From: rasky <rasky@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Wed, 29 Sep 2010 16:35:39 +0000 (+0000)
Subject: SEC: extract the CTR step into a public function, for algorithms that might use it.
X-Git-Tag: 2.6.0~42
X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=20491f5ce0cb9b92b33e52d1d1015930618b00e8;p=bertos.git

SEC: extract the CTR step into a public function, for algorithms that might use it.


git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4359 38d2e660-2303-0410-9eaa-f027e97ec537
---

diff --git a/bertos/sec/cipher.c b/bertos/sec/cipher.c
index 22bebe60..7977cc46 100644
--- a/bertos/sec/cipher.c
+++ b/bertos/sec/cipher.c
@@ -64,16 +64,21 @@ static void ctr_increment(void *buf, size_t len)
 			return;
 }
 
+void cipher_ctr_step(BlockCipher *c, void *block)
+{
+	memcpy(block, c->buf, c->block_len);
+	c->enc_block(c, block);
+	ctr_increment(c->buf, c->block_len);
+}
+
 void cipher_ctr_encrypt(BlockCipher *c, void *block)
 {
 	uint8_t temp[c->block_len];
 
-	memcpy(temp, c->buf, c->block_len);
-	c->enc_block(c, temp);
+	cipher_ctr_step(c, temp);
 	xor_block(block, block, temp, c->block_len);
 
 	PURGE(temp);
-	ctr_increment(c->buf, c->block_len);
 }
 
 void cipher_ctr_decrypt(BlockCipher *c, void *block)
diff --git a/bertos/sec/cipher.h b/bertos/sec/cipher.h
index f0f37a36..f67cb809 100644
--- a/bertos/sec/cipher.h
+++ b/bertos/sec/cipher.h
@@ -149,13 +149,23 @@ INLINE void cipher_ctr_begin(BlockCipher *c, void *counter)
 }
 
 /**
- * Encrypt a block (in-place) using the current key in CBC mode.
+ * Encrypt a block (in-place) using the current key in CTR mode.
  */
 void cipher_ctr_encrypt(BlockCipher *c, void *block);
 
 /**
- * Decrypt a block (in-place) using the current key in CBC mode.
+ * Decrypt a block (in-place) using the current key in CTR mode.
  */
 void cipher_ctr_decrypt(BlockCipher *c, void *block);
 
+/**
+ * Generate the crypted stream block in CTR mode for the current
+ * counter, and then bump it.
+ *
+ * This function is basically the core CTR operation, without the final
+ * XOR pass with the plaintext or ciphertext. For normal CTR usage,
+ * you never need to call it.
+ */
+void cipher_ctr_step(BlockCipher *c, void *block);
+
 #endif /* SEC_CIPHER_H */