66 lines
1.4 KiB
C
66 lines
1.4 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* CTR: Counter mode
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*
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* Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#ifndef _CRYPTO_CTR_H
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#define _CRYPTO_CTR_H
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#include <crypto/algapi.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#define CTR_RFC3686_NONCE_SIZE 4
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#define CTR_RFC3686_IV_SIZE 8
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#define CTR_RFC3686_BLOCK_SIZE 16
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static inline int crypto_ctr_encrypt_walk(struct skcipher_request *req,
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void (*fn)(struct crypto_skcipher *,
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const u8 *, u8 *))
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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int blocksize = crypto_skcipher_chunksize(tfm);
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u8 buf[MAX_CIPHER_BLOCKSIZE];
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struct skcipher_walk walk;
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int err;
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/* avoid integer division due to variable blocksize parameter */
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if (WARN_ON_ONCE(!is_power_of_2(blocksize)))
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return -EINVAL;
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err = skcipher_walk_virt(&walk, req, false);
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while (walk.nbytes > 0) {
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u8 *dst = walk.dst.virt.addr;
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u8 *src = walk.src.virt.addr;
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int nbytes = walk.nbytes;
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int tail = 0;
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if (nbytes < walk.total) {
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tail = walk.nbytes & (blocksize - 1);
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nbytes -= tail;
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}
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do {
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int bsize = min(nbytes, blocksize);
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fn(tfm, walk.iv, buf);
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crypto_xor_cpy(dst, src, buf, bsize);
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crypto_inc(walk.iv, blocksize);
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dst += bsize;
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src += bsize;
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nbytes -= bsize;
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} while (nbytes > 0);
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err = skcipher_walk_done(&walk, tail);
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}
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return err;
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}
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#endif /* _CRYPTO_CTR_H */
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