diff options
| -rw-r--r-- | crypto/src/math/ec/multiplier/WNafUtilities.cs | 36 |
1 files changed, 19 insertions, 17 deletions
diff --git a/crypto/src/math/ec/multiplier/WNafUtilities.cs b/crypto/src/math/ec/multiplier/WNafUtilities.cs index eac47222b..b6e32382f 100644 --- a/crypto/src/math/ec/multiplier/WNafUtilities.cs +++ b/crypto/src/math/ec/multiplier/WNafUtilities.cs @@ -307,26 +307,28 @@ namespace Org.BouncyCastle.Math.EC.Multiplier if (preCompLen < reqPreCompLen) { - ECPoint twiceP = wnafPreCompInfo.Twice; - if (twiceP == null) + preComp = ResizeTable(preComp, reqPreCompLen); + if (reqPreCompLen == 2) { - twiceP = preComp[0].Twice().Normalize(); - wnafPreCompInfo.Twice = twiceP; + preComp[1] = preComp[0].ThreeTimes(); } - - preComp = ResizeTable(preComp, reqPreCompLen); - - /* - * TODO Okeya/Sakurai paper has precomputation trick and "Montgomery's Trick" to speed this up. - * Also, co-Z arithmetic could avoid the subsequent normalization too. - */ - for (int i = preCompLen; i < reqPreCompLen; i++) + else { - /* - * Compute the new ECPoints for the precomputation array. The values 1, 3, 5, ..., - * 2^(width-1)-1 times p are computed - */ - preComp[i] = twiceP.Add(preComp[i - 1]); + ECPoint twiceP = wnafPreCompInfo.Twice; + if (twiceP == null) + { + twiceP = preComp[0].Twice().Normalize(); + wnafPreCompInfo.Twice = twiceP; + } + + for (int i = preCompLen; i < reqPreCompLen; i++) + { + /* + * Compute the new ECPoints for the precomputation array. The values 1, 3, 5, ..., + * 2^(width-1)-1 times p are computed + */ + preComp[i] = twiceP.Add(preComp[i - 1]); + } } /* |