crypto: salsa20 - remove Salsa20 stream cipher algorithm

Salsa20 is not used anywhere in the kernel, is not suitable for disk
encryption, and widely considered to have been superseded by ChaCha20.
So let's remove it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by:  Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 212 deletions

diff --git a/crypto/salsa20_generic.c b/crypto/salsa20_generic.c
deleted file mode 100644
index 3418869dabef..000000000000
--- a/crypto/salsa20_generic.c
+++ /dev/null
@@ -1,212 +0,0 @@
-/*
- * Salsa20: Salsa20 stream cipher algorithm
- *
- * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
- *
- * Derived from:
- * - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
- *
- * Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
- * Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
- * More information about eSTREAM and Salsa20 can be found here:
- *   https://www.ecrypt.eu.org/stream/
- *   https://cr.yp.to/snuffle.html
- *
- * 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 <asm/unaligned.h>
-#include <crypto/internal/skcipher.h>
-#include <linux/module.h>
-
-#define SALSA20_IV_SIZE        8
-#define SALSA20_MIN_KEY_SIZE  16
-#define SALSA20_MAX_KEY_SIZE  32
-#define SALSA20_BLOCK_SIZE    64
-
-struct salsa20_ctx {
-	u32 initial_state[16];
-};
-
-static void salsa20_block(u32 *state, __le32 *stream)
-{
-	u32 x[16];
-	int i;
-
-	memcpy(x, state, sizeof(x));
-
-	for (i = 0; i < 20; i += 2) {
-		x[ 4] ^= rol32((x[ 0] + x[12]),  7);
-		x[ 8] ^= rol32((x[ 4] + x[ 0]),  9);
-		x[12] ^= rol32((x[ 8] + x[ 4]), 13);
-		x[ 0] ^= rol32((x[12] + x[ 8]), 18);
-		x[ 9] ^= rol32((x[ 5] + x[ 1]),  7);
-		x[13] ^= rol32((x[ 9] + x[ 5]),  9);
-		x[ 1] ^= rol32((x[13] + x[ 9]), 13);
-		x[ 5] ^= rol32((x[ 1] + x[13]), 18);
-		x[14] ^= rol32((x[10] + x[ 6]),  7);
-		x[ 2] ^= rol32((x[14] + x[10]),  9);
-		x[ 6] ^= rol32((x[ 2] + x[14]), 13);
-		x[10] ^= rol32((x[ 6] + x[ 2]), 18);
-		x[ 3] ^= rol32((x[15] + x[11]),  7);
-		x[ 7] ^= rol32((x[ 3] + x[15]),  9);
-		x[11] ^= rol32((x[ 7] + x[ 3]), 13);
-		x[15] ^= rol32((x[11] + x[ 7]), 18);
-		x[ 1] ^= rol32((x[ 0] + x[ 3]),  7);
-		x[ 2] ^= rol32((x[ 1] + x[ 0]),  9);
-		x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
-		x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
-		x[ 6] ^= rol32((x[ 5] + x[ 4]),  7);
-		x[ 7] ^= rol32((x[ 6] + x[ 5]),  9);
-		x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
-		x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
-		x[11] ^= rol32((x[10] + x[ 9]),  7);
-		x[ 8] ^= rol32((x[11] + x[10]),  9);
-		x[ 9] ^= rol32((x[ 8] + x[11]), 13);
-		x[10] ^= rol32((x[ 9] + x[ 8]), 18);
-		x[12] ^= rol32((x[15] + x[14]),  7);
-		x[13] ^= rol32((x[12] + x[15]),  9);
-		x[14] ^= rol32((x[13] + x[12]), 13);
-		x[15] ^= rol32((x[14] + x[13]), 18);
-	}
-
-	for (i = 0; i < 16; i++)
-		stream[i] = cpu_to_le32(x[i] + state[i]);
-
-	if (++state[8] == 0)
-		state[9]++;
-}
-
-static void salsa20_docrypt(u32 *state, u8 *dst, const u8 *src,
-			    unsigned int bytes)
-{
-	__le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)];
-
-	while (bytes >= SALSA20_BLOCK_SIZE) {
-		salsa20_block(state, stream);
-		crypto_xor_cpy(dst, src, (const u8 *)stream,
-			       SALSA20_BLOCK_SIZE);
-		bytes -= SALSA20_BLOCK_SIZE;
-		dst += SALSA20_BLOCK_SIZE;
