Java tutorial
package org.bouncycastle.jcajce.provider.asymmetric.util; import java.lang.reflect.Method; import java.math.BigInteger; import java.security.AccessController; import java.security.InvalidKeyException; import java.security.PrivateKey; import java.security.PrivilegedAction; import java.security.PublicKey; import java.security.spec.AlgorithmParameterSpec; import java.util.Enumeration; import java.util.Map; import org.bouncycastle.asn1.ASN1ObjectIdentifier; import org.bouncycastle.asn1.pkcs.PrivateKeyInfo; import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo; import org.bouncycastle.asn1.x9.ECNamedCurveTable; import org.bouncycastle.asn1.x9.X962Parameters; import org.bouncycastle.asn1.x9.X9ECParameters; import org.bouncycastle.crypto.ec.CustomNamedCurves; import org.bouncycastle.crypto.params.AsymmetricKeyParameter; import org.bouncycastle.crypto.params.ECDomainParameters; import org.bouncycastle.crypto.params.ECNamedDomainParameters; import org.bouncycastle.crypto.params.ECPrivateKeyParameters; import org.bouncycastle.crypto.params.ECPublicKeyParameters; import org.bouncycastle.jcajce.provider.config.ProviderConfiguration; import org.bouncycastle.jce.interfaces.ECPrivateKey; import org.bouncycastle.jce.interfaces.ECPublicKey; import org.bouncycastle.jce.provider.BouncyCastleProvider; import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec; import org.bouncycastle.jce.spec.ECParameterSpec; import org.bouncycastle.math.ec.ECCurve; import org.bouncycastle.math.ec.ECPoint; import org.bouncycastle.math.ec.FixedPointCombMultiplier; import org.bouncycastle.util.Arrays; import org.bouncycastle.util.Fingerprint; import org.bouncycastle.util.Strings; /** * utility class for converting jce/jca ECDSA, ECDH, and ECDHC * objects into their org.bouncycastle.crypto counterparts. */ public class ECUtil { /** * Returns a sorted array of middle terms of the reduction polynomial. * @param k The unsorted array of middle terms of the reduction polynomial * of length 1 or 3. * @return the sorted array of middle terms of the reduction polynomial. * This array always has length 3. */ static int[] convertMidTerms(int[] k) { int[] res = new int[3]; if (k.length == 1) { res[0] = k[0]; } else { if (k.length != 3) { throw new IllegalArgumentException("Only Trinomials and pentanomials supported"); } if (k[0] < k[1] && k[0] < k[2]) { res[0] = k[0]; if (k[1] < k[2]) { res[1] = k[1]; res[2] = k[2]; } else { res[1] = k[2]; res[2] = k[1]; } } else if (k[1] < k[2]) { res[0] = k[1]; if (k[0] < k[2]) { res[1] = k[0]; res[2] = k[2]; } else { res[1] = k[2]; res[2] = k[0]; } } else { res[0] = k[2]; if (k[0] < k[1]) { res[1] = k[0]; res[2] = k[1]; } else { res[1] = k[1]; res[2] = k[0]; } } } return res; } public static ECDomainParameters getDomainParameters(ProviderConfiguration configuration, org.bouncycastle.jce.spec.ECParameterSpec params) { ECDomainParameters domainParameters; if (params instanceof ECNamedCurveParameterSpec) { ECNamedCurveParameterSpec nParams = (ECNamedCurveParameterSpec) params; ASN1ObjectIdentifier nameOid = ECUtil.getNamedCurveOid(nParams.getName()); domainParameters = new ECNamedDomainParameters(nameOid, nParams.getCurve(), nParams.getG(), nParams.getN(), nParams.getH(), nParams.getSeed()); } else if (params == null) { org.bouncycastle.jce.spec.ECParameterSpec iSpec = configuration.getEcImplicitlyCa(); domainParameters = new ECDomainParameters(iSpec.getCurve(), iSpec.getG(), iSpec.getN(), iSpec.getH(), iSpec.getSeed()); } else { domainParameters = new ECDomainParameters(params.getCurve(), params.getG(), params.getN(), params.getH(), params.getSeed()); } return domainParameters; } public static ECDomainParameters getDomainParameters(ProviderConfiguration configuration, X962Parameters params) { ECDomainParameters domainParameters; if (params.isNamedCurve()) { ASN1ObjectIdentifier oid = ASN1ObjectIdentifier.getInstance(params.getParameters()); X9ECParameters ecP = ECUtil.getNamedCurveByOid(oid); if (ecP == null) { Map extraCurves = configuration.getAdditionalECParameters(); ecP = (X9ECParameters) extraCurves.get(oid); } domainParameters = new ECNamedDomainParameters(oid, ecP.getCurve(), ecP.getG(), ecP.getN(), ecP.getH(), ecP.getSeed()); } else if (params.isImplicitlyCA()) { org.bouncycastle.jce.spec.ECParameterSpec iSpec = configuration.getEcImplicitlyCa(); domainParameters = new ECDomainParameters(iSpec.getCurve(), iSpec.getG(), iSpec.getN(), iSpec.getH(), iSpec.getSeed()); } else { X9ECParameters ecP = X9ECParameters.getInstance(params.getParameters()); domainParameters = new ECDomainParameters(ecP.getCurve(), ecP.getG(), ecP.getN(), ecP.getH(), ecP.getSeed()); } return domainParameters; } public static AsymmetricKeyParameter generatePublicKeyParameter(PublicKey key) throws InvalidKeyException { if (key instanceof ECPublicKey) { ECPublicKey k = (ECPublicKey) key; ECParameterSpec s = k.getParameters(); return new ECPublicKeyParameters(k.getQ(), new ECDomainParameters(s.getCurve(), s.getG(), s.getN(), s.getH(), s.getSeed())); } else if (key instanceof java.security.interfaces.ECPublicKey) { java.security.interfaces.ECPublicKey pubKey = (java.security.interfaces.ECPublicKey) key; ECParameterSpec s = EC5Util.convertSpec(pubKey.getParams()); return new ECPublicKeyParameters(EC5Util.convertPoint(pubKey.getParams(), pubKey.getW()), new ECDomainParameters(s.getCurve(), s.getG(), s.getN(), s.getH(), s.getSeed())); } else { // see if we can build a key from key.getEncoded() try { byte[] bytes = key.getEncoded(); if (bytes == null) { throw new InvalidKeyException("no encoding for EC public key"); } PublicKey publicKey = BouncyCastleProvider.getPublicKey(SubjectPublicKeyInfo.getInstance(bytes)); if (publicKey instanceof java.security.interfaces.ECPublicKey) { return ECUtil.generatePublicKeyParameter(publicKey); } } catch (Exception e) { throw new InvalidKeyException("cannot identify EC public key: " + e.toString()); } } throw new InvalidKeyException("cannot identify EC public key."); } public static AsymmetricKeyParameter generatePrivateKeyParameter(PrivateKey key) throws InvalidKeyException { if (key instanceof ECPrivateKey) { ECPrivateKey k = (ECPrivateKey) key; ECParameterSpec s = k.getParameters(); if (s == null) { s = BouncyCastleProvider.CONFIGURATION.getEcImplicitlyCa(); } if (k.getParameters() instanceof ECNamedCurveParameterSpec) { String name = ((ECNamedCurveParameterSpec) k.getParameters()).getName(); return new ECPrivateKeyParameters(k.getD(), new ECNamedDomainParameters( ECNamedCurveTable.getOID(name), s.getCurve(), s.getG(), s.getN(), s.getH(), s.getSeed())); } else { return new ECPrivateKeyParameters(k.getD(), new ECDomainParameters(s.getCurve(), s.getG(), s.getN(), s.getH(), s.getSeed())); } } else if (key instanceof java.security.interfaces.ECPrivateKey) { java.security.interfaces.ECPrivateKey privKey = (java.security.interfaces.ECPrivateKey) key; ECParameterSpec s = EC5Util.convertSpec(privKey.getParams()); return new ECPrivateKeyParameters(privKey.getS(), new ECDomainParameters(s.getCurve(), s.getG(), s.getN(), s.getH(), s.getSeed())); } else { // see if we can build a key from key.getEncoded() try { byte[] bytes = key.getEncoded(); if (bytes == null) { throw new InvalidKeyException("no encoding for EC private key"); } PrivateKey privateKey = BouncyCastleProvider.getPrivateKey(PrivateKeyInfo.getInstance(bytes)); if (privateKey instanceof java.security.interfaces.ECPrivateKey) { return ECUtil.generatePrivateKeyParameter(privateKey); } } catch (Exception e) { throw new InvalidKeyException("cannot identify EC private key: " + e.toString()); } } throw new InvalidKeyException("can't