diff options
Diffstat (limited to 'crypto/src/math/ec/multiplier/FpNafMultiplier.cs')
| -rw-r--r-- | crypto/src/math/ec/multiplier/FpNafMultiplier.cs | 66 |
1 files changed, 34 insertions, 32 deletions
diff --git a/crypto/src/math/ec/multiplier/FpNafMultiplier.cs b/crypto/src/math/ec/multiplier/FpNafMultiplier.cs index f5a98501a..3453e5600 100644 --- a/crypto/src/math/ec/multiplier/FpNafMultiplier.cs +++ b/crypto/src/math/ec/multiplier/FpNafMultiplier.cs @@ -1,39 +1,41 @@ namespace Org.BouncyCastle.Math.EC.Multiplier { - /** - * Class implementing the NAF (Non-Adjacent Form) multiplication algorithm. - */ - internal class FpNafMultiplier - : ECMultiplier - { - /** - * D.3.2 pg 101 - * @see org.bouncycastle.math.ec.multiplier.ECMultiplier#multiply(org.bouncycastle.math.ec.ECPoint, java.math.BigInteger) - */ - public ECPoint Multiply(ECPoint p, BigInteger k, PreCompInfo preCompInfo) - { - // TODO Probably should try to add this - // BigInteger e = k.Mod(n); // n == order of p - BigInteger e = k; - BigInteger h = e.Multiply(BigInteger.Three); + /** + * Class implementing the NAF (Non-Adjacent Form) multiplication algorithm. + */ + internal class FpNafMultiplier + : ECMultiplier + { + /** + * D.3.2 pg 101 + * @see org.bouncycastle.math.ec.multiplier.ECMultiplier#multiply(org.bouncycastle.math.ec.ECPoint, java.math.BigInteger) + */ + public ECPoint Multiply(ECPoint p, BigInteger k, PreCompInfo preCompInfo) + { + // TODO Probably should try to add this + // BigInteger e = k.Mod(n); // n == order of p + BigInteger e = k; + BigInteger h = e.Multiply(BigInteger.Three); - ECPoint neg = p.Negate(); - ECPoint R = p; + ECPoint neg = p.Negate(); + ECPoint R = p; - for (int i = h.BitLength - 2; i > 0; --i) - { - R = R.Twice(); + for (int i = h.BitLength - 2; i > 0; --i) + { + bool hBit = h.TestBit(i); + bool eBit = e.TestBit(i); - bool hBit = h.TestBit(i); - bool eBit = e.TestBit(i); + if (hBit == eBit) + { + R = R.Twice(); + } + else + { + R = R.TwicePlus(hBit ? p : neg); + } + } - if (hBit != eBit) - { - R = R.Add(hBit ? p : neg); - } - } - - return R; - } - } + return R; + } + } } |