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as well, in a way that permits the implementation to be superseded by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>

1 files changed, 0 insertions, 113 deletions

diff --git a/lib/chacha.c b/lib/chacha.c
deleted file mode 100644
index c7c9826564d3..000000000000
--- a/lib/chacha.c
+++ /dev/null
@@ -1,113 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * The "hash function" used as the core of the ChaCha stream cipher (RFC7539)
- *
- * Copyright (C) 2015 Martin Willi
- */
-
-#include <linux/kernel.h>
-#include <linux/export.h>
-#include <linux/bitops.h>
-#include <linux/cryptohash.h>
-#include <asm/unaligned.h>
-#include <crypto/chacha.h>
-
-static void chacha_permute(u32 *x, int nrounds)
-{
-	int i;
-
-	/* whitelist the allowed round counts */
-	WARN_ON_ONCE(nrounds != 20 && nrounds != 12);
-
-	for (i = 0; i < nrounds; i += 2) {
-		x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],  16);
-		x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],  16);
-		x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],  16);
-		x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],  16);
-
-		x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],  12);
-		x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],  12);
-		x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10], 12);
-		x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11], 12);
-
-		x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],   8);
-		x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],   8);
-		x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],   8);
-		x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],   8);
-
-		x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],   7);
-		x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],   7);
-		x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10],  7);
-		x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11],  7);
-
-		x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],  16);
-		x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],  16);
-		x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],  16);
-		x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],  16);
-
-		x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10], 12);
-		x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11], 12);
-		x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],  12);
-		x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],  12);
-
-		x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],   8);
-		x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],   8);
-		x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],   8);
-		x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],   8);
-
-		x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10],  7);
-		x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11],  7);
-		x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],   7);
-		x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],   7);
-	}
-}
-
-/**
- * chacha_block - generate one keystream block and increment block counter
- * @state: input state matrix (16 32-bit words)
- * @stream: output keystream block (64 bytes)
- * @nrounds: number of rounds (20 or 12; 20 is recommended)
- *
- * This is the ChaCha core, a function from 64-byte strings to 64-byte strings.
- * The caller has already converted the endianness of the input.  This function
- * also handles incrementing the block counter in the input matrix.
- */
-void chacha_block(u32 *state, u8 *stream, int nrounds)
-{
-	u32 x[16];
-	int i;
-
-	memcpy(x, state, 64);
-
-	chacha_permute(x, nrounds);
-
-	for (i = 0; i < ARRAY_SIZE(x); i++)
-		put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
-
-	state[12]++;
-}
-EXPORT_SYMBOL(chacha_block);
-
-/**
- * hchacha_block - abbreviated ChaCha core, for XChaCha
- * @in: input state matrix (16 32-bit words)
- * @out: output (8 32-bit words)
- * @nrounds: number of rounds (20 or 12; 20 is recommended)
- *
- * HChaCha is the ChaCha equivalent of HSalsa and is an intermediate step
- * towards XChaCha (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf).  HChaCha
- * skips the final addition of the initial state, and outputs only certain words
- * of the state.  It should not be used for streaming directly.
- */
-void hchacha_block(const u32 *in, u32 *out, int nrounds)
-{
-	u32 x[16];
-
-	memcpy(x, in, 64);
-
-	chacha_permute(x, nrounds);
-
-	memcpy(&out[0], &x[0], 16);
-	memcpy(&out[4], &x[12], 16);
-}
-EXPORT_SYMBOL(hchacha_block);