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The PKI Connector RESTAPI is a library that helps developing new PKI Connectors for TrustedX

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package com.safelayer.rap.crypto;

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
import java.util.Random;


public class CryptoUtils {

	private static final String BOUNCY_CASTLE_PROVIDER_ID = "BC";

	private static final Random rnd = new SecureRandom();

	public static synchronized BigInteger generatePositiveRandom() {
		byte[] serialBytes = new byte[8];
		rnd.nextBytes(serialBytes);
		serialBytes[0] &= 0x7F;
		return new BigInteger(serialBytes);
	}

	public static void verify(PublicKey publicKey, SignatureAlgorithm signatureAlgorithm, byte[] data, byte[] signed) throws Exception {
		Signature signature = Signature.getInstance(signatureAlgorithm.getJavaAlgorithm(), BOUNCY_CASTLE_PROVIDER_ID);
		signature.initVerify(publicKey);
		signature.update(data);
		if (!signature.verify(signed))
			throw new InvalidSignatureException();

	}

	public static String getJavaAlgorithm(String signatureAlgorithmId) throws Exception {
		return SignatureAlgorithm.valueOfId(signatureAlgorithmId).getJavaAlgorithm();
	}

	public static AlgorithmIdentifier getBCAlgorithm(String signatureAlgorithmId) throws Exception {
		return SignatureAlgorithm.valueOfId(signatureAlgorithmId).getBcAlgorithm();
	}

	public static byte[] digest(byte[] data, String digestAlgorithmId) throws Exception {
		MessageDigest digest = MessageDigest.getInstance(digestAlgorithmId.toLowerCase(), BOUNCY_CASTLE_PROVIDER_ID);
		return digest.digest(data);
	}

	public static SignatureAlgorithm getSignatureAlgorithm(String signatureAlgorithmId, String digestAlgorithmId) throws InvalidAlgorithmException {
		final String signAlgoIdLowerCase = signatureAlgorithmId.toLowerCase();
		BaseSignatureAlgorithm signatureAlgorithm = BaseSignatureAlgorithm.unsafeValueOfId(signAlgoIdLowerCase);
		if (signatureAlgorithm == null)
			return SignatureAlgorithm.valueOfId(signAlgoIdLowerCase);

		DigestAlgorithm digestAlgorithm = DigestAlgorithm.valueOfId(digestAlgorithmId.toLowerCase());
		return SignatureAlgorithm.compose(signatureAlgorithm, digestAlgorithm);
	}

}