crypto: arc4 - refactor arc4 core code into separate library
Refactor the core rc4 handling so we can move most users to a library interface, permitting us to drop the cipher interface entirely in a future patch. This is part of an effort to simplify the crypto API and improve its robustness against incorrect use. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@ -4229,6 +4229,7 @@ F: crypto/
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F: drivers/crypto/
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F: include/crypto/
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F: include/linux/crypto*
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F: lib/crypto/
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CRYPTOGRAPHIC RANDOM NUMBER GENERATOR
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M: Neil Horman <nhorman@tuxdriver.com>
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@ -1237,9 +1237,13 @@ config CRYPTO_ANUBIS
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<https://www.cosic.esat.kuleuven.be/nessie/reports/>
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<http://www.larc.usp.br/~pbarreto/AnubisPage.html>
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config CRYPTO_LIB_ARC4
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tristate
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config CRYPTO_ARC4
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tristate "ARC4 cipher algorithm"
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select CRYPTO_BLKCIPHER
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select CRYPTO_LIB_ARC4
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help
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ARC4 cipher algorithm.
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@ -18,33 +18,12 @@
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#include <linux/init.h>
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#include <linux/module.h>
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struct arc4_ctx {
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u32 S[256];
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u32 x, y;
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};
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static int arc4_set_key(struct crypto_tfm *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_tfm_ctx(tfm);
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int i, j = 0, k = 0;
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ctx->x = 1;
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ctx->y = 0;
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for (i = 0; i < 256; i++)
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ctx->S[i] = i;
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for (i = 0; i < 256; i++) {
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u32 a = ctx->S[i];
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j = (j + in_key[k] + a) & 0xff;
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ctx->S[i] = ctx->S[j];
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ctx->S[j] = a;
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if (++k >= key_len)
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k = 0;
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}
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return 0;
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return arc4_setkey(ctx, in_key, key_len);
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}
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static int arc4_set_key_skcipher(struct crypto_skcipher *tfm, const u8 *in_key,
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@ -53,43 +32,6 @@ static int arc4_set_key_skcipher(struct crypto_skcipher *tfm, const u8 *in_key,
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return arc4_set_key(&tfm->base, in_key, key_len);
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}
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static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in,
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unsigned int len)
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{
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u32 *const S = ctx->S;
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u32 x, y, a, b;
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u32 ty, ta, tb;
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if (len == 0)
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return;
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x = ctx->x;
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y = ctx->y;
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a = S[x];
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y = (y + a) & 0xff;
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b = S[y];
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do {
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S[y] = a;
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a = (a + b) & 0xff;
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S[x] = b;
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x = (x + 1) & 0xff;
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ta = S[x];
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ty = (y + ta) & 0xff;
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tb = S[ty];
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*out++ = *in++ ^ S[a];
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if (--len == 0)
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break;
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y = ty;
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a = ta;
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b = tb;
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} while (true);
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ctx->x = x;
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ctx->y = y;
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}
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static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in)
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{
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arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1);
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@ -6,8 +6,18 @@
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#ifndef _CRYPTO_ARC4_H
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#define _CRYPTO_ARC4_H
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#include <linux/types.h>
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#define ARC4_MIN_KEY_SIZE 1
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#define ARC4_MAX_KEY_SIZE 256
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#define ARC4_BLOCK_SIZE 1
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struct arc4_ctx {
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u32 S[256];
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u32 x, y;
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};
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int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len);
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void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len);
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#endif /* _CRYPTO_ARC4_H */
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@ -102,7 +102,7 @@ endif
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obj-$(CONFIG_DEBUG_INFO_REDUCED) += debug_info.o
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CFLAGS_debug_info.o += $(call cc-option, -femit-struct-debug-detailed=any)
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obj-y += math/
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obj-y += math/ crypto/
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obj-$(CONFIG_GENERIC_IOMAP) += iomap.o
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obj-$(CONFIG_GENERIC_PCI_IOMAP) += pci_iomap.o
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@ -0,0 +1,4 @@
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# SPDX-License-Identifier: GPL-2.0
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obj-$(CONFIG_CRYPTO_LIB_ARC4) += libarc4.o
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libarc4-y := arc4.o
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@ -0,0 +1,74 @@
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// 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 <linux/module.h>
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int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len)
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{
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int i, j = 0, k = 0;
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ctx->x = 1;
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ctx->y = 0;
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for (i = 0; i < 256; i++)
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ctx->S[i] = i;
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for (i = 0; i < 256; i++) {
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u32 a = ctx->S[i];
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j = (j + in_key[k] + a) & 0xff;
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ctx->S[i] = ctx->S[j];
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ctx->S[j] = a;
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if (++k >= key_len)
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k = 0;
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}
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return 0;
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}
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EXPORT_SYMBOL(arc4_setkey);
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void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len)
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{
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u32 *const S = ctx->S;
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u32 x, y, a, b;
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u32 ty, ta, tb;
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if (len == 0)
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return;
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x = ctx->x;
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y = ctx->y;
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a = S[x];
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y = (y + a) & 0xff;
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b = S[y];
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do {
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S[y] = a;
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a = (a + b) & 0xff;
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S[x] = b;
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x = (x + 1) & 0xff;
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ta = S[x];
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ty = (y + ta) & 0xff;
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tb = S[ty];
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*out++ = *in++ ^ S[a];
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if (--len == 0)
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break;
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y = ty;
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a = ta;
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b = tb;
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} while (true);
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ctx->x = x;
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ctx->y = y;
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}
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EXPORT_SYMBOL(arc4_crypt);
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MODULE_LICENSE("GPL");
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