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Unlike chaining modes such as CBC, stream ciphers other than CTR usually hold an internal state that must be preserved if the operation is to be done piecemeal. This has not been represented in the API, resulting in the inability to split up stream cipher operations. This patch adds the basic representation of an internal state to skcipher and lskcipher. In the interest of backwards compatibility, the default has been set such that existing users are assumed to be operating in one go as opposed to piecemeal. With the new API, each lskcipher/skcipher algorithm has a new attribute called statesize. For skcipher, this is the size of the buffer that can be exported or imported similar to ahash. For lskcipher, instead of providing a buffer of ivsize, the user now has to provide a buffer of ivsize + statesize. Each skcipher operation is assumed to be final as they are now, but this may be overridden with a request flag. When the override occurs, the user may then export the partial state and reimport it later. For lskcipher operations this is reversed. All operations are not final and the state will be exported unless the FINAL bit is set. However, the CONT bit still has to be set for the state to be used. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Cryptographic API
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*
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* ARC4 Cipher Algorithm
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*
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* Jon Oberheide <jon@oberheide.org>
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*/
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#include <crypto/arc4.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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static int crypto_arc4_setkey(struct crypto_lskcipher *tfm, const u8 *in_key,
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unsigned int key_len)
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{
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struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);
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return arc4_setkey(ctx, in_key, key_len);
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}
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static int crypto_arc4_crypt(struct crypto_lskcipher *tfm, const u8 *src,
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u8 *dst, unsigned nbytes, u8 *iv, u32 flags)
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{
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struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);
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arc4_crypt(ctx, dst, src, nbytes);
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return 0;
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}
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static int crypto_arc4_init(struct crypto_lskcipher *tfm)
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{
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pr_warn_ratelimited("\"%s\" (%ld) uses obsolete ecb(arc4) skcipher\n",
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current->comm, (unsigned long)current->pid);
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return 0;
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}
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static struct lskcipher_alg arc4_alg = {
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.co.base.cra_name = "arc4",
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.co.base.cra_driver_name = "arc4-generic",
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.co.base.cra_priority = 100,
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.co.base.cra_blocksize = ARC4_BLOCK_SIZE,
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.co.base.cra_ctxsize = sizeof(struct arc4_ctx),
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.co.base.cra_module = THIS_MODULE,
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.co.min_keysize = ARC4_MIN_KEY_SIZE,
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.co.max_keysize = ARC4_MAX_KEY_SIZE,
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.setkey = crypto_arc4_setkey,
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.encrypt = crypto_arc4_crypt,
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.decrypt = crypto_arc4_crypt,
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.init = crypto_arc4_init,
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};
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static int __init arc4_init(void)
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{
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return crypto_register_lskcipher(&arc4_alg);
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}
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static void __exit arc4_exit(void)
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{
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crypto_unregister_lskcipher(&arc4_alg);
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}
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subsys_initcall(arc4_init);
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module_exit(arc4_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
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MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
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MODULE_ALIAS_CRYPTO("ecb(arc4)");
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