seal.cpp
// seal.cpp - written and placed in the public domain by Wei Dai
// updated to SEAL 3.0 by Leonard Janke
#include "pch.h"
#include "seal.h"
#include "sha.h"
#include "misc.h"
#include "secblock.h"
NAMESPACE_BEGIN(CryptoPP)
#if !defined(NDEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
void SEAL_TestInstantiations()
{
SEAL<>::Encryption x;
}
#endif
struct SEAL_Gamma
{
SEAL_Gamma(const byte *key)
: H(5), Z(5), D(16), lastIndex(0xffffffff)
{
GetUserKey(BIG_ENDIAN_ORDER, H.begin(), 5, key, 20);
memset(D, 0, 64);
}
word32 Apply(word32 i);
SecBlock<word32> H, Z, D;
word32 lastIndex;
};
word32 SEAL_Gamma::Apply(word32 i)
{
word32 shaIndex = i/5;
if (shaIndex != lastIndex)
{
memcpy(Z, H, 20);
D[0] = shaIndex;
SHA::Transform(Z, D);
lastIndex = shaIndex;
}
return Z[i%5];
}
template <class B>
void SEAL_Policy<B>::CipherSetKey(const NameValuePairs &params, const byte *key, size_t length)
{
CRYPTOPP_UNUSED(length);
m_insideCounter = m_outsideCounter = m_startCount = 0;
unsigned int L = params.GetIntValueWithDefault("NumberOfOutputBitsPerPositionIndex", 32*1024);
m_iterationsPerCount = L / 8192;
SEAL_Gamma gamma(key);
unsigned int i;
for (i=0; i<512; i++)
m_T[i] = gamma.Apply(i);
for (i=0; i<256; i++)
m_S[i] = gamma.Apply(0x1000+i);
m_R.New(4*(L/8192));
for (i=0; i<m_R.size(); i++)
m_R[i] = gamma.Apply(0x2000+i);
}
template <class B>
void SEAL_Policy<B>::CipherResynchronize(byte *keystreamBuffer, const byte *IV, size_t length)
{
CRYPTOPP_UNUSED(keystreamBuffer), CRYPTOPP_UNUSED(IV), CRYPTOPP_UNUSED(length);
assert(length==4);
m_outsideCounter = IV ? GetWord<word32>(false, BIG_ENDIAN_ORDER, IV) : 0;
m_startCount = m_outsideCounter;
m_insideCounter = 0;
}
template <class B>
void SEAL_Policy<B>::SeekToIteration(lword iterationCount)
{
m_outsideCounter = m_startCount + (unsigned int)(iterationCount / m_iterationsPerCount);
m_insideCounter = (unsigned int)(iterationCount % m_iterationsPerCount);
}
template <class B>
void SEAL_Policy<B>::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
word32 a, b, c, d, n1, n2, n3, n4;
unsigned int p, q;
assert(IsAlignedOn(m_T.begin(),GetAlignmentOf<word32>()));
for (size_t iteration = 0; iteration < iterationCount; ++iteration)
{
#define Ttab(x) *(word32 *)(void*)((byte *)m_T.begin()+x)
a = m_outsideCounter ^ m_R[4*m_insideCounter];
b = rotrFixed(m_outsideCounter, 8U) ^ m_R[4*m_insideCounter+1];
c = rotrFixed(m_outsideCounter, 16U) ^ m_R[4*m_insideCounter+2];
d = rotrFixed(m_outsideCounter, 24U) ^ m_R[4*m_insideCounter+3];
for (unsigned int j=0; j<2; j++)
{
p = a & 0x7fc;
b += Ttab(p);
a = rotrFixed(a, 9U);
p = b & 0x7fc;
c += Ttab(p);
b = rotrFixed(b, 9U);
p = c & 0x7fc;
d += Ttab(p);
c = rotrFixed(c, 9U);
p = d & 0x7fc;
a += Ttab(p);
d = rotrFixed(d, 9U);
}
n1 = d, n2 = b, n3 = a, n4 = c;
p = a & 0x7fc;
b += Ttab(p);
a = rotrFixed(a, 9U);
p = b & 0x7fc;
c += Ttab(p);
b = rotrFixed(b, 9U);
