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authorArd Biesheuvel <ardb@kernel.org>2019-11-08 15:22:08 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2019-11-17 04:02:39 +0300
commit5fb8ef25803ef33e2eb60b626435828b937bed75 (patch)
tree156401ad072c1acc18f74cbdf8eb31859191b9ac /lib/crypto/libchacha.c
parent746b2e024c67aa605ac12d135cd7085a49cf9dc4 (diff)
downloadlinux-5fb8ef25803ef33e2eb60b626435828b937bed75.tar.xz
crypto: chacha - move existing library code into lib/crypto
Currently, our generic ChaCha implementation consists of a permute function in lib/chacha.c that operates on the 64-byte ChaCha state directly [and which is always included into the core kernel since it is used by the /dev/random driver], and the crypto API plumbing to expose it as a skcipher. In order to support in-kernel users that need the ChaCha streamcipher but have no need [or tolerance] for going through the abstractions of the crypto API, let's expose the streamcipher bits via a library API as well, in a way that permits the implementation to be superseded by an architecture specific one if provided. So move the streamcipher code into a separate module in lib/crypto, and expose the init() and crypt() routines to users of the library. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'lib/crypto/libchacha.c')
-rw-r--r--lib/crypto/libchacha.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/lib/crypto/libchacha.c b/lib/crypto/libchacha.c
new file mode 100644
index 000000000000..dabc3accae05
--- /dev/null
+++ b/lib/crypto/libchacha.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The ChaCha stream cipher (RFC7539)
+ *
+ * Copyright (C) 2015 Martin Willi
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/module.h>
+
+#include <crypto/algapi.h> // for crypto_xor_cpy
+#include <crypto/chacha.h>
+
+void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
+ unsigned int bytes, int nrounds)
+{
+ /* aligned to potentially speed up crypto_xor() */
+ u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
+
+ while (bytes >= CHACHA_BLOCK_SIZE) {
+ chacha_block_generic(state, stream, nrounds);
+ crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
+ bytes -= CHACHA_BLOCK_SIZE;
+ dst += CHACHA_BLOCK_SIZE;
+ src += CHACHA_BLOCK_SIZE;
+ }
+ if (bytes) {
+ chacha_block_generic(state, stream, nrounds);
+ crypto_xor_cpy(dst, src, stream, bytes);
+ }
+}
+EXPORT_SYMBOL(chacha_crypt_generic);
+
+MODULE_LICENSE("GPL");