From 10276f8a3f90da78ca1de7ec3be05dfc85d29a13 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Thu, 6 Sep 2001 23:45:44 +0200
Subject: [PATCH] * cbc.c, cbc.h: New files, for general CBC encryption.
Rev: src/nettle/cbc.c:1.1
Rev: src/nettle/cbc.h:1.1
---
cbc.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
cbc.h | 49 +++++++++++++++++++++++++++++++++++++
2 files changed, 127 insertions(+)
create mode 100644 cbc.c
create mode 100644 cbc.h
diff --git a/cbc.c b/cbc.c
new file mode 100644
index 00000000..768ba1db
--- /dev/null
+++ b/cbc.c
@@ -0,0 +1,78 @@
+/* cbc.c
+ *
+ * Cipher block chaining mode.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2001 Niels Möller
+ *
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ *
+ * The nettle library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#include "cbc.h"
+
+#include <assert.h>
+
+void
+cbc_encrypt(void *ctx, void (*f)(void *ctx,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src),
+ unsigned block_size, uint8_t *iv,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src)
+{
+ assert(!(length % block_size));
+
+ for ( ; length; length -= block_size, src += block_size, dst += block_size)
+ {
+ memxor(iv, src, block_size);
+ f(ctx, dst, src, block_size);
+ memcpy(iv, dst, block_size);
+ }
+}
+
+void
+cbc_decrypt(void *ctx, void (*f)(void *ctx,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src),
+ unsigned block_size, uint8_t *iv,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src)
+{
+ assert(!(length % block_size));
+
+ if (!length)
+ return;
+
+ if (src == dst)
+ {
+ /* Keep a copy of the ciphertext. */
+ /* FIXME: If length is large enough, allocate a smaller buffer
+ * and process one buffer size at a time */
+ uint8_t *tmp = alloca(length);
+ memcpy(tmp, src, length);
+ src = tmp;
+ }
+
+ /* Decrypt in ECB mode */
+ f(ctx, dst, src, length);
+
+ /* XOR the cryptotext, shifted one block */
+ memxor(dst, iv, block_size);
+ memxor(dst + block_size, src, length - block_size);
+ memcpy(iv, src + length - block_size, block_size);
+}
diff --git a/cbc.h b/cbc.h
new file mode 100644
index 00000000..4335a518
--- /dev/null
+++ b/cbc.h
@@ -0,0 +1,49 @@
+/* cbc.h
+ *
+ * Cipher block chaining mode.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2001 Niels Möller
+ *
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ *
+ * The nettle library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#ifndef NETTLE_CBC_H_INCLUDED
+#define NETTLE_CBC_H_INCLUDED
+
+#include <inttypes.h>
+
+/* Uses a void * for cipher contexts. It's hard to be type safe. */
+
+void
+cbc_encrypt(void *ctx, void (*f)(void *ctx,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src),
+ unsigned block_size, uint8_t *iv,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src);
+
+void
+cbc_decrypt(void *ctx, void (*f)(void *ctx,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src),
+ unsigned block_size, uint8_t *iv,
+ unsigned length, uint8_t *dst,
+ const uint8_t *src);
+
+#endif /* NETTLE_CBC_H_INCLUDED */
--
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