p = c & 0x7fc;
d += Ttab(p);
c = rotrFixed(c, 9U);
p = d & 0x7fc;
a += Ttab(p);
d = rotrFixed(d, 9U);
// generate 8192 bits
for (unsigned int i=0; i<64; i++)
{
p = a & 0x7fc;
a = rotrFixed(a, 9U);
b += Ttab(p);
b ^= a;
q = b & 0x7fc;
b = rotrFixed(b, 9U);
c ^= Ttab(q);
c += b;
p = (p+c) & 0x7fc;
c = rotrFixed(c, 9U);
d += Ttab(p);
d ^= c;
q = (q+d) & 0x7fc;
d = rotrFixed(d, 9U);
a ^= Ttab(q);
a += d;
p = (p+a) & 0x7fc;
b ^= Ttab(p);
a = rotrFixed(a, 9U);
q = (q+b) & 0x7fc;
c += Ttab(q);
b = rotrFixed(b, 9U);
p = (p+c) & 0x7fc;
d ^= Ttab(p);
c = rotrFixed(c, 9U);
q = (q+d) & 0x7fc;
d = rotrFixed(d, 9U);
a += Ttab(q);
#define SEAL_OUTPUT(x) \
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, B::ToEnum(), 0, b + m_S[4*i+0]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, B::ToEnum(), 1, c ^ m_S[4*i+1]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, B::ToEnum(), 2, d + m_S[4*i+2]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, B::ToEnum(), 3, a ^ m_S[4*i+3]);
CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH(SEAL_OUTPUT, 4*4);
if (i & 1)
{
a += n3;
b += n4;
c ^= n3;
d ^= n4;
}
else
{
a += n1;
b += n2;
c ^= n1;
d ^= n2;
}
}
if (++m_insideCounter == m_iterationsPerCount)
{
++m_outsideCounter;
m_insideCounter = 0;
}
}
a = b = c = d = n1 = n2 = n3 = n4 = 0;
p = q = 0;
}
template class SEAL_Policy<BigEndian>;
template class SEAL_Policy<LittleEndian>;
NAMESPACE_END
seal.h
Classes for SEAL stream cipher.
SecBlock::begin
iterator begin()
Provides an iterator pointing to the first element in the memory block.
Definition: secblock.h:499
IsAlignedOn
bool IsAlignedOn(const void *ptr, unsigned int alignment)
Determines whether ptr is aligned to a minimum value.
Definition: misc.h:907
BIG_ENDIAN_ORDER
@ BIG_ENDIAN_ORDER
byte order is big-endian
Definition: cryptlib.h:127
NameValuePairs::GetIntValueWithDefault
int GetIntValueWithDefault(const char *name, int defaultValue) const
Get a named value with type int, with default.
Definition: cryptlib.h:380
SymmetricCipherFinal
SymmetricCipher implementation.
Definition: strciphr.h:582
secblock.h
Classes and functions for secure memory allocations.
rotrFixed
T rotrFixed(T x, unsigned int y)
Performs a right rotate.
Definition: misc.h:1327
CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH
#define CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH(x, y)
Helper macro to implement OperateKeystream.
Definition: strciphr.h:237
misc.h
Utility functions for the Crypto++ library.
sha.h
Classes for SHA-1 and SHA-2 family of message digests.
KeystreamOperation
KeystreamOperation
Keystream operation flags.
Definition: strciphr.h:92
CryptoPP
Crypto++ library namespace.
SEAL_Policy
SEAL stream cipher operation.
Definition: seal.h:27
SecBlock< word32 >
NameValuePairs
Interface for retrieving values given their names.
Definition: cryptlib.h:277
SEAL_Gamma
Definition: seal.cpp:20