feat: Support for converting JWK to public key.

Author: peacekeeper

src/main/java/com/danubetech/keyformats/JWK_to_PublicKey.java

@@ -0,0 +1,107 @@
+package com.danubetech.keyformats;
+
+import bbs.signatures.KeyPair;
+import com.danubetech.keyformats.jose.Curve;
+import com.danubetech.keyformats.jose.JWK;
+import com.danubetech.keyformats.jose.KeyType;
+import com.danubetech.keyformats.jose.KeyTypeName;
+import com.danubetech.keyformats.keytypes.KeyTypeName_for_JWK;
+import org.bitcoinj.core.ECKey;
+
+import java.math.BigInteger;
+import java.security.KeyFactory;
+import java.security.interfaces.RSAPrivateKey;
+import java.security.interfaces.RSAPublicKey;
+import java.security.spec.RSAPrivateKeySpec;
+import java.security.spec.RSAPublicKeySpec;
+
+public class JWK_to_PublicKey {
+
+	public static Object JWK_to_anyPublicKey(JWK jsonWebKey) {
+
+		KeyTypeName keyType = KeyTypeName_for_JWK.keyTypeName_for_JWK(jsonWebKey);
+
+		if (keyType == KeyTypeName.RSA)
+			return JWK_to_RSAPublicKey(jsonWebKey);
+		else if (keyType == KeyTypeName.secp256k1)
+			return JWK_to_secp256k1PublicKey(jsonWebKey);
+		else if (keyType == KeyTypeName.BLS12381_G1)
+			return JWK_to_BLS12381_G2PublicKeyBytes(jsonWebKey);
+		else if (keyType == KeyTypeName.BLS12381_G2)
+			return JWK_to_BLS12381_G2PublicKeyBytes(jsonWebKey);
+		else if (keyType == KeyTypeName.Ed25519)
+			return JWK_to_Ed25519PublicKeyBytes(jsonWebKey);
+		else if (keyType == KeyTypeName.X25519)
+			return JWK_to_X25519PublicKeyBytes(jsonWebKey);
+		else
+			throw new IllegalArgumentException("Unsupported key type: " + keyType);
+	}
+
+	public static RSAPublicKey JWK_to_RSAPublicKey(JWK jsonWebKey) {
+
+		if (! KeyType.RSA.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+
+		try {
+			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
+			RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(new BigInteger(jsonWebKey.getNdecoded()), new BigInteger(jsonWebKey.getEdecoded()));
+			return (RSAPublicKey) keyFactory.generatePrivate(rsaPublicKeySpec);
+		} catch (Exception ex) {
+			throw new RuntimeException(ex.getMessage(), ex);
+		}
+	}
+
+	public static byte[] JWK_to_RSAPublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.RSA.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+
+		return JWK_to_RSAPublicKey(jsonWebKey).getEncoded();
+	}
+
+	public static ECKey JWK_to_secp256k1PublicKey(JWK jsonWebKey) {
+
+		if (! KeyType.EC.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.secp256k1.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return ECKey.fromPublicOnly(jsonWebKey.getXdecoded());
+	}
+
+	public static byte[] JWK_to_secp256k1PublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.EC.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.secp256k1.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return jsonWebKey.getXdecoded();
+	}
+
+	public static byte[] JWK_to_BLS12381_G1PublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.EC.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.BLS12381_G1.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return jsonWebKey.getXdecoded();
+	}
+
+	public static byte[] JWK_to_BLS12381_G2PublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.EC.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.BLS12381_G2.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return jsonWebKey.getXdecoded();
+	}
+
+	public static byte[] JWK_to_Ed25519PublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.OKP.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.Ed25519.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return jsonWebKey.getXdecoded();
+	}
+
+	public static byte[] JWK_to_X25519PublicKeyBytes(JWK jsonWebKey) {
+
+		if (! KeyType.OKP.equals(jsonWebKey.getKty())) throw new IllegalArgumentException("Incorrect key type: " + jsonWebKey.getKty());
+		if (! Curve.X25519.equals(jsonWebKey.getCrv())) throw new IllegalArgumentException("Incorrect curve: " + jsonWebKey.getCrv());
+
+		return jsonWebKey.getXdecoded();
+	}
+}