diff options
Diffstat (limited to 'src/cz/crcs/ectester/common/util/ECUtil.java')
| -rw-r--r-- | src/cz/crcs/ectester/common/util/ECUtil.java | 144 |
1 files changed, 115 insertions, 29 deletions
diff --git a/src/cz/crcs/ectester/common/util/ECUtil.java b/src/cz/crcs/ectester/common/util/ECUtil.java index 4736f23..a7aff10 100644 --- a/src/cz/crcs/ectester/common/util/ECUtil.java +++ b/src/cz/crcs/ectester/common/util/ECUtil.java @@ -20,12 +20,15 @@ import java.security.interfaces.ECKey; import java.security.interfaces.ECPrivateKey; import java.security.interfaces.ECPublicKey; import java.security.spec.*; +import java.util.LinkedList; +import java.util.List; import java.util.Random; /** * @author Jan Jancar johny@neuromancer.sk */ public class ECUtil { + private static Random rand = new Random(); public static byte[] toByteArray(BigInteger what, int bits) { byte[] raw = what.toByteArray(); @@ -195,7 +198,7 @@ public class ECUtil { } } - public static byte[] semiRandomKey(EC_Curve curve) { + private static byte[] hashCurve(EC_Curve curve) { int bytes = (curve.getBits() + 7) / 8; byte[] result = new byte[bytes]; SHA1Digest digest = new SHA1Digest(); @@ -210,10 +213,87 @@ public class ECUtil { written += toWrite; digest.update(dig, 0, dig.length); } + return result; + } + + public static EC_Params fullRandomKey(EC_Curve curve) { + int bytes = (curve.getBits() + 7) / 8; + byte[] result = new byte[bytes]; + rand.nextBytes(result); BigInteger priv = new BigInteger(1, result); BigInteger order = new BigInteger(1, curve.getParam(EC_Consts.PARAMETER_R)[0]); priv = priv.mod(order); - return toByteArray(priv, curve.getBits()); + return new EC_Params(EC_Consts.PARAMETER_S, new byte[][]{toByteArray(priv, curve.getBits())}); + } + + public static EC_Params fixedRandomKey(EC_Curve curve) { + byte[] hash = hashCurve(curve); + BigInteger priv = new BigInteger(1, hash); + BigInteger order = new BigInteger(1, curve.getParam(EC_Consts.PARAMETER_R)[0]); + priv = priv.mod(order); + return new EC_Params(EC_Consts.PARAMETER_S, new byte[][]{toByteArray(priv, curve.getBits())}); + } + + private static BigInteger computeRHS(BigInteger x, BigInteger a, BigInteger b, BigInteger p) { + BigInteger rhs = x.modPow(BigInteger.valueOf(3), p); + rhs = rhs.add(a.multiply(x)).mod(p); + rhs = rhs.add(b).mod(p); + return rhs; + } + + public static EC_Params fullRandomPoint(EC_Curve curve) { + EllipticCurve ecCurve = curve.toCurve(); + + BigInteger p; + if (ecCurve.getField() instanceof ECFieldFp) { + ECFieldFp fp = (ECFieldFp) ecCurve.getField(); + p = fp.getP(); + } else { + //TODO + return null; + } + BigInteger x; + BigInteger rhs; + do { + x = new BigInteger(ecCurve.getField().getFieldSize(), rand).mod(p); + rhs = computeRHS(x, ecCurve.getA(), ecCurve.getB(), p); + } while (!isResidue(rhs, p)); + BigInteger y = modSqrt(rhs, p); + if (rand.nextBoolean()) { + y = p.subtract(y); + } + + byte[] xArr = toByteArray(x, ecCurve.getField().getFieldSize()); + byte[] yArr = toByteArray(y, ecCurve.getField().getFieldSize()); + return new EC_Params(EC_Consts.PARAMETER_W, new byte[][]{xArr, yArr}); + } + + public static EC_Params fixedRandomPoint(EC_Curve curve) { + EllipticCurve ecCurve = curve.toCurve(); + + BigInteger p; + if (ecCurve.getField() instanceof ECFieldFp) { + ECFieldFp fp = (ECFieldFp) ecCurve.getField(); + p = fp.getP(); + } else { + //TODO + return null; + } + + BigInteger x = new BigInteger(1, hashCurve(curve)).mod(p); + BigInteger rhs = computeRHS(x, ecCurve.getA(), ecCurve.getB(), p); + while (!isResidue(rhs, p)) { + x = x.add(BigInteger.ONE).mod(p); + rhs = computeRHS(x, ecCurve.getA(), ecCurve.getB(), p); + } + BigInteger y = modSqrt(rhs, p); + if (y.bitCount() % 2 == 0) { + y = p.subtract(y); + } + + byte[] xArr = toByteArray(x, ecCurve.getField().getFieldSize()); + byte[] yArr = toByteArray(y, ecCurve.getField().getFieldSize()); + return new EC_Params(EC_Consts.PARAMETER_W, new byte[][]{xArr, yArr}); } public static ECPoint toPoint(EC_Params params) { @@ -294,6 +374,38 @@ public class ECUtil { } } + public static EC_Params joinParams(EC_Params... params) { + List<EC_Params> paramList = new LinkedList<>(); + short paramMask = 0; + int len = 0; + for (EC_Params param : params) { + if (param == null) { + continue; + } + int i = 0; + for (; i + 1 < paramList.size(); ++i) { + if (paramList.get(i + 1).getParams() == param.getParams()) { + throw new IllegalArgumentException(); + } + if (paramList.get(i + 1).getParams() < param.getParams()) { + break; + } + } + paramList.add(i, param); + paramMask |= param.getParams(); + len += param.numParams(); + } + + byte[][] res = new byte[len][]; + int i = 0; + for (EC_Params param : params) { + for (byte[] data : param.getData()) { + res[i++] = data.clone(); + } + } + return new EC_Params(paramMask, res); + } + public static EC_Params loadParams(short params, String named, String file) throws IOException { EC_Params result = null; if (file != null) { @@ -331,31 +443,5 @@ public class ECUtil { return null; } - public static EC_Params randomPoint(EllipticCurve curve) { - BigInteger x; - BigInteger p; - if (curve.getField() instanceof ECFieldFp) { - ECFieldFp fp = (ECFieldFp) curve.getField(); - p = fp.getP(); - } else { - //TODO - throw new UnsupportedOperationException(); - } - BigInteger rhs; - Random rand = new Random(); - do { - x = new BigInteger(curve.getField().getFieldSize(), rand); - x = x.mod(p); - rhs = x.modPow(BigInteger.valueOf(3), p); - rhs = rhs.add(curve.getA().multiply(x)).mod(p); - rhs = rhs.add(curve.getB()).mod(p); - } while (!isResidue(rhs, p)); - BigInteger y = modSqrt(rhs, p); - if (rand.nextBoolean()) { - y = p.subtract(y); - } - byte[] xArr = toByteArray(x, curve.getField().getFieldSize()); - byte[] yArr = toByteArray(y, curve.getField().getFieldSize()); - return new EC_Params(EC_Consts.PARAMETER_W, new byte[][]{xArr, yArr}); - } + } |