From 79243bffdd9b63204a45fba6268d1d48f4c37dfe Mon Sep 17 00:00:00 2001
From: rasky <rasky@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Mon, 4 Oct 2010 18:43:14 +0000
Subject: [PATCH] SEC: add OFB mode to symmetric ciphers.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4401 38d2e660-2303-0410-9eaa-f027e97ec537
---
 bertos/sec/cipher.c | 16 ++++++++++++++++
 bertos/sec/cipher.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/bertos/sec/cipher.c b/bertos/sec/cipher.c
index 7977cc46..ba4ae981 100644
--- a/bertos/sec/cipher.c
+++ b/bertos/sec/cipher.c
@@ -85,3 +85,19 @@ void cipher_ctr_decrypt(BlockCipher *c, void *block)
 {
 	cipher_ctr_encrypt(c, block);
 }
+
+static void ofb_step(BlockCipher *c)
+{
+	c->enc_block(c, c->buf);
+}
+
+void cipher_ofb_encrypt(BlockCipher *c, void *block)
+{
+	ofb_step(c);
+	xor_block(block, block, c->buf, c->block_len);
+}
+
+void cipher_ofb_decrypt(BlockCipher *c, void *block)
+{
+	cipher_ofb_encrypt(c, block);
+}
diff --git a/bertos/sec/cipher.h b/bertos/sec/cipher.h
index 24c24b0d..845a32d2 100644
--- a/bertos/sec/cipher.h
+++ b/bertos/sec/cipher.h
@@ -188,4 +188,32 @@ void cipher_ctr_decrypt(BlockCipher *c, void *block);
  */
 void cipher_ctr_step(BlockCipher *c, void *block);
 
+
+/*********************************************************************************/
+/* OFB mode                                                                      */
+/*********************************************************************************/
+
+/**
+ * Initialize OFB by setting the IV.
+ *
+ * \note the memory pointed by \a iv will be used and modified by the CBC
+ * functions. It is caller's responsibility to keep it available until there is
+ * no more OFB work to do.
+ */
+INLINE void cipher_ofb_begin(BlockCipher *c, void *iv)
+{
+	c->buf = iv;
+}
+
+/**
+ * Encrypt a block (in-place) using the current key in OFB mode.
+ */
+void cipher_ofb_encrypt(BlockCipher *c, void *block);
+
+/**
+ * Decrypt a block (in-place) using the current key in OFB mode.
+ */
+void cipher_ofb_decrypt(BlockCipher *c, void *block);
+
+
 #endif /* SEC_CIPHER_H */
-- 
2.25.1