Java tutorial
package org.bouncycastle.jcajce.provider.asymmetric.ec; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import org.bouncycastle.asn1.ASN1ObjectIdentifier; import org.bouncycastle.asn1.ASN1OctetString; import org.bouncycastle.asn1.ASN1Primitive; import org.bouncycastle.asn1.DERBitString; import org.bouncycastle.asn1.DERNull; import org.bouncycastle.asn1.ASN1ObjectIdentifier; import org.bouncycastle.asn1.DEROctetString; import org.bouncycastle.asn1.x509.AlgorithmIdentifier; import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo; import org.bouncycastle.asn1.x9.X962Parameters; import org.bouncycastle.asn1.x9.X9ECParameters; import org.bouncycastle.asn1.x9.X9ECPoint; import org.bouncycastle.asn1.x9.X9IntegerConverter; import org.bouncycastle.asn1.x9.X9ObjectIdentifiers; import org.bouncycastle.crypto.params.ECDomainParameters; import org.bouncycastle.crypto.params.ECPublicKeyParameters; import org.bouncycastle.jcajce.provider.asymmetric.util.ECUtil; import org.bouncycastle.jcajce.provider.asymmetric.util.KeyUtil; import org.bouncycastle.jcajce.provider.config.ProviderConfiguration; import org.bouncycastle.jce.interfaces.ECPointEncoder; 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.jce.spec.ECPublicKeySpec; import org.bouncycastle.math.ec.ECCurve; import org.bouncycastle.math.ec.ECPoint; import org.bouncycastle.util.Strings; import org.bouncycastle.jcajce.provider.asymmetric.util.ECUtil; public class BCECPublicKey implements ECPublicKey, ECPointEncoder { static final long serialVersionUID = 2422789860422731812L; private String algorithm = "EC"; private boolean withCompression; private transient ECPublicKeyParameters ecPublicKey; private transient ECParameterSpec ecSpec; private transient ProviderConfiguration configuration; public BCECPublicKey(String algorithm, BCECPublicKey key) { this.algorithm = algorithm; this.ecPublicKey = key.ecPublicKey; this.ecSpec = key.ecSpec; this.withCompression = key.withCompression; this.configuration = key.configuration; } public BCECPublicKey(String algorithm, ECPublicKeySpec spec, ProviderConfiguration configuration) { this.algorithm = algorithm; if (spec.getParams() != null) { this.ecSpec = spec.getParams(); this.ecPublicKey = new ECPublicKeyParameters( ecSpec.getCurve().createPoint(spec.getQ().getAffineXCoord().toBigInteger(), spec.getQ().getAffineYCoord().toBigInteger()), ECUtil.getDomainParameters(configuration, spec.getParams())); } else { this.ecSpec = null; org.bouncycastle.jce.spec.ECParameterSpec s = configuration.getEcImplicitlyCa(); this.ecPublicKey = new ECPublicKeyParameters( s.getCurve().createPoint(spec.getQ().getAffineXCoord().toBigInteger(), spec.getQ().getAffineYCoord().toBigInteger()), ECUtil.getDomainParameters(configuration, (ECParameterSpec) null)); } this.configuration = configuration; } public BCECPublicKey(String algorithm, ECPublicKeyParameters params, ECParameterSpec spec, ProviderConfiguration configuration) { ECDomainParameters dp = params.getParameters(); this.algorithm = algorithm; this.ecPublicKey = params; this.configuration = configuration; if (spec == null) { this.ecSpec = new ECParameterSpec(dp.getCurve(), dp.getG(), dp.getN(), dp.getH(), dp.getSeed()); } else { this.ecSpec = spec; } } public BCECPublicKey(String algorithm, ECPublicKeyParameters params, ProviderConfiguration configuration) { this.algorithm = algorithm; this.ecPublicKey = params; this.ecSpec = null; this.configuration = configuration; } BCECPublicKey(ECPublicKey key, ProviderConfiguration configuration) { this.ecPublicKey = new ECPublicKeyParameters(key.getQ(), ECUtil.getDomainParameters(configuration, key.getParameters())); this.algorithm = key.getAlgorithm(); this.ecSpec = key.getParameters(); this.configuration = configuration; } BCECPublicKey(String algorithm, ECPoint q, ECParameterSpec ecSpec, ProviderConfiguration configuration) { this.algorithm = algorithm; this.ecPublicKey = new