lib/crypto/poly1305.c

root/lib/crypto/poly1305.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Poly1305 authenticator algorithm, RFC7539
 *
 * Copyright (C) 2015 Martin Willi
 *
 * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
 */

#include <crypto/internal/poly1305.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/unaligned.h>

#ifdef CONFIG_CRYPTO_LIB_POLY1305_ARCH
#include "poly1305.h" /* $(SRCARCH)/poly1305.h */
#else
#define poly1305_block_init     poly1305_block_init_generic
#define poly1305_blocks         poly1305_blocks_generic
#define poly1305_emit           poly1305_emit_generic
#endif

void poly1305_init(struct poly1305_desc_ctx *desc,
                   const u8 key[POLY1305_KEY_SIZE])
{
        desc->s[0] = get_unaligned_le32(key + 16);
        desc->s[1] = get_unaligned_le32(key + 20);
        desc->s[2] = get_unaligned_le32(key + 24);
        desc->s[3] = get_unaligned_le32(key + 28);
        desc->buflen = 0;
        poly1305_block_init(&desc->state, key);
}
EXPORT_SYMBOL(poly1305_init);

void poly1305_update(struct poly1305_desc_ctx *desc,
                     const u8 *src, unsigned int nbytes)
{
        if (desc->buflen + nbytes >= POLY1305_BLOCK_SIZE) {
                unsigned int bulk_len;

                if (desc->buflen) {
                        unsigned int l = POLY1305_BLOCK_SIZE - desc->buflen;

                        memcpy(&desc->buf[desc->buflen], src, l);
                        src += l;
                        nbytes -= l;

                        poly1305_blocks(&desc->state, desc->buf,
                                        POLY1305_BLOCK_SIZE, 1);
                        desc->buflen = 0;
                }

                bulk_len = round_down(nbytes, POLY1305_BLOCK_SIZE);
                nbytes %= POLY1305_BLOCK_SIZE;

                if (bulk_len) {
                        poly1305_blocks(&desc->state, src, bulk_len, 1);
                        src += bulk_len;
                }
        }
        if (nbytes) {
                memcpy(&desc->buf[desc->buflen], src, nbytes);
                desc->buflen += nbytes;
        }
}
EXPORT_SYMBOL(poly1305_update);

void poly1305_final(struct poly1305_desc_ctx *desc, u8 *dst)
{
        if (unlikely(desc->buflen)) {
                desc->buf[desc->buflen++] = 1;
                memset(desc->buf + desc->buflen, 0,
                       POLY1305_BLOCK_SIZE - desc->buflen);
                poly1305_blocks(&desc->state, desc->buf, POLY1305_BLOCK_SIZE,
                                0);
        }

        poly1305_emit(&desc->state.h, dst, desc->s);
        *desc = (struct poly1305_desc_ctx){};
}
EXPORT_SYMBOL(poly1305_final);

#ifdef poly1305_mod_init_arch
static int __init poly1305_mod_init(void)
{
        poly1305_mod_init_arch();
        return 0;
}
subsys_initcall(poly1305_mod_init);

static void __exit poly1305_mod_exit(void)
{
}
module_exit(poly1305_mod_exit);
#endif

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Poly1305 authenticator algorithm, RFC7539");
Linux
