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92 lines
2.5 KiB
C
92 lines
2.5 KiB
C
/* umac-set-key.c
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Copyright (C) 2013 Niels Möller
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This file is part of GNU Nettle.
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GNU Nettle is free software: you can redistribute it and/or
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modify it under the terms of either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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or both in parallel, as here.
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GNU Nettle is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see http://www.gnu.org/licenses/.
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*/
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#if HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <string.h>
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#include "umac.h"
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#include "umac-internal.h"
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#include "macros.h"
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#include "bswap-internal.h"
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static void
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umac_kdf (struct aes128_ctx *aes, unsigned index, unsigned length, uint8_t *dst)
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{
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uint8_t block[AES_BLOCK_SIZE];
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uint64_t count;
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WRITE_UINT64 (block, (uint64_t) index);
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for (count = 1; length >= AES_BLOCK_SIZE;
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length -= AES_BLOCK_SIZE, dst += AES_BLOCK_SIZE, count++)
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{
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WRITE_UINT64 (block + 8, count);
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aes128_encrypt (aes, AES_BLOCK_SIZE, dst, block);
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}
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if (length > 0)
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{
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WRITE_UINT64 (block + 8, count);
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aes128_encrypt (aes, AES_BLOCK_SIZE, block, block);
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memcpy (dst, block, length);
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}
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}
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void
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_nettle_umac_set_key (uint32_t *l1_key, uint32_t *l2_key,
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uint64_t *l3_key1, uint32_t *l3_key2,
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struct aes128_ctx *aes, const uint8_t *key, unsigned n)
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{
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unsigned size;
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uint8_t buffer[UMAC_KEY_SIZE];
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aes128_set_encrypt_key (aes, key);
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size = UMAC_BLOCK_SIZE / 4 + 4*(n-1);
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umac_kdf (aes, 1, size * sizeof(uint32_t), (uint8_t *) l1_key);
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bswap32_n_if_le (size, l1_key);
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size = 6*n;
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umac_kdf (aes, 2, size * sizeof(uint32_t), (uint8_t *) l2_key);
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_nettle_umac_l2_init (size, l2_key);
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size = 8*n;
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umac_kdf (aes, 3, size * sizeof(uint64_t), (uint8_t *) l3_key1);
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_nettle_umac_l3_init (size, l3_key1);
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/* No need to byteswap these subkeys. */
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umac_kdf (aes, 4, n * sizeof(uint32_t), (uint8_t *) l3_key2);
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umac_kdf (aes, 0, UMAC_KEY_SIZE, buffer);
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aes128_set_encrypt_key (aes, buffer);
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}
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