ECPublicKeyParameters(q, ECUtil.getDomainParameters(configuration, ecSpec)); this.ecSpec = ecSpec; this.configuration = configuration; } BCECPublicKey(SubjectPublicKeyInfo info, ProviderConfiguration configuration) { this.configuration = configuration; populateFromPubKeyInfo(info); } BCECPublicKey(String algorithm, SubjectPublicKeyInfo info, ProviderConfiguration configuration) { this.configuration = configuration; populateFromPubKeyInfo(info); this.algorithm = algorithm; } private void populateFromPubKeyInfo(SubjectPublicKeyInfo info) { X962Parameters params = X962Parameters.getInstance(info.getAlgorithmId().getParameters()); ECCurve curve; if (params.isNamedCurve()) { ASN1ObjectIdentifier oid = ASN1ObjectIdentifier.getInstance(params.getParameters()); X9ECParameters ecP = ECUtil.getNamedCurveByOid(oid); ecSpec = new ECNamedCurveParameterSpec(ECUtil.getCurveName(oid), ecP.getCurve(), ecP.getG(), ecP.getN(), ecP.getH(), ecP.getSeed()); curve = ((ECParameterSpec) ecSpec).getCurve(); } else if (params.isImplicitlyCA()) { ecSpec = null; curve = BouncyCastleProvider.CONFIGURATION.getEcImplicitlyCa().getCurve(); } else { X9ECParameters ecP = X9ECParameters.getInstance(params.getParameters()); ecSpec = new ECParameterSpec(ecP.getCurve(), ecP.getG(), ecP.getN(), ecP.getH(), ecP.getSeed()); curve = ((ECParameterSpec) ecSpec).getCurve(); } DERBitString bits = info.getPublicKeyData(); byte[] data = bits.getBytes(); ASN1OctetString key = new DEROctetString(data); // // extra octet string - one of our old certs... // if (data[0] == 0x04 && data[1] == data.length - 2 && (data[2] == 0x02 || data[2] == 0x03)) { int qLength = new X9IntegerConverter().getByteLength(curve); if (qLength >= data.length - 3) { try { key = (ASN1OctetString) ASN1Primitive.fromByteArray(data); } catch (IOException ex) { throw new IllegalArgumentException("error recovering public key"); } } } X9ECPoint derQ = new X9ECPoint(curve, key); this.ecPublicKey = new ECPublicKeyParameters(derQ.getPoint(), ECUtil.getDomainParameters(configuration, params)); } public String getAlgorithm() { return algorithm; } public String getFormat() { return "X.509"; } public byte[] getEncoded() { AlgorithmIdentifier algId = new AlgorithmIdentifier(X9ObjectIdentifiers.id_ecPublicKey, ECUtils.getDomainParametersFromName(ecSpec, withCompression)); byte[] pubKeyOctets = ecPublicKey.getQ().getEncoded(withCompression); // stored curve is null if ImplicitlyCa return KeyUtil.getEncodedSubjectPublicKeyInfo(algId, pubKeyOctets); } public ECParameterSpec getParams() { return (ECParameterSpec) ecSpec; } public ECParameterSpec getParameters() { return (ECParameterSpec) ecSpec; } public org.bouncycastle.math.ec.ECPoint getQ() { org.bouncycastle.math.ec.ECPoint q = ecPublicKey.getQ(); if (ecSpec == null) { return q.getDetachedPoint(); } return ecPublicKey.getQ(); } ECPublicKeyParameters engineGetKeyParameters() { return ecPublicKey; } public String toString() { return ECUtil.publicKeyToString("EC", ecPublicKey.getQ(), engineGetSpec()); } public void setPointFormat(String style) { withCompression = !("UNCOMPRESSED".equalsIgnoreCase(style)); } ECParameterSpec engineGetSpec() { if (ecSpec != null) { return (ECParameterSpec) ecSpec; } return BouncyCastleProvider.CONFIGURATION.getEcImplicitlyCa(); } public boolean equals(Object o) { if (!(o instanceof BCECPublicKey)) { return false; } BCECPublicKey other = (BCECPublicKey) o; return ecPublicKey.getQ().equals(other.ecPublicKey.getQ()) && (engineGetSpec().equals(other.engineGetSpec())); } public int hashCode() { return ecPublicKey.getQ().hashCode() ^ engineGetSpec().hashCode(); } private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); byte[] enc = (byte[]) in.readObject(); populateFromPubKeyInfo(SubjectPublicKeyInfo.getInstance(ASN1Primitive.fromByteArray(enc))); this.configuration = BouncyCastleProvider.CONFIGURATION; } private void writeObject(ObjectOutputStream out) throws IOException { out.defaultWriteObject(); out.writeObject(this.getEncoded()); } }