From e553818e00684e8905ede16e53aa490c153b7e7a Mon Sep 17 00:00:00 2001
From: weidai <weidai@57ff6487-cd31-0410-9ec3-f628ee90f5f0>
Date: Sat, 9 Dec 2006 17:18:13 +0000
Subject: add Salsa20 cipher

git-svn-id: svn://svn.code.sf.net/p/cryptopp/code/trunk/c5@247 57ff6487-cd31-0410-9ec3-f628ee90f5f0
---
 salsa.cpp | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100755 salsa.cpp

(limited to 'salsa.cpp')

diff --git a/salsa.cpp b/salsa.cpp
new file mode 100755
index 0000000..a3c18ef
--- /dev/null
+++ b/salsa.cpp
@@ -0,0 +1,139 @@
+// salsa.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "salsa.h"
+#include "misc.h"
+#include "argnames.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+void Salsa20_TestInstantiations()
+{
+	Salsa20::Encryption x;
+}
+
+void Salsa20_Policy::GetNextIV(byte *IV) const
+{
+	word32 j6 = m_state[6] + 1;
+	word32 j7 = m_state[7] + (j6 == 0);
+
+	UnalignedPutWord(LITTLE_ENDIAN_ORDER, IV, j6);
+	UnalignedPutWord(LITTLE_ENDIAN_ORDER, IV+4, j7);
+}
+
+void Salsa20_Policy::CipherSetKey(const NameValuePairs &params, const byte *key, size_t length)
+{
+	m_rounds = params.GetIntValueWithDefault(Name::Rounds(), 20);
+
+	if (!(m_rounds == 8 || m_rounds == 12 || m_rounds == 20))
+		throw InvalidRounds(StaticAlgorithmName(), m_rounds);
+
+	GetUserKey(LITTLE_ENDIAN_ORDER, m_state+1, 4, key, 16);
+	GetUserKey(LITTLE_ENDIAN_ORDER, m_state+11, 4, key + length - 16, 16);
+
+	// m_state[0,5,10,15] forms "expand 16-byte k" or "expand 32-byte k"
+	m_state[0] = 0x61707865;
+	m_state[5] = (length == 16) ? 0x3120646e : 0x3320646e;
+	m_state[10] = (length == 16) ? 0x79622d36 : 0x79622d32;
+	m_state[15] = 0x6b206574;
+}
+
+void Salsa20_Policy::CipherResynchronize(byte *keystreamBuffer, const byte *IV)
+{
+	GetUserKey(LITTLE_ENDIAN_ORDER, m_state+6, 4, IV, 8);
+}
+
+void Salsa20_Policy::SeekToIteration(lword iterationCount)
+{
+	m_state[8] = (word32)iterationCount;
+	m_state[9] = (word32)SafeRightShift<32>(iterationCount);
+}
+
+void Salsa20_Policy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
+{
+	KeystreamOutput<LittleEndian> keystreamOutput(operation, output, input);
+
+	word32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
+	word32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
+
+	j0 = m_state[0];
+	j1 = m_state[1];
+	j2 = m_state[2];
+	j3 = m_state[3];
+	j4 = m_state[4];
+	j5 = m_state[5];
+	j6 = m_state[6];
+	j7 = m_state[7];
+	j8 = m_state[8];
+	j9 = m_state[9];
+	j10 = m_state[10];
+	j11 = m_state[11];
+	j12 = m_state[12];
+	j13 = m_state[13];
+	j14 = m_state[14];
+	j15 = m_state[15];
+
+	for (size_t iteration = 0; iteration < iterationCount; ++iteration)
+	{
+		x0 = j0;
+		x1 = j1;
+		x2 = j2;
+		x3 = j3;
+		x4 = j4;
+		x5 = j5;
+		x6 = j6;
+		x7 = j7;
+		x8 = j8;
+		x9 = j9;
+		x10 = j10;
+		x11 = j11;
+		x12 = j12;
+		x13 = j13;
+		x14 = j14;
+		x15 = j15;
+
+		for (int i=m_rounds; i>0; i-=2)
+		{
+#define QUARTER_ROUND(a, b, c, d)	\
+	b = b ^ rotlFixed(a + d, 7);	\
+	c = c ^ rotlFixed(b + a, 9);	\
+	d = d ^ rotlFixed(c + b, 13);	\
+	a = a ^ rotlFixed(d + c, 18);
+
+			QUARTER_ROUND(x0, x4, x8, x12)
+			QUARTER_ROUND(x5, x9, x13, x1)
+			QUARTER_ROUND(x10, x14, x2, x6)
+			QUARTER_ROUND(x15, x3, x7, x11)
+
+			QUARTER_ROUND(x0, x1, x2, x3)
+			QUARTER_ROUND(x5, x6, x7, x4)
+			QUARTER_ROUND(x10, x11, x8, x9)
+			QUARTER_ROUND(x15, x12, x13, x14)
+		}
+
+		keystreamOutput	(x0 + j0)
+						(x1 + j1)
+						(x2 + j2)
+						(x3 + j3)
+						(x4 + j4)
+						(x5 + j5)
+						(x6 + j6)
+						(x7 + j7)
+						(x8 + j8)
+						(x9 + j9)
+						(x10 + j10)
+						(x11 + j11)
+						(x12 + j12)
+						(x13 + j13)
+						(x14 + j14)
+						(x15 + j15);
+
+		if (++j8 == 0)
+			++j9;
+	}
+
+	m_state[8] = j8;
+	m_state[9] = j9;
+}
+
+NAMESPACE_END
-- 
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