org.id4me.Id4meKeyPairHandler Maven / Gradle / Ivy

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ID4me RelyingParty API prototype
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package org.id4me;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.UUID;

import org.json.JSONArray;
import org.json.JSONObject;

import com.nimbusds.jose.jwk.JWK;
import com.nimbusds.jose.jwk.KeyUse;
import com.nimbusds.jose.jwk.RSAKey;

/**
 * Simple class to handle public and private key to request encrypted token at
 * the client registration and decrypt the encrypted id token from the identity
 * authority . The keys could be created by the following commands: openssl
 * genrsa -out id4me.rsa.pem 4096 openssl rsa -pubout -in id4me.rsa.pem -out
 * id4me.pub.key.pem openssl pkcs8 -topk8 -inform PEM -outform PEM -in
 * id4me.rsa.pem -out id4me.priv.key.pem -nocrypt
 * 
 * The resulting id4me.priv.key.pem and id4me.pub.key.pem files should be used
 * to instantiate a Id4meKeyPairHandler
 * 
 * @author Peter Hoebel
 *
 */
class Id4meKeyPairHandler {
	private KeyPair keyPair = null;
	private String pub_key_file;
	private String priv_key_file;

	public Id4meKeyPairHandler(String pub_key_file, String priv_key_file) throws Exception {
		this.priv_key_file = priv_key_file;
		this.pub_key_file = pub_key_file;
		PublicKey pub_key = getPemPublicKey(pub_key_file);
		PrivateKey priv_key = getPemPrivateKey(priv_key_file);
		keyPair = new KeyPair(pub_key, priv_key);
	}

	public String toString() {
		return pub_key_file + ", " + priv_key_file;
	}

	public KeyPair getKeyPair() {
		return keyPair;
	}

	public JSONObject generateJwks() throws Exception {
		JWK jwk = generateJwk(keyPair);
		JSONObject jwks = new JSONObject();
		JSONArray keys = new JSONArray();
		JSONObject jwk_json = new JSONObject(jwk.toJSONString());
		jwk_json.remove("use");
		keys.put(jwk_json);
		jwks.put("keys", keys);
		return jwks;
	}

	private JWK generateJwk(KeyPair keyPair) throws Exception {
		// Convert to JWK format
		JWK jwk = new RSAKey.Builder((RSAPublicKey) keyPair.getPublic()).keyUse(KeyUse.SIGNATURE)
				.keyID(UUID.randomUUID().toString()).build();
		return jwk;

	}

	/**
	 * Create a {@link PrivateKey} from pem file.
	 * 
	 * @param path to the private key .pem file
	 * @return {@link java.security.PrivateKey}
	 * @throws Exception
	 */
	public PrivateKey getPemPrivateKey(String filename) throws Exception {
		String algorithm = "RSA";
		File f = new File(filename);
		FileInputStream fis = new FileInputStream(f);
		DataInputStream dis = new DataInputStream(fis);
		byte[] keyBytes = new byte[(int) f.length()];
		dis.readFully(keyBytes);
		dis.close();

		String temp = new String(keyBytes);
		String privKeyPEM = temp.replace("-----BEGIN PRIVATE KEY-----\n", "");
		privKeyPEM = privKeyPEM.replace("-----END PRIVATE KEY-----", "");
		byte[] decoded = Base64.getDecoder().decode(privKeyPEM);

		PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
		KeyFactory kf = KeyFactory.getInstance(algorithm);
		return kf.generatePrivate(spec);
	}

	/**
	 * Create a {@link PublicKey} from pem file.
	 * 
	 * @param path to the private key .pem file
	 * @return {@link java.security.PublicKey}
	 * @throws Exception
	 */
	public PublicKey getPemPublicKey(String filename) throws Exception {
		String algorithm = "RSA";
		File f = new File(filename);
		FileInputStream fis = new FileInputStream(f);
		DataInputStream dis = new DataInputStream(fis);
		byte[] keyBytes = new byte[(int) f.length()];
		dis.readFully(keyBytes);
		dis.close();

		String temp = new String(keyBytes);
		String publicKeyPEM = temp.replace("-----BEGIN PUBLIC KEY-----\n", "");
		publicKeyPEM = publicKeyPEM.replace("-----END PUBLIC KEY-----", "");

		byte[] decoded = Base64.getDecoder().decode(publicKeyPEM);

		X509EncodedKeySpec spec = new X509EncodedKeySpec(decoded);
		KeyFactory kf = KeyFactory.getInstance(algorithm);
		return kf.generatePublic(spec);
	}
}