[PATCH v5 6/7] crypto: isolate the chacha20_block function

Stephan Mueller
2016-06-19T16:07:08Z

The chacha20_block function is extracted into its separate C file to
allow it to be used by other callers.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
crypto/Kconfig | 4 +++
crypto/Makefile | 1 +
crypto/chacha20_block.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++
crypto/chacha20_generic.c | 61 ------------------------------------
include/crypto/chacha20.h | 1 +
5 files changed, 85 insertions(+), 61 deletions(-)
create mode 100644 crypto/chacha20_block.c

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 772d430..2822c0f 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1224,9 +1224,13 @@ config CRYPTO_SALSA20_X86_64
The Salsa20 stream cipher algorithm is designed by Daniel J.
Bernstein <djb@cr.yp.to>. See <http://cr.yp.to/snuffle.html>

+config CRYPTO_CHACHA20_BLOCK
+ bool
+
config CRYPTO_CHACHA20
tristate "ChaCha20 cipher algorithm"
select CRYPTO_BLKCIPHER
+ select CRYPTO_CHACHA20_BLOCK
help
ChaCha20 cipher algorithm, RFC7539.

diff --git a/crypto/Makefile b/crypto/Makefile
index f013fac..1b4cc35 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_CRYPTO_ANUBIS) += anubis.o
obj-$(CONFIG_CRYPTO_SEED) += seed.o
obj-$(CONFIG_CRYPTO_SALSA20) += salsa20_generic.o
obj-$(CONFIG_CRYPTO_CHACHA20) += chacha20_generic.o
+obj-$(CONFIG_CRYPTO_CHACHA20_BLOCK) += chacha20_block.o
obj-$(CONFIG_CRYPTO_POLY1305) += poly1305_generic.o
obj-$(CONFIG_CRYPTO_DEFLATE) += deflate.o
obj-$(CONFIG_CRYPTO_MICHAEL_MIC) += michael_mic.o
diff --git a/crypto/chacha20_block.c b/crypto/chacha20_block.c
new file mode 100644
index 0000000..610b391
--- /dev/null
+++ b/crypto/chacha20_block.c
@@ -0,0 +1,79 @@
+/*
+ * ChaCha20 256-bit cipher algorithm, RFC7539
+ *
+ * Copyright (C) 2015 Martin Willi
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/bitops.h>
+#include <linux/cryptohash.h>
+#include <asm/unaligned.h>
+#include <crypto/chacha20.h>
+
+static inline u32 rotl32(u32 v, u8 n)
+{
+ return (v << n) | (v >> (sizeof(v) * 8 - n));
+}
+
+void chacha20_block(u32 *state, void *stream)
+{
+ u32 x[16], *out = stream;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(x); i++)
+ x[i] = state[i];
+
+ for (i = 0; i < 20; i += 2) {
+ x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16);
+ x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16);
+ x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16);
+ x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16);
+
+ x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12);
+ x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12);
+ x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12);
+ x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12);
+
+ x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8);
+ x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8);
+ x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8);
+ x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8);
+
+ x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7);
+ x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7);
+ x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7);
+ x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7);
+
+ x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16);
+ x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16);
+ x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16);
+ x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16);
+
+ x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12);
+ x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12);
+ x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12);
+ x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12);
+
+ x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8);
+ x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8);
+ x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8);
+ x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8);
+
+ x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7);
+ x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7);
+ x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7);
+ x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7);
+ }
+
+ for (i = 0; i < ARRAY_SIZE(x); i++)
+ out[i] = cpu_to_le32(x[i] + state[i]);
+
+ state[12]++;
+}
+EXPORT_SYMBOL(chacha20_block);
diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c
index da9c899..1cab831 100644
--- a/crypto/chacha20_generic.c
+++ b/crypto/chacha20_generic.c
@@ -15,72 +15,11 @@
#include <linux/module.h>
#include <crypto/chacha20.h>

-static inline u32 rotl32(u32 v, u8 n)
-{
- return (v << n) | (v >> (sizeof(v) * 8 - n));
-}
-
static inline u32 le32_to_cpuvp(const void *p)
{
return le32_to_cpup(p);
}

-static void chacha20_block(u32 *state, void *stream)
-{
- u32 x[16], *out = stream;
- int i;
-
- for (i = 0; i < ARRAY_SIZE(x); i++)
- x[i] = state[i];
-
- for (i = 0; i < 20; i += 2) {
- x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16);
- x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16);
- x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16);
- x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16);
-
- x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12);
- x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12);
- x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12);
- x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12);
-
- x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8);
- x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8);
- x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8);
- x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8);
-
- x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7);
- x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7);
- x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7);
- x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7);
-
- x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16);
- x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16);
- x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16);
- x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16);
-
- x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12);
- x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12);
- x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12);
- x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12);
-
- x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8);
- x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8);
- x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8);
- x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8);
-
- x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7);
- x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7);
- x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7);
- x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7);
- }
-
- for (i = 0; i < ARRAY_SIZE(x); i++)
- out[i] = cpu_to_le32(x[i] + state[i]);
-
- state[12]++;
-}
-
static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h
index 274bbae..20d20f68 100644
--- a/include/crypto/chacha20.h
+++ b/include/crypto/chacha20.h
@@ -16,6 +16,7 @@ struct chacha20_ctx {
u32 key[8];
};

+void chacha20_block(u32 *state, void *stream);
void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv);
int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keysize);
--
2.5.5