KeyProvider.java

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package dev.rafex.ether.jwt;
 
/*-
 * #%L
 * ether-jwt
 * %%
 * Copyright (C) 2025 - 2026 Raúl Eduardo González Argote
 * %%
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * #L%
 */
 
import java.nio.charset.StandardCharsets;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Arrays;
import java.util.Objects;
 
/** Provides cryptographic material used to sign and verify JWT tokens. */
public interface KeyProvider {
 
    JwtAlgorithm algorithm();
 
    byte[] hmacSecret();
 
    PrivateKey privateKey();
 
    PublicKey publicKey();
 
    static KeyProvider hmac(final String secret) {
        if (secret == null || secret.isBlank()) {
            throw new IllegalArgumentException("secret is required for HS256");
        }
        return hmac(secret.getBytes(StandardCharsets.UTF_8));
    }
 
    static KeyProvider hmac(final byte[] secret) {
        if (secret == null || secret.length == 0) {
            throw new IllegalArgumentException("secret is required for HS256");
        }
        final byte[] copy = Arrays.copyOf(secret, secret.length);
        return new BasicKeyProvider(JwtAlgorithm.HS256, copy, null, null);
    }
 
    static KeyProvider rsa(final PrivateKey privateKey, final PublicKey publicKey) {
        if (privateKey == null || publicKey == null) {
            throw new IllegalArgumentException("privateKey and publicKey are required for RS256");
        }
        return new BasicKeyProvider(JwtAlgorithm.RS256, null, privateKey, publicKey);
    }
 
    static KeyProvider rsaVerifier(final PublicKey publicKey) {
        if (publicKey == null) {
            throw new IllegalArgumentException("publicKey is required for RS256 verification");
        }
        return new BasicKeyProvider(JwtAlgorithm.RS256, null, null, publicKey);
    }
 
    final class BasicKeyProvider implements KeyProvider {
        private final JwtAlgorithm algorithm;
        private final byte[] hmacSecret;
        private final PrivateKey privateKey;
        private final PublicKey publicKey;
 
        private BasicKeyProvider(
                final JwtAlgorithm algorithm,
                final byte[] hmacSecret,
                final PrivateKey privateKey,
                final PublicKey publicKey) {
            this.algorithm = Objects.requireNonNull(algorithm, "algorithm");
            this.hmacSecret = hmacSecret == null ? null : Arrays.copyOf(hmacSecret, hmacSecret.length);
            this.privateKey = privateKey;
            this.publicKey = publicKey;
        }
 
        @Override
        public JwtAlgorithm algorithm() {
            return algorithm;
        }
 
        @Override
        public byte[] hmacSecret() {
            return hmacSecret == null ? null : Arrays.copyOf(hmacSecret, hmacSecret.length);
        }
 
        @Override
        public PrivateKey privateKey() {
            return privateKey;
        }
 
        @Override
        public PublicKey publicKey() {
            return publicKey;
        }
    }
}