From a36c71ecb6840ff799546ccaf665e55f6a6ed5dc Mon Sep 17 00:00:00 2001
From: weidai <weidai@57ff6487-cd31-0410-9ec3-f628ee90f5f0>
Date: Thu, 12 Mar 2009 11:24:12 +0000
Subject: - add EAX mode, XSalsa20 - speed up GCM key setup - wipe stack in AES
 assembly code - speed up CFB mode

git-svn-id: svn://svn.code.sf.net/p/cryptopp/code/trunk/c5@444 57ff6487-cd31-0410-9ec3-f628ee90f5f0
---
 modes.cpp | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

(limited to 'modes.cpp')

diff --git a/modes.cpp b/modes.cpp
index cd7450f..81bf4de 100644
--- a/modes.cpp
+++ b/modes.cpp
@@ -24,6 +24,55 @@ void Modes_TestInstantiations()
 }
 #endif
 
+void CFB_ModePolicy::Iterate(byte *output, const byte *input, CipherDir dir, size_t iterationCount)
+{
+	assert(m_cipher->IsForwardTransformation());	// CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
+	assert(m_feedbackSize == BlockSize());
+
+	unsigned int s = BlockSize();
+	if (dir == ENCRYPTION)
+	{
+		m_cipher->ProcessAndXorBlock(m_register, input, output);
+		m_cipher->AdvancedProcessBlocks(output, input+s, output+s, (iterationCount-1)*s, 0);
+		memcpy(m_register, output+(iterationCount-1)*s, s);
+	}
+	else
+	{
+		memcpy(m_temp, input+(iterationCount-1)*s, s);	// make copy first in case of in-place decryption
+		m_cipher->AdvancedProcessBlocks(input, input+s, output+s, (iterationCount-1)*s, BlockTransformation::BT_ReverseDirection);
+		m_cipher->ProcessAndXorBlock(m_register, input, output);
+		memcpy(m_register, m_temp, s);
+	}
+}
+
+void CFB_ModePolicy::TransformRegister()
+{
+	assert(m_cipher->IsForwardTransformation());	// CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
+	m_cipher->ProcessBlock(m_register, m_temp);
+	unsigned int updateSize = BlockSize()-m_feedbackSize;
+	memmove_s(m_register, m_register.size(), m_register+m_feedbackSize, updateSize);
+	memcpy_s(m_register+updateSize, m_register.size()-updateSize, m_temp, m_feedbackSize);
+}
+
+void CFB_ModePolicy::CipherResynchronize(const byte *iv, size_t length)
+{
+	memcpy_s(m_register, m_register.size(), iv, BlockSize());
+	TransformRegister();
+}
+
+void CFB_ModePolicy::SetFeedbackSize(unsigned int feedbackSize)
+{
+	if (feedbackSize > BlockSize())
+		throw InvalidArgument("CFB_Mode: invalid feedback size");
+	m_feedbackSize = feedbackSize ? feedbackSize : BlockSize();
+}
+
+void CFB_ModePolicy::ResizeBuffers()
+{
+	CipherModeBase::ResizeBuffers();
+	m_temp.New(BlockSize());
+}
+
 void OFB_ModePolicy::WriteKeystream(byte *keystreamBuffer, size_t iterationCount)
 {
 	assert(m_cipher->IsForwardTransformation());	// OFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
-- 
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