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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2019-06-12 18:19:53 +0200 |
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committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-06-20 14:18:33 +0800 |
commit | dc51f25752bfcb5f1edbac1ca4ce16af7b3bd507 (patch) | |
tree | 063eb09177d3abc17deaaae732dd011592f5f573 /lib/crypto | |
parent | 192125ed5ce62afba24312d8e7a0314577565b4a (diff) | |
download | lwn-dc51f25752bfcb5f1edbac1ca4ce16af7b3bd507.tar.gz lwn-dc51f25752bfcb5f1edbac1ca4ce16af7b3bd507.zip |
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>
Diffstat (limited to 'lib/crypto')
-rw-r--r-- | lib/crypto/Makefile | 4 | ||||
-rw-r--r-- | lib/crypto/arc4.c | 74 |
2 files changed, 78 insertions, 0 deletions
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile new file mode 100644 index 000000000000..88195c34932d --- /dev/null +++ b/lib/crypto/Makefile @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_CRYPTO_LIB_ARC4) += libarc4.o +libarc4-y := arc4.o diff --git a/lib/crypto/arc4.c b/lib/crypto/arc4.c new file mode 100644 index 000000000000..c2020f19c652 --- /dev/null +++ b/lib/crypto/arc4.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Cryptographic API + * + * ARC4 Cipher Algorithm + * + * Jon Oberheide <jon@oberheide.org> + */ + +#include <crypto/arc4.h> +#include <linux/module.h> + +int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len) +{ + int i, j = 0, k = 0; + + ctx->x = 1; + ctx->y = 0; + + for (i = 0; i < 256; i++) + ctx->S[i] = i; + + for (i = 0; i < 256; i++) { + u32 a = ctx->S[i]; + + j = (j + in_key[k] + a) & 0xff; + ctx->S[i] = ctx->S[j]; + ctx->S[j] = a; + if (++k >= key_len) + k = 0; + } + + return 0; +} +EXPORT_SYMBOL(arc4_setkey); + +void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len) +{ + u32 *const S = ctx->S; + u32 x, y, a, b; + u32 ty, ta, tb; + + if (len == 0) + return; + + x = ctx->x; + y = ctx->y; + + a = S[x]; + y = (y + a) & 0xff; + b = S[y]; + + do { + S[y] = a; + a = (a + b) & 0xff; + S[x] = b; + x = (x + 1) & 0xff; + ta = S[x]; + ty = (y + ta) & 0xff; + tb = S[ty]; + *out++ = *in++ ^ S[a]; + if (--len == 0) + break; + y = ty; + a = ta; + b = tb; + } while (true); + + ctx->x = x; + ctx->y = y; +} +EXPORT_SYMBOL(arc4_crypt); + +MODULE_LICENSE("GPL"); |