-		src += SALSA20_BLOCK_SIZE;
-	}
-	if (bytes) {
-		salsa20_block(state, stream);
-		crypto_xor_cpy(dst, src, (const u8 *)stream, bytes);
-	}
-}
-
-static void salsa20_init(u32 *state, const struct salsa20_ctx *ctx,
-			 const u8 *iv)
-{
-	memcpy(state, ctx->initial_state, sizeof(ctx->initial_state));
-	state[6] = get_unaligned_le32(iv + 0);
-	state[7] = get_unaligned_le32(iv + 4);
-}
-
-static int salsa20_setkey(struct crypto_skcipher *tfm, const u8 *key,
-			  unsigned int keysize)
-{
-	static const char sigma[16] = "expand 32-byte k";
-	static const char tau[16] = "expand 16-byte k";
-	struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
-	const char *constants;
-
-	if (keysize != SALSA20_MIN_KEY_SIZE &&
-	    keysize != SALSA20_MAX_KEY_SIZE)
-		return -EINVAL;
-
-	ctx->initial_state[1] = get_unaligned_le32(key + 0);
-	ctx->initial_state[2] = get_unaligned_le32(key + 4);
-	ctx->initial_state[3] = get_unaligned_le32(key + 8);
-	ctx->initial_state[4] = get_unaligned_le32(key + 12);
-	if (keysize == 32) { /* recommended */
-		key += 16;
-		constants = sigma;
-	} else { /* keysize == 16 */
-		constants = tau;
-	}
-	ctx->initial_state[11] = get_unaligned_le32(key + 0);
-	ctx->initial_state[12] = get_unaligned_le32(key + 4);
-	ctx->initial_state[13] = get_unaligned_le32(key + 8);
-	ctx->initial_state[14] = get_unaligned_le32(key + 12);
-	ctx->initial_state[0]  = get_unaligned_le32(constants + 0);
-	ctx->initial_state[5]  = get_unaligned_le32(constants + 4);
-	ctx->initial_state[10] = get_unaligned_le32(constants + 8);
-	ctx->initial_state[15] = get_unaligned_le32(constants + 12);
-
-	/* space for the nonce; it will be overridden for each request */
-	ctx->initial_state[6] = 0;
-	ctx->initial_state[7] = 0;
-
-	/* initial block number */
-	ctx->initial_state[8] = 0;
-	ctx->initial_state[9] = 0;
-
-	return 0;
-}
-
-static int salsa20_crypt(struct skcipher_request *req)
-{
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
-	struct skcipher_walk walk;
-	u32 state[16];
-	int err;
-
-	err = skcipher_walk_virt(&walk, req, false);
-
-	salsa20_init(state, ctx, req->iv);
-
-	while (walk.nbytes > 0) {
-		unsigned int nbytes = walk.nbytes;
-
-		if (nbytes < walk.total)
-			nbytes = round_down(nbytes, walk.stride);
-
-		salsa20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
-				nbytes);
-		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
-	}
-
-	return err;
-}
-
-static struct skcipher_alg alg = {
-	.base.cra_name		= "salsa20",
-	.base.cra_driver_name	= "salsa20-generic",
-	.base.cra_priority	= 100,
-	.base.cra_blocksize	= 1,
-	.base.cra_ctxsize	= sizeof(struct salsa20_ctx),
-	.base.cra_module	= THIS_MODULE,
-
-	.min_keysize		= SALSA20_MIN_KEY_SIZE,
-	.max_keysize		= SALSA20_MAX_KEY_SIZE,
-	.ivsize			= SALSA20_IV_SIZE,
-	.chunksize		= SALSA20_BLOCK_SIZE,
-	.setkey			= salsa20_setkey,
-	.encrypt		= salsa20_crypt,
-	.decrypt		= salsa20_crypt,
-};
-
-static int __init salsa20_generic_mod_init(void)
-{
-	return crypto_register_skcipher(&alg);
-}
-
-static void __exit salsa20_generic_mod_fini(void)
-{
-	crypto_unregister_skcipher(&alg);
-}
-
-subsys_initcall(salsa20_generic_mod_init);
-module_exit(salsa20_generic_mod_fini);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
-MODULE_ALIAS_CRYPTO("salsa20");
-MODULE_ALIAS_CRYPTO("salsa20-generic");