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Fix for CVE-2015-2141. Thanks to Evgeny Sidorov for reporting. Squaring to satisfy Jacobi requirements suggested by JPM.

pull/2/head
Jeffrey Walton 2015-06-27 17:56:01 -04:00
parent cf08f3e98d
commit 9425e16437
1 changed files with 7 additions and 1 deletions
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8
rw.cpp
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@ -126,10 +126,16 @@ Integer InvertibleRWFunction::CalculateInverse(RandomNumberGenerator &rng, const
DoQuickSanityCheck(); DoQuickSanityCheck();
ModularArithmetic modn(m_n); ModularArithmetic modn(m_n);
Integer r, rInv; Integer r, rInv;
do { // do this in a loop for people using small numbers for testing
// do this in a loop for people using small numbers for testing
do {
r.Randomize(rng, Integer::One(), m_n - Integer::One()); r.Randomize(rng, Integer::One(), m_n - Integer::One());
// Fix for CVE-2015-2141. Thanks to Evgeny Sidorov for reporting.
// Squaring to satisfy Jacobi requirements suggested by JPM.
r = modn.Square(r);
rInv = modn.MultiplicativeInverse(r); rInv = modn.MultiplicativeInverse(r);
} while (rInv.IsZero()); } while (rInv.IsZero());
Integer re = modn.Square(r); Integer re = modn.Square(r);
re = modn.Multiply(re, x); // blind re = modn.Multiply(re, x); // blind