First Commit

externals/cryptopp/arc4.cpp

@@ -0,0 +1,122 @@
+// arc4.cpp - originally written and placed in the public domain by Wei Dai
+
+// The ARC4 algorithm was first revealed in an anonymous email to the
+// cypherpunks mailing list. This file originally contained some
+// code copied from this email. The code has since been rewritten in order
+// to clarify the copyright status of this file. It should now be
+// completely in the public domain.
+
+#include "pch.h"
+#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
+#include "arc4.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+namespace Weak1 {
+
+#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
+void ARC4_TestInstantiations()
+{
+	ARC4 x;
+}
+#endif
+
+ARC4_Base::~ARC4_Base()
+{
+	m_x = m_y = 0;
+}
+
+void ARC4_Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
+{
+	AssertValidKeyLength(length);
+
+	m_x = 1;
+	m_y = 0;
+
+	unsigned int i;
+	for (i=0; i<256; i++)
+		m_state[i] = byte(i);
+
+	unsigned int keyIndex = 0, stateIndex = 0;
+	for (i=0; i<256; i++)
+	{
+		unsigned int a = m_state[i];
+		stateIndex += key[keyIndex] + a;
+		stateIndex &= 0xff;
+		m_state[i] = m_state[stateIndex];
+		m_state[stateIndex] = byte(a);
+		if (++keyIndex >= length)
+			keyIndex = 0;
+	}
+
+	int discardBytes = params.GetIntValueWithDefault("DiscardBytes", GetDefaultDiscardBytes());
+	DiscardBytes(discardBytes);
+}
+
+template <class T>
+static inline unsigned int MakeByte(T &x, T &y, byte *s)
+{
+	unsigned int a = s[x];
+	y = byte((y+a) & 0xff);
+	unsigned int b = s[y];
+	s[x] = byte(b);
+	s[y] = byte(a);
+	x = byte((x+1) & 0xff);
+	return s[(a+b) & 0xff];
+}
+
+void ARC4_Base::GenerateBlock(byte *output, size_t size)
+{
+	while (size--)
+		*output++ = static_cast<byte>(MakeByte(m_x, m_y, m_state));
+}
+
+void ARC4_Base::ProcessData(byte *outString, const byte *inString, size_t length)
+{
+	if (length == 0)
+		return;
+
+	byte *const s = m_state;
+	unsigned int x = m_x;
+	unsigned int y = m_y;
+
+	if (inString == outString)
+	{
+		do
+		{
+			*outString++ ^= MakeByte(x, y, s);
+		} while (--length);
+	}
+	else
+	{
+		do
+		{
+			*outString++ = *inString++ ^ byte(MakeByte(x, y, s));
+		}
+		while(--length);
+	}
+
+	m_x = byte(x);
+	m_y = byte(y);
+}
+
+void ARC4_Base::DiscardBytes(size_t n)
+{
+	if (n == 0)
+		return;
+
+	byte *const s = m_state;
+	unsigned int x = m_x;
+	unsigned int y = m_y;
+
+	do
+	{
+		MakeByte(x, y, s);
+	}
+	while(--n);
+
+	m_x = byte(x);
+	m_y = byte(y);
+}
+
+}
+NAMESPACE_END