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added blinding and error checking for RW private key operation

import/raw
weidai 2007-04-15 22:58:24 +00:00
parent e9e7fbcfa6
commit e2aeed2e2d
1 changed files with 26 additions and 12 deletions
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38
trunk/c5/rw.cpp
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@ -121,26 +121,40 @@ void InvertibleRWFunction::DEREncode(BufferedTransformation &bt) const
seq.MessageEnd(); seq.MessageEnd();
} }
Integer InvertibleRWFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &in) const Integer InvertibleRWFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const
{ {
// no need to do blinding because RW is only used for signatures
DoQuickSanityCheck(); DoQuickSanityCheck();
ModularArithmetic modn(m_n);
Integer r, rInv;
do { // do this in a loop for people using small numbers for testing
r.Randomize(rng, Integer::One(), m_n - Integer::One());
rInv = modn.MultiplicativeInverse(r);
} while (rInv.IsZero());
Integer re = modn.Square(r);
re = modn.Multiply(re, x); // blind
Integer cp=in%m_p, cq=in%m_q; Integer cp=re%m_p, cq=re%m_q;
if (Jacobi(cp, m_p) * Jacobi(cq, m_q) != 1) if (Jacobi(cp, m_p) * Jacobi(cq, m_q) != 1)
{ {
cp = cp%2 ? (cp+m_p) >> 1 : cp >> 1; cp = cp.IsOdd() ? (cp+m_p) >> 1 : cp >> 1;
cq = cq%2 ? (cq+m_q) >> 1 : cq >> 1; cq = cq.IsOdd() ? (cq+m_q) >> 1 : cq >> 1;
} }
cp = ModularSquareRoot(cp, m_p); #pragma omp parallel
cq = ModularSquareRoot(cq, m_q); #pragma omp sections
{
#pragma omp section
cp = ModularSquareRoot(cp, m_p);
#pragma omp section
cq = ModularSquareRoot(cq, m_q);
}
Integer out = CRT(cq, m_q, cp, m_p, m_u); Integer y = CRT(cq, m_q, cp, m_p, m_u);
y = modn.Multiply(y, rInv); // unblind
return STDMIN(out, m_n-out); y = STDMIN(y, m_n-y);
if (ApplyFunction(y) != x) // check
throw Exception(Exception::OTHER_ERROR, "InvertibleRWFunction: computational error during private key operation");
return y;
} }
bool InvertibleRWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const bool InvertibleRWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const