New on disk format - encryption

1 files changed, 99 insertions, 0 deletions

diff --git a/linux/crypto/chacha20_generic.c b/linux/crypto/chacha20_generic.c
new file mode 100644
index 00000000..7ac68321
--- /dev/null
+++ b/linux/crypto/chacha20_generic.c
@@ -0,0 +1,99 @@
+/*
+ * ChaCha20 256-bit cipher algorithm, 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/byteorder.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/scatterlist.h>
+#include <asm/unaligned.h>
+
+#include <linux/crypto.h>
+#include <crypto/algapi.h>
+#include <crypto/chacha20.h>
+
+#include <sodium/crypto_stream_chacha20.h>
+
+struct chacha20_ctx {
+	u32 key[8];
+};
+
+static int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
+				  unsigned int keysize)
+{
+	struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
+	int i;
+
+	if (keysize != CHACHA20_KEY_SIZE)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
+		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
+
+	return 0;
+}
+
+static int crypto_chacha20_crypt(struct blkcipher_desc *desc,
+				 struct scatterlist *dst,
+				 struct scatterlist *src,
+				 unsigned nbytes)
+{
+	struct chacha20_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
+	struct scatterlist *sg = src;
+	u32 iv[4];
+	int ret;
+
+	BUG_ON(src != dst);
+
+	memcpy(iv, desc->info, sizeof(iv));
+
+	while (1) {
+		ret = crypto_stream_chacha20_xor_ic(sg_virt(sg),
+						    sg_virt(sg),
+						    sg->length,
+						    (void *) &iv[2],
+						    iv[0] | ((u64) iv[1] << 32),
+						    (void *) ctx->key);
+		BUG_ON(ret);
+
+		nbytes -= sg->length;
+
+		if (sg_is_last(sg))
+			break;
+
+		BUG_ON(sg->length % CHACHA20_BLOCK_SIZE);
+		iv[0] += sg->length / CHACHA20_BLOCK_SIZE;
+		sg = sg_next(sg);
+	};
+
+	BUG_ON(nbytes);
+
+	return 0;
+}
+
+static struct crypto_alg alg = {
+	.cra_name		= "chacha20",
+	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
+	.cra_type		= &crypto_blkcipher_type,
+	.cra_ctxsize		= sizeof(struct chacha20_ctx),
+	.cra_u			= {
+		.blkcipher = {
+			.setkey		= crypto_chacha20_setkey,
+			.encrypt	= crypto_chacha20_crypt,
+			.decrypt	= crypto_chacha20_crypt,
+		},
+	},
+};
+
+__attribute__((constructor(110)))
+static int chacha20_generic_mod_init(void)
+{
+	return crypto_register_alg(&alg);
+}