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,
  16                            const u8 key[POLY1305_KEY_SIZE])
  17 {
  18         poly1305_core_setkey(&desc->core_r, key);
  19         desc->s[0] = get_unaligned_le32(key + 16);
  20         desc->s[1] = get_unaligned_le32(key + 20);
  21         desc->s[2] = get_unaligned_le32(key + 24);
  22         desc->s[3] = get_unaligned_le32(key + 28);
  23         poly1305_core_init(&desc->h);
  24         desc->buflen = 0;
  25         desc->sset = true;
  26         desc->rset = 2;
  27 }
  28 EXPORT_SYMBOL_GPL(poly1305_init_generic);
  29
  30 void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
  31                              unsigned int nbytes)
  32 {
  33         unsigned int bytes;
  34
  35         if (unlikely(desc->buflen)) {
  36                 bytes = min(nbytes, POLY1305_BLOCK_SIZE - desc->buflen);
  37                 memcpy(desc->buf + desc->buflen, src, bytes);
  38                 src += bytes;
  39                 nbytes -= bytes;
  40                 desc->buflen += bytes;
  41
  42                 if (desc->buflen == POLY1305_BLOCK_SIZE) {
  43                         poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf,
  44                                              1, 1);
  45                         desc->buflen = 0;
  46                 }
  47         }
  48
  49         if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
  50                 poly1305_core_blocks(&desc->h, &desc->core_r, src,
  51                                      nbytes / POLY1305_BLOCK_SIZE, 1);
  52                 src += nbytes - (nbytes % POLY1305_BLOCK_SIZE);
  53                 nbytes %= POLY1305_BLOCK_SIZE;
  54         }
  55
  56         if (unlikely(nbytes)) {
  57                 desc->buflen = nbytes;
  58                 memcpy(desc->buf, src, nbytes);
  59         }
  60 }
  61 EXPORT_SYMBOL_GPL(poly1305_update_generic);
  62
  63 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *dst)
  64 {
  65         if (unlikely(desc->buflen)) {
  66                 desc->buf[desc->buflen++] = 1;
  67                 memset(desc->buf + desc->buflen, 0,
  68                        POLY1305_BLOCK_SIZE - desc->buflen);
  69                 poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf, 1, 0);
  70         }
  71
  72         poly1305_core_emit(&desc->h, desc->s, dst);
  73         *desc = (struct poly1305_desc_ctx){};
  74 }
  75 EXPORT_SYMBOL_GPL(poly1305_final_generic);
  76
  77 MODULE_LICENSE("GPL");
  78 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");