diff options
Diffstat (limited to 'crypto/src/math/ec/multiplier/WTauNafMultiplier.cs')
| -rw-r--r-- | crypto/src/math/ec/multiplier/WTauNafMultiplier.cs | 207 |
1 files changed, 105 insertions, 102 deletions
diff --git a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs index f1a605770..c2f78da93 100644 --- a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs +++ b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs @@ -4,117 +4,120 @@ using Org.BouncyCastle.Math.EC.Abc; namespace Org.BouncyCastle.Math.EC.Multiplier { - /** - * Class implementing the WTNAF (Window - * <code>τ</code>-adic Non-Adjacent Form) algorithm. - */ - internal class WTauNafMultiplier - : ECMultiplier - { - /** - * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} - * by <code>k</code> using the reduced <code>τ</code>-adic NAF (RTNAF) - * method. - * @param p The F2mPoint to multiply. - * @param k The integer by which to multiply <code>k</code>. - * @return <code>p</code> multiplied by <code>k</code>. - */ - public ECPoint Multiply(ECPoint point, BigInteger k, PreCompInfo preCompInfo) - { - if (!(point is F2mPoint)) - throw new ArgumentException("Only F2mPoint can be used in WTauNafMultiplier"); + /** + * Class implementing the WTNAF (Window + * <code>τ</code>-adic Non-Adjacent Form) algorithm. + */ + public class WTauNafMultiplier + : ECMultiplier + { + /** + * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} + * by <code>k</code> using the reduced <code>τ</code>-adic NAF (RTNAF) + * method. + * @param p The F2mPoint to multiply. + * @param k The integer by which to multiply <code>k</code>. + * @return <code>p</code> multiplied by <code>k</code>. + */ + public virtual ECPoint Multiply(ECPoint point, BigInteger k) + { + if (!(point is F2mPoint)) + throw new ArgumentException("Only F2mPoint can be used in WTauNafMultiplier"); - F2mPoint p = (F2mPoint)point; + F2mPoint p = (F2mPoint)point; - F2mCurve curve = (F2mCurve) p.Curve; - int m = curve.M; - sbyte a = (sbyte) curve.A.ToBigInteger().IntValue; - sbyte mu = curve.GetMu(); - BigInteger[] s = curve.GetSi(); + F2mCurve curve = (F2mCurve) p.Curve; + int m = curve.M; + sbyte a = (sbyte) curve.A.ToBigInteger().IntValue; + sbyte mu = curve.GetMu(); + BigInteger[] s = curve.GetSi(); - ZTauElement rho = Tnaf.PartModReduction(k, m, a, s, mu, (sbyte)10); + ZTauElement rho = Tnaf.PartModReduction(k, m, a, s, mu, (sbyte)10); - return MultiplyWTnaf(p, rho, preCompInfo, a, mu); - } + return MultiplyWTnaf(p, rho, curve.GetPreCompInfo(p), a, mu); + } - /** - * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} - * by an element <code>λ</code> of <code><b>Z</b>[τ]</code> using - * the <code>τ</code>-adic NAF (TNAF) method. - * @param p The F2mPoint to multiply. - * @param lambda The element <code>λ</code> of - * <code><b>Z</b>[τ]</code> of which to compute the - * <code>[τ]</code>-adic NAF. - * @return <code>p</code> multiplied by <code>λ</code>. - */ - private F2mPoint MultiplyWTnaf(F2mPoint p, ZTauElement lambda, - PreCompInfo preCompInfo, sbyte a, sbyte mu) - { - ZTauElement[] alpha; - if (a == 0) - { - alpha = Tnaf.Alpha0; - } - else - { - // a == 1 - alpha = Tnaf.Alpha1; - } + /** + * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} + * by