lib/crypto/poly1305.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Poly1305 authenticator algorithm, RFC7539
0004  *
0005  * Copyright (C) 2015 Martin Willi
0006  *
0007  * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
0008  */
0009
0010 #include <crypto/internal/poly1305.h>
0011 #include <linux/kernel.h>
0012 #include <linux/module.h>
0013 #include <asm/unaligned.h>
0014
0015 void poly1305_init_generic(struct poly1305_desc_ctx *desc,
0016                const u8 key[POLY1305_KEY_SIZE])
0017 {
0018     poly1305_core_setkey(&desc->core_r, key);
0019     desc->s[0] = get_unaligned_le32(key + 16);
0020     desc->s[1] = get_unaligned_le32(key + 20);
0021     desc->s[2] = get_unaligned_le32(key + 24);
0022     desc->s[3] = get_unaligned_le32(key + 28);
0023     poly1305_core_init(&desc->h);
0024     desc->buflen = 0;
0025     desc->sset = true;
0026     desc->rset = 2;
0027 }
0028 EXPORT_SYMBOL_GPL(poly1305_init_generic);
0029
0030 void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
0031                  unsigned int nbytes)
0032 {
0033     unsigned int bytes;
0034
0035     if (unlikely(desc->buflen)) {
0036         bytes = min(nbytes, POLY1305_BLOCK_SIZE - desc->buflen);
0037         memcpy(desc->buf + desc->buflen, src, bytes);
0038         src += bytes;
0039         nbytes -= bytes;
0040         desc->buflen += bytes;
0041
0042         if (desc->buflen == POLY1305_BLOCK_SIZE) {
0043             poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf,
0044                          1, 1);
0045             desc->buflen = 0;
0046         }
0047     }
0048
0049     if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
0050         poly1305_core_blocks(&desc->h, &desc->core_r, src,
0051                      nbytes / POLY1305_BLOCK_SIZE, 1);
0052         src += nbytes - (nbytes % POLY1305_BLOCK_SIZE);
0053         nbytes %= POLY1305_BLOCK_SIZE;
0054     }
0055
0056     if (unlikely(nbytes)) {
0057         desc->buflen = nbytes;
0058         memcpy(desc->buf, src, nbytes);
0059     }
0060 }
0061 EXPORT_SYMBOL_GPL(poly1305_update_generic);
0062
0063 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *dst)
0064 {
0065     if (unlikely(desc->buflen)) {
0066         desc->buf[desc->buflen++] = 1;
0067         memset(desc->buf + desc->buflen, 0,
0068                POLY1305_BLOCK_SIZE - desc->buflen);
0069         poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf, 1, 0);
0070     }
0071
0072     poly1305_core_emit(&desc->h, desc->s, dst);
0073     *desc = (struct poly1305_desc_ctx){};
0074 }
0075 EXPORT_SYMBOL_GPL(poly1305_final_generic);
0076
0077 MODULE_LICENSE("GPL");
0078 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");