crypto: chacha20-generic - refactor to allow varying number of rounds

In preparation for adding XChaCha12 support, rename/refactor
chacha20-generic to support different numbers of rounds.  The
justification for needing XChaCha12 support is explained in more detail
in the patch "crypto: chacha - add XChaCha12 support".

The only difference between ChaCha{8,12,20} are the number of rounds
itself; all other parts of the algorithm are the same.  Therefore,
remove the "20" from all definitions, structures, functions, files, etc.
that will be shared by all ChaCha versions.

Also make ->setkey() store the round count in the chacha_ctx (previously
chacha20_ctx).  The generic code then passes the round count through to
chacha_block().  There will be a ->setkey() function for each explicitly
allowed round count; the encrypt/decrypt functions will be the same.  I
decided not to do it the opposite way (same ->setkey() function for all
round counts, with different encrypt/decrypt functions) because that
would have required more boilerplate code in architecture-specific
implementations of ChaCha and XChaCha.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 112 deletions

diff --git a/lib/chacha20.c b/lib/chacha20.c
deleted file mode 100644
index 6a484e16171d..000000000000
--- a/lib/chacha20.c
+++ /dev/null
@@ -1,112 +0,0 @@
-/*
- * The "hash function" used as the core of the ChaCha20 stream cipher (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 void chacha20_permute(u32 *x)
-{
-	int i;
-
-	for (i = 0; i < 20; 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);
-	}
-}
-
-/**
- * chacha20_block - generate one keystream block and increment block counter
- * @state: input state matrix (16 32-bit words)
- * @stream: output keystream block (64 bytes)
- *
- * This is the ChaCha20 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 chacha20_block(u32 *state, u8 *stream)
-{
-	u32 x[16];
-	int i;
-
-	memcpy(x, state, 64);
-
-	chacha20_permute(x);
-
-	for (i = 0; i < ARRAY_SIZE(x); i++)
-		put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
-
-	state[12]++;
-}
-EXPORT_SYMBOL(chacha20_block);
-
-/**
- * hchacha20_block - abbreviated ChaCha20 core, for XChaCha20
- * @in: input state matrix (16 32-bit words)
- * @out: output (8 32-bit words)
- *
- * HChaCha20 is the ChaCha equivalent of HSalsa20 and is an intermediate step
- * towards XChaCha20 (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf).
- * HChaCha20 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 hchacha20_block(const u32 *in, u32 *out)
-{
-	u32 x[16];
-
-	memcpy(x, in, 64);
-
-	chacha20_permute(x);
-
-	memcpy(&out[0], &x[0], 16);
-	memcpy(&out[4], &x[12], 16);
-}
-EXPORT_SYMBOL(hchacha20_block);