identify EC private key."); } public static int getOrderBitLength(ProviderConfiguration configuration, BigInteger order, BigInteger privateValue) { if (order == null) // implicitly CA { ECParameterSpec implicitCA = configuration.getEcImplicitlyCa(); if (implicitCA == null) { return privateValue.bitLength(); // a guess but better than an exception! } return implicitCA.getN().bitLength(); } else { return order.bitLength(); } } public static ASN1ObjectIdentifier getNamedCurveOid(String curveName) { String name = curveName; int spacePos = name.indexOf(' '); if (spacePos > 0) { name = name.substring(spacePos + 1); } try { if (name.charAt(0) >= '0' && name.charAt(0) <= '2') { return new ASN1ObjectIdentifier(name); } } catch (IllegalArgumentException ex) { } return ECNamedCurveTable.getOID(name); } public static ASN1ObjectIdentifier getNamedCurveOid(ECParameterSpec ecParameterSpec) { for (Enumeration names = ECNamedCurveTable.getNames(); names.hasMoreElements();) { String name = (String) names.nextElement(); X9ECParameters params = ECNamedCurveTable.getByName(name); if (params.getN().equals(ecParameterSpec.getN()) && params.getH().equals(ecParameterSpec.getH()) && params.getCurve().equals(ecParameterSpec.getCurve()) && params.getG().equals(ecParameterSpec.getG())) { return org.bouncycastle.asn1.x9.ECNamedCurveTable.getOID(name); } } return null; } public static X9ECParameters getNamedCurveByOid(ASN1ObjectIdentifier oid) { X9ECParameters params = CustomNamedCurves.getByOID(oid); if (params == null) { params = ECNamedCurveTable.getByOID(oid); } return params; } public static X9ECParameters getNamedCurveByName(String curveName) { X9ECParameters params = CustomNamedCurves.getByName(curveName); if (params == null) { params = ECNamedCurveTable.getByName(curveName); } return params; } public static String getCurveName(ASN1ObjectIdentifier oid) { return ECNamedCurveTable.getName(oid); } public static String privateKeyToString(String algorithm, BigInteger d, org.bouncycastle.jce.spec.ECParameterSpec spec) { StringBuffer buf = new StringBuffer(); String nl = Strings.lineSeparator(); org.bouncycastle.math.ec.ECPoint q = new FixedPointCombMultiplier().multiply(spec.getG(), d).normalize(); buf.append(algorithm); buf.append(" Private Key [").append(ECUtil.generateKeyFingerprint(q, spec)).append("]").append(nl); buf.append(" X: ").append(q.getAffineXCoord().toBigInteger().toString(16)).append(nl); buf.append(" Y: ").append(q.getAffineYCoord().toBigInteger().toString(16)).append(nl); return buf.toString(); } public static String publicKeyToString(String algorithm, org.bouncycastle.math.ec.ECPoint q, org.bouncycastle.jce.spec.ECParameterSpec spec) { StringBuffer buf = new StringBuffer(); String nl = Strings.lineSeparator(); buf.append(algorithm); buf.append(" Public Key [").append(ECUtil.generateKeyFingerprint(q, spec)).append("]").append(nl); buf.append(" X: ").append(q.getAffineXCoord().toBigInteger().toString(16)).append(nl); buf.append(" Y: ").append(q.getAffineYCoord().toBigInteger().toString(16)).append(nl); return buf.toString(); } public static String generateKeyFingerprint(ECPoint publicPoint, org.bouncycastle.jce.spec.ECParameterSpec spec) { ECCurve curve = spec.getCurve(); ECPoint g = spec.getG(); if (curve != null) { return new Fingerprint(Arrays.concatenate(publicPoint.getEncoded(false), curve.getA().getEncoded(), curve.getB().getEncoded(), g.getEncoded(false))).toString(); } return new Fingerprint(publicPoint.getEncoded(false)).toString(); } public static String getNameFrom(final AlgorithmParameterSpec paramSpec) { return (String) AccessController.doPrivileged(new PrivilegedAction() { public Object run() { try { Method m = paramSpec.getClass().getMethod("getName"); return m.invoke(paramSpec); } catch (Exception e) { // ignore - maybe log? } return null; } }); } }