an element <code>λ</code> of <code><b>Z</b>[τ]</code> using + * the <code>τ</code>-adic NAF (TNAF) method. + * @param p The F2mPoint to multiply. + * @param lambda The element <code>λ</code> of + * <code><b>Z</b>[τ]</code> of which to compute the + * <code>[τ]</code>-adic NAF. + * @return <code>p</code> multiplied by <code>λ</code>. + */ + private F2mPoint MultiplyWTnaf(F2mPoint p, ZTauElement lambda, + PreCompInfo preCompInfo, sbyte a, sbyte mu) + { + ZTauElement[] alpha; + if (a == 0) + { + alpha = Tnaf.Alpha0; + } + else + { + // a == 1 + alpha = Tnaf.Alpha1; + } - BigInteger tw = Tnaf.GetTw(mu, Tnaf.Width); + BigInteger tw = Tnaf.GetTw(mu, Tnaf.Width); - sbyte[]u = Tnaf.TauAdicWNaf(mu, lambda, Tnaf.Width, - BigInteger.ValueOf(Tnaf.Pow2Width), tw, alpha); + sbyte[]u = Tnaf.TauAdicWNaf(mu, lambda, Tnaf.Width, + BigInteger.ValueOf(Tnaf.Pow2Width), tw, alpha); - return MultiplyFromWTnaf(p, u, preCompInfo); - } - - /** - * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} - * by an element <code>λ</code> of <code><b>Z</b>[τ]</code> - * using the window <code>τ</code>-adic NAF (TNAF) method, given the - * WTNAF of <code>λ</code>. - * @param p The F2mPoint to multiply. - * @param u The the WTNAF of <code>λ</code>.. - * @return <code>λ * p</code> - */ - private static F2mPoint MultiplyFromWTnaf(F2mPoint p, sbyte[] u, - PreCompInfo preCompInfo) - { - F2mCurve curve = (F2mCurve)p.Curve; - sbyte a = (sbyte) curve.A.ToBigInteger().IntValue; + return MultiplyFromWTnaf(p, u, preCompInfo); + } + + /** + * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint} + * by an element <code>λ</code> of <code><b>Z</b>[τ]</code> + * using the window <code>τ</code>-adic NAF (TNAF) method, given the + * WTNAF of <code>λ</code>. + * @param p The F2mPoint to multiply. + * @param u The the WTNAF of <code>λ</code>.. + * @return <code>λ * p</code> + */ + private static F2mPoint MultiplyFromWTnaf(F2mPoint p, sbyte[] u, + PreCompInfo preCompInfo) + { + F2mCurve curve = (F2mCurve)p.Curve; + sbyte a = (sbyte) curve.A.ToBigInteger().IntValue; - F2mPoint[] pu; - if ((preCompInfo == null) || !(preCompInfo is WTauNafPreCompInfo)) - { - pu = Tnaf.GetPreComp(p, a); - p.SetPreCompInfo(new WTauNafPreCompInfo(pu)); - } - else - { - pu = ((WTauNafPreCompInfo)preCompInfo).GetPreComp(); - } + F2mPoint[] pu; + if ((preCompInfo == null) || !(preCompInfo is WTauNafPreCompInfo)) + { + pu = Tnaf.GetPreComp(p, a); - // q = infinity - F2mPoint q = (F2mPoint) p.Curve.Infinity; - for (int i = u.Length - 1; i >= 0; i--) - { - q = Tnaf.Tau(q); - if (u[i] != 0) - { - if (u[i] > 0) - { - q = q.AddSimple(pu[u[i]]); - } - else - { - // u[i] < 0 - q = q.SubtractSimple(pu[-u[i]]); - } - } - } + WTauNafPreCompInfo pre = new WTauNafPreCompInfo(); + pre.PreComp = pu; + curve.SetPreCompInfo(p, pre); + } + else + { + pu = ((WTauNafPreCompInfo)preCompInfo).PreComp; + } - return q; - } - } + // q = infinity + F2mPoint q = (F2mPoint) p.Curve.Infinity; + for (int i = u.Length - 1; i >= 0; i--) + { + q = Tnaf.Tau(q); + if (u[i] != 0) + { + if (u[i] > 0) + { + q = q.AddSimple(pu[u[i]]); + } + else + { + // u[i] < 0 + q = q.SubtractSimple(pu[-u[i]]); + } + } + } + + return q; + } + } } |