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crypto/poly1305_generic.c
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/* * 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> |
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#include <crypto/poly1305.h> |
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#include <linux/crypto.h> #include <linux/kernel.h> #include <linux/module.h> |
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#include <asm/unaligned.h> |
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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; } |
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int crypto_poly1305_init(struct shash_desc *desc) |
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{ struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); memset(dctx->h, 0, sizeof(dctx->h)); dctx->buflen = 0; |
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dctx->rset = false; dctx->sset = false; |
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return 0; } |
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EXPORT_SYMBOL_GPL(crypto_poly1305_init); |
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static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key) { |
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/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ |
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dctx->r[0] = (get_unaligned_le32(key + 0) >> 0) & 0x3ffffff; dctx->r[1] = (get_unaligned_le32(key + 3) >> 2) & 0x3ffff03; dctx->r[2] = (get_unaligned_le32(key + 6) >> 4) & 0x3ffc0ff; dctx->r[3] = (get_unaligned_le32(key + 9) >> 6) & 0x3f03fff; dctx->r[4] = (get_unaligned_le32(key + 12) >> 8) & 0x00fffff; |
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} |
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static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key) { |
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dctx->s[0] = get_unaligned_le32(key + 0); dctx->s[1] = get_unaligned_le32(key + 4); dctx->s[2] = get_unaligned_le32(key + 8); dctx->s[3] = get_unaligned_le32(key + 12); |
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} |
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/* * 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. */ |
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unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx, const u8 *src, unsigned int srclen) |
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{ |
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if (!dctx->sset) { |
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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; } } |
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return srclen; } EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey); 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; unsigned int datalen; if (unlikely(!dctx->sset)) { datalen = crypto_poly1305_setdesckey(dctx, src, srclen); src += srclen - datalen; srclen = datalen; } |
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r0 = dctx->r[0]; r1 = dctx->r[1]; r2 = dctx->r[2]; r3 = dctx->r[3]; r4 = dctx->r[4]; |
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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] */ |
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h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff; h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff; h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff; h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff; h4 += (get_unaligned_le32(src + 12) >> 8) | hibit; |
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/* 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; } |
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int crypto_poly1305_update(struct shash_desc *desc, |
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const u8 *src, unsigned int srclen) { struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); |
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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) { |
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poly1305_blocks(dctx, dctx->buf, |
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POLY1305_BLOCK_SIZE, 1 << 24); dctx->buflen = 0; } } if (likely(srclen >= POLY1305_BLOCK_SIZE)) { |
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bytes = poly1305_blocks(dctx, src, srclen, 1 << 24); |
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src += srclen - bytes; srclen = bytes; } if (unlikely(srclen)) { dctx->buflen = srclen; memcpy(dctx->buf, src, srclen); } return 0; } |
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EXPORT_SYMBOL_GPL(crypto_poly1305_update); |
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int crypto_poly1305_final(struct shash_desc *desc, u8 *dst) |
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{ struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); |
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__le32 *mac = (__le32 *)dst; u32 h0, h1, h2, h3, h4; u32 g0, g1, g2, g3, g4; u32 mask; u64 f = 0; |
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if (unlikely(!dctx->sset)) return -ENOKEY; |
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if (unlikely(dctx->buflen)) { dctx->buf[dctx->buflen++] = 1; memset(dctx->buf + dctx->buflen, 0, POLY1305_BLOCK_SIZE - dctx->buflen); |
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poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); |
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} /* 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) */ |
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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); |
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return 0; } |
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EXPORT_SYMBOL_GPL(crypto_poly1305_final); |
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static struct shash_alg poly1305_alg = { .digestsize = POLY1305_DIGEST_SIZE, |
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.init = crypto_poly1305_init, .update = crypto_poly1305_update, .final = crypto_poly1305_final, |
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.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, |
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.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"); |