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/export.h>
 12#include <linux/kernel.h>
 13#include <linux/module.h>
 14#include <linux/string.h>
 15#include <linux/unaligned.h>
 16
 17#ifdef CONFIG_CRYPTO_LIB_POLY1305_ARCH
 18#include "poly1305.h" /* $(SRCARCH)/poly1305.h */
 19#else
 20#define poly1305_block_init	poly1305_block_init_generic
 21#define poly1305_blocks		poly1305_blocks_generic
 22#define poly1305_emit		poly1305_emit_generic
 23#endif
 24
 25void poly1305_init(struct poly1305_desc_ctx *desc,
 26		   const u8 key[POLY1305_KEY_SIZE])
 27{
 28	desc->s[0] = get_unaligned_le32(key + 16);
 29	desc->s[1] = get_unaligned_le32(key + 20);
 30	desc->s[2] = get_unaligned_le32(key + 24);
 31	desc->s[3] = get_unaligned_le32(key + 28);
 32	desc->buflen = 0;
 33	poly1305_block_init(&desc->state, key);
 34}
 35EXPORT_SYMBOL(poly1305_init);
 36
 37void poly1305_update(struct poly1305_desc_ctx *desc,
 38		     const u8 *src, unsigned int nbytes)
 39{
 40	if (desc->buflen + nbytes >= POLY1305_BLOCK_SIZE) {
 41		unsigned int bulk_len;
 42
 43		if (desc->buflen) {
 44			unsigned int l = POLY1305_BLOCK_SIZE - desc->buflen;
 45
 46			memcpy(&desc->buf[desc->buflen], src, l);
 47			src += l;
 48			nbytes -= l;
 49
 50			poly1305_blocks(&desc->state, desc->buf,
 51					POLY1305_BLOCK_SIZE, 1);
 52			desc->buflen = 0;
 53		}
 54
 55		bulk_len = round_down(nbytes, POLY1305_BLOCK_SIZE);
 56		nbytes %= POLY1305_BLOCK_SIZE;
 57
 58		if (bulk_len) {
 59			poly1305_blocks(&desc->state, src, bulk_len, 1);
 60			src += bulk_len;
 61		}
 62	}
 63	if (nbytes) {
 64		memcpy(&desc->buf[desc->buflen], src, nbytes);
 65		desc->buflen += nbytes;
 66	}
 67}
 68EXPORT_SYMBOL(poly1305_update);
 69
 70void poly1305_final(struct poly1305_desc_ctx *desc, u8 *dst)
 71{
 72	if (unlikely(desc->buflen)) {
 73		desc->buf[desc->buflen++] = 1;
 74		memset(desc->buf + desc->buflen, 0,
 75		       POLY1305_BLOCK_SIZE - desc->buflen);
 76		poly1305_blocks(&desc->state, desc->buf, POLY1305_BLOCK_SIZE,
 77				0);
 78	}
 79
 80	poly1305_emit(&desc->state.h, dst, desc->s);
 81	*desc = (struct poly1305_desc_ctx){};
 82}
 83EXPORT_SYMBOL(poly1305_final);
 84
 85#ifdef poly1305_mod_init_arch
 86static int __init poly1305_mod_init(void)
 87{
 88	poly1305_mod_init_arch();
 89	return 0;
 90}
 91subsys_initcall(poly1305_mod_init);
 92
 93static void __exit poly1305_mod_exit(void)
 94{
 95}
 96module_exit(poly1305_mod_exit);
 97#endif
 98
 99MODULE_LICENSE("GPL");
100MODULE_DESCRIPTION("Poly1305 authenticator algorithm, RFC7539");