| 1 |
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| 2 | |
| 3 | * CTR: Counter mode
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| 4 | *
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| 5 | * Copyright (c) 2007 Herbert Xu <[email protected]>
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| 6 |
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| 7 |
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| 8 | #ifndef _CRYPTO_CTR_H
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| 9 | #define _CRYPTO_CTR_H
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| 10 |
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| 11 | #include <crypto/algapi.h>
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| 12 | #include <crypto/internal/skcipher.h>
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| 13 | #include <linux/string.h>
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| 14 | #include <linux/types.h>
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| 15 |
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| 16 | #define CTR_RFC3686_NONCE_SIZE 4
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| 17 | #define CTR_RFC3686_IV_SIZE 8
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| 18 | #define CTR_RFC3686_BLOCK_SIZE 16
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| 19 |
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| 20 | static inline int crypto_ctr_encrypt_walk(struct skcipher_request *req,
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| 21 | void (*fn)(struct crypto_skcipher *,
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| 22 | const u8 *, u8 *))
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| 23 | {
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| 24 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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| 25 | int blocksize = crypto_skcipher_chunksize(tfm);
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| 26 | u8 buf[MAX_CIPHER_BLOCKSIZE];
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| 27 | struct skcipher_walk walk;
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| 28 | int err;
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| 29 |
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| 30 |
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| 31 | if (WARN_ON_ONCE(!is_power_of_2(blocksize)))
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| 32 | return -EINVAL;
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| 33 |
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| 34 | err = skcipher_walk_virt(&walk, req, false);
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| 35 |
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| 36 | while (walk.nbytes > 0) {
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| 37 | u8 *dst = walk.dst.virt.addr;
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| 38 | u8 *src = walk.src.virt.addr;
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| 39 | int nbytes = walk.nbytes;
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| 40 | int tail = 0;
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| 41 |
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| 42 | if (nbytes < walk.total) {
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| 43 | tail = walk.nbytes & (blocksize - 1);
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| 44 | nbytes -= tail;
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| 45 | }
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| 46 |
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| 47 | do {
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| 48 | int bsize = min(nbytes, blocksize);
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| 49 |
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| 50 | fn(tfm, walk.iv, buf);
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| 51 |
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| 52 | crypto_xor_cpy(dst, src, buf, bsize);
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| 53 | crypto_inc(walk.iv, blocksize);
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| 54 |
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| 55 | dst += bsize;
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| 56 | src += bsize;
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| 57 | nbytes -= bsize;
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| 58 | } while (nbytes > 0);
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| 59 |
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| 60 | err = skcipher_walk_done(&walk, tail);
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| 61 | }
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| 62 | return err;
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| 63 | }
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| 64 |
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| 65 | #endif
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