lib/crypto/poly1305.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Poly1305 authenticator algorithm, RFC7539
   4  *
   5  * Copyright (C) 2015 Martin Willi
   6  *
   7  * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
   8  */
   9
  10 #include <crypto/internal/poly1305.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <asm/unaligned.h>
  14
  15 void poly1305_init_generic(struct poly1305_desc_ctx *desc, const u8 *key)
  16 {
  17         poly1305_core_setkey(&desc->core_r, key);
  18         desc->s[0] = get_unaligned_le32(key + 16);
  19         desc->s[1] = get_unaligned_le32(key + 20);
  20         desc->s[2] = get_unaligned_le32(key + 24);
  21         desc->s[3] = get_unaligned_le32(key + 28);
  22         poly1305_core_init(&desc->h);
  23         desc->buflen = 0;
  24         desc->sset = true;
  25         desc->rset = 2;
  26 }
  27 EXPORT_SYMBOL_GPL(poly1305_init_generic);
  28
  29 void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
  30                              unsigned int nbytes)
  31 {
  32         unsigned int bytes;
  33
  34         if (unlikely(desc->buflen)) {
  35                 bytes = min(nbytes, POLY1305_BLOCK_SIZE - desc->buflen);
  36                 memcpy(desc->buf + desc->buflen, src, bytes);
  37                 src += bytes;
  38                 nbytes -= bytes;
  39                 desc->buflen += bytes;
  40
  41                 if (desc->buflen == POLY1305_BLOCK_SIZE) {
  42                         poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf,
  43                                              1, 1);
  44                         desc->buflen = 0;
  45                 }
  46         }
  47
  48         if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
  49                 poly1305_core_blocks(&desc->h, &desc->core_r, src,
  50                                      nbytes / POLY1305_BLOCK_SIZE, 1);
  51                 src += nbytes - (nbytes % POLY1305_BLOCK_SIZE);
  52                 nbytes %= POLY1305_BLOCK_SIZE;
  53         }
  54
  55         if (unlikely(nbytes)) {
  56                 desc->buflen = nbytes;
  57                 memcpy(desc->buf, src, nbytes);
  58         }
  59 }
  60 EXPORT_SYMBOL_GPL(poly1305_update_generic);
  61
  62 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *dst)
  63 {
  64         if (unlikely(desc->buflen)) {
  65                 desc->buf[desc->buflen++] = 1;
  66                 memset(desc->buf + desc->buflen, 0,
  67                        POLY1305_BLOCK_SIZE - desc->buflen);
  68                 poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf, 1, 0);
  69         }
  70
  71         poly1305_core_emit(&desc->h, desc->s, dst);
  72         *desc = (struct poly1305_desc_ctx){};
  73 }
  74 EXPORT_SYMBOL_GPL(poly1305_final_generic);
  75
  76 MODULE_LICENSE("GPL");
  77 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");