[CRYPTO] salsa20_i586: Salsa20 stream cipher algorithm (i586 version)

This patch contains the salsa20-i586 implementation. The original
assembly code came from
<http://cr.yp.to/snuffle/salsa20/x86-pm/salsa20.s>. I have reformatted
it (added indents) so that it matches the other algorithms in
arch/x86/crypto.

Signed-off-by: Tan Swee Heng <thesweeheng@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 127 insertions, 0 deletions

diff --git a/arch/x86/crypto/salsa20_glue.c b/arch/x86/crypto/salsa20_glue.c
new file mode 100644
index 000000000000..3be443995ed6
--- /dev/null
+++ b/arch/x86/crypto/salsa20_glue.c
@@ -0,0 +1,127 @@
+/*
+ * Glue code for optimized assembly version of  Salsa20.
+ *
+ * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
+ *
+ * The assembly codes are public domain assembly codes written by Daniel. J.
+ * Bernstein <djb@cr.yp.to>. The codes are modified to include indentation
+ * and to remove extraneous comments and functions that are not needed.
+ * - i586 version, renamed as salsa20-i586-asm_32.S
+ *   available from <http://cr.yp.to/snuffle/salsa20/x86-pm/salsa20.s>
+ *
+ * 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 <crypto/algapi.h>
+#include <linux/module.h>
+#include <linux/crypto.h>
+
+#define SALSA20_IV_SIZE        8U
+#define SALSA20_MIN_KEY_SIZE  16U
+#define SALSA20_MAX_KEY_SIZE  32U
+
+// use the ECRYPT_* function names
+#define salsa20_keysetup        ECRYPT_keysetup
+#define salsa20_ivsetup         ECRYPT_ivsetup
+#define salsa20_encrypt_bytes   ECRYPT_encrypt_bytes
+
+struct salsa20_ctx
+{
+        u32 input[16];
+};
+
+asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
+                                 u32 keysize, u32 ivsize);
+asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
+asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
+                                      const u8 *src, u8 *dst, u32 bytes);
+
+static int setkey(struct crypto_tfm *tfm, const u8 *key,
+                  unsigned int keysize)
+{
+        struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
+        salsa20_keysetup(ctx, key, keysize*8, SALSA20_IV_SIZE*8);
+        return 0;
+}
+
+static int encrypt(struct blkcipher_desc *desc,
+                   struct scatterlist *dst, struct scatterlist *src,
+                   unsigned int nbytes)
+{
+        struct blkcipher_walk walk;
+        struct crypto_blkcipher *tfm = desc->tfm;
+        struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        int err;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+        err = blkcipher_walk_virt_block(desc, &walk, 64);
+
+        salsa20_ivsetup(ctx, walk.iv);
+
+        if (likely(walk.nbytes == nbytes))
+        {
+                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
+                                      walk.dst.virt.addr, nbytes);
+                return blkcipher_walk_done(desc, &walk, 0);
+        }
+
+        while (walk.nbytes >= 64) {
+                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
+                                      walk.dst.virt.addr,
+                                      walk.nbytes - (walk.nbytes % 64));
+                err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
+        }
+
+        if (walk.nbytes) {
+                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
+                                      walk.dst.virt.addr, walk.nbytes);
+                err = blkcipher_walk_done(desc, &walk, 0);
+        }
+
+        return err;
+}
+
+static struct crypto_alg alg = {
+        .cra_name           =   "salsa20",
+        .cra_driver_name    =   "salsa20-asm",
+        .cra_priority       =   200,
+        .cra_flags          =   CRYPTO_ALG_TYPE_BLKCIPHER,
+        .cra_type           =   &crypto_blkcipher_type,
+        .cra_blocksize      =   1,
+        .cra_ctxsize        =   sizeof(struct salsa20_ctx),
+        .cra_alignmask      =   3,
+        .cra_module         =   THIS_MODULE,
+        .cra_list           =   LIST_HEAD_INIT(alg.cra_list),
+        .cra_u              =   {
+                .blkcipher = {
+                        .setkey         =   setkey,
+                        .encrypt        =   encrypt,
+                        .decrypt        =   encrypt,
+                        .min_keysize    =   SALSA20_MIN_KEY_SIZE,
+                        .max_keysize    =   SALSA20_MAX_KEY_SIZE,
+                        .ivsize         =   SALSA20_IV_SIZE,
+                }
+        }
+};
+
+static int __init init(void)
+{
+        return crypto_register_alg(&alg);
+}
+
+static void __exit fini(void)
+{
+        crypto_unregister_alg(&alg);
+}
+
+module_init(init);
+module_exit(fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
+MODULE_ALIAS("salsa20");
+MODULE_ALIAS("salsa20-asm");