Example usage for org.bouncycastle.math.ec ECMultiplier multiply

Introduction

In this page you can find the example usage for org.bouncycastle.math.ec ECMultiplier multiply.

Prototype

ECPoint multiply(ECPoint p, BigInteger k);

Source Link

Document

Multiplies the ECPoint p by k, i.e.

Usage

From source file:com.yahoo.athenz.auth.util.Crypto.java

License:Apache License

public static PublicKey extractPublicKey(PrivateKey privateKey) throws CryptoException {

    // we only support RSA and ECDSA private keys

    PublicKey publicKey = null;//  ww w. ja v  a2 s  . c o  m
    switch (privateKey.getAlgorithm()) {
    case RSA:
        try {
            KeyFactory kf = KeyFactory.getInstance(RSA, BC_PROVIDER);
            RSAPrivateCrtKey rsaCrtKey = (RSAPrivateCrtKey) privateKey;
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(rsaCrtKey.getModulus(),
                    rsaCrtKey.getPublicExponent());
            publicKey = kf.generatePublic(keySpec);
        } catch (NoSuchProviderException ex) {
            LOG.error("extractPublicKey: RSA - Caught NoSuchProviderException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        } catch (NoSuchAlgorithmException ex) {
            LOG.error("extractPublicKey: RSA - Caught NoSuchAlgorithmException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        } catch (InvalidKeySpecException ex) {
            LOG.error("extractPublicKey: RSA - Caught InvalidKeySpecException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        }
        break;

    case ECDSA:
        try {
            KeyFactory kf = KeyFactory.getInstance(ECDSA, BC_PROVIDER);
            BCECPrivateKey ecPrivKey = (BCECPrivateKey) privateKey;
            ECMultiplier ecMultiplier = new FixedPointCombMultiplier();
            ECParameterSpec ecParamSpec = (ECParameterSpec) ecPrivKey.getParameters();
            ECPoint ecPointQ = ecMultiplier.multiply(ecParamSpec.getG(), ecPrivKey.getD());
            ECPublicKeySpec keySpec = new ECPublicKeySpec(ecPointQ, ecParamSpec);
            publicKey = kf.generatePublic(keySpec);
        } catch (NoSuchProviderException ex) {
            LOG.error("extractPublicKey: ECDSA - Caught NoSuchProviderException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        } catch (NoSuchAlgorithmException ex) {
            LOG.error(
                    "extractPublicKey: ECDSA - Caught NoSuchAlgorithmException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        } catch (InvalidKeySpecException ex) {
            LOG.error("extractPublicKey: ECDSA - Caught InvalidKeySpecException exception: " + ex.getMessage());
            throw new CryptoException(ex);
        }
        break;

    default:
        String msg = "Unsupported Key Algorithm: " + privateKey.getAlgorithm();
        LOG.error("extractPublicKey: " + msg);
        throw new CryptoException(msg);
    }
    return publicKey;
}

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