + + if (dctx->buflen == POLY1305_BLOCK_SIZE) { + poly1305_blocks(dctx, dctx->buf, + POLY1305_BLOCK_SIZE, 1 << 24); + dctx->buflen = 0; + } + } + + if (likely(srclen >= POLY1305_BLOCK_SIZE)) { + bytes = poly1305_blocks(dctx, src, srclen, 1 << 24); + src += srclen - bytes; + srclen = bytes; + } + + if (unlikely(srclen)) { + dctx->buflen = srclen; + memcpy(dctx->buf, src, srclen); + } + + return 0; +} + +static int poly1305_final(struct shash_desc *desc, u8 *dst) +{ + struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); + __le32 *mac = (__le32 *)dst; + u32 h0, h1, h2, h3, h4; + u32 g0, g1, g2, g3, g4; + u32 mask; + u64 f = 0; + + if (unlikely(!dctx->sset)) + return -ENOKEY; + + if (unlikely(dctx->buflen)) { + dctx->buf[dctx->buflen++] = 1; + memset(dctx->buf + dctx->buflen, 0, + POLY1305_BLOCK_SIZE - dctx->buflen); + poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); + } + + /* fully carry h */ + h0 = dctx->h[0]; + h1 = dctx->h[1]; + h2 = dctx->h[2]; + h3 = dctx->h[3]; + h4 = dctx->h[4]; + + h2 += (h1 >> 26); h1 = h1 & 0x3ffffff; + h3 += (h2 >> 26); h2 = h2 & 0x3ffffff; + h4 += (h3 >> 26); h3 = h3 & 0x3ffffff; + h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff; + h1 += (h0 >> 26); h0 = h0 & 0x3ffffff; + + /* compute h + -p */ + g0 = h0 + 5; + g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff; + g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff; + g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff; + g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff; + + /* select h if h < p, or h + -p if h >= p */ + mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1; + g0 &= mask; + g1 &= mask; + g2 &= mask; + g3 &= mask; + g4 &= mask; + mask = ~mask; + h0 = (h0 & mask) | g0; + h1 = (h1 & mask) | g1; + h2 = (h2 & mask) | g2; + h3 = (h3 & mask) | g3; + h4 = (h4 & mask) | g4; + + /* h = h % (2^128) */ + h0 = (h0 >> 0) | (h1 << 26); + h1 = (h1 >> 6) | (h2 << 20); + h2 = (h2 >> 12) | (h3 << 14); + h3 = (h3 >> 18) | (h4 << 8); + + /* mac = (h + s) % (2^128) */ + f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f); + f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f); + f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f); + f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f); + + return 0; +} + +static struct shash_alg poly1305_alg = { + .digestsize = POLY1305_DIGEST_SIZE, + .init = poly1305_init, + .update = poly1305_update, + .final = poly1305_final, + .setkey = poly1305_setkey, + .descsize = sizeof(struct poly1305_desc_ctx), + .base = { + .cra_name = "poly1305", + .cra_driver_name = "poly1305-generic", + .cra_priority = 100, + .cra_flags = CRYPTO_ALG_TYPE_SHASH, + .cra_alignmask = sizeof(u32) - 1, + .cra_blocksize = POLY1305_BLOCK_SIZE, + .cra_module = THIS_MODULE, + }, +}; + +static int __init poly1305_mod_init(void) +{ + return crypto_register_shash(&poly1305_alg); +} + +static void __exit poly1305_mod_exit(void) +{ + crypto_unregister_shash(&poly1305_alg); +} + +module_init(poly1305_mod_init); +module_exit(poly1305_mod_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); +MODULE_DESCRIPTION("Poly1305 authenticator"); +MODULE_ALIAS_CRYPTO("poly1305"); +MODULE_ALIAS_CRYPTO("poly1305-generic"); |