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65 lines
1.4 KiB
65 lines
1.4 KiB
/* 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 <[email protected]> |
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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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