diff options
Diffstat (limited to 'rabin.cpp')
| -rw-r--r-- | rabin.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
@@ -5,6 +5,7 @@ #include "nbtheory.h" #include "asn.h" #include "sha.h" +#include "modarith.h" #include "oaep.cpp" @@ -138,11 +139,17 @@ void InvertibleRabinFunction::DEREncode(BufferedTransformation &bt) const seq.MessageEnd(); } -Integer InvertibleRabinFunction::CalculateInverse(const Integer &in) const +Integer InvertibleRabinFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &in) const { DoQuickSanityCheck(); - Integer cp=in%m_p, cq=in%m_q; + ModularArithmetic modn(m_n); + Integer r(rng, Integer::One(), m_n - Integer::One()); + r = modn.Square(r); + Integer r2 = modn.Square(r); + Integer c = modn.Multiply(in, r2); // blind + + Integer cp=c%m_p, cq=c%m_q; int jp = Jacobi(cp, m_p); int jq = Jacobi(cq, m_q); @@ -167,6 +174,8 @@ Integer InvertibleRabinFunction::CalculateInverse(const Integer &in) const Integer out = CRT(cq, m_q, cp, m_p, m_u); + out = modn.Divide(out, r); // unblind + if ((jq==-1 && out.IsEven()) || (jq==1 && out.IsOdd())) out = m_n-out; |