X25519Decrypter.java
/*
* nimbus-jose-jwt
*
* Copyright 2012-2018, Connect2id Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use
* this file except in compliance with the License. You may obtain a copy of the
* License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed
* under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
* CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/
package com.nimbusds.jose.crypto;
import java.util.Collections;
import java.util.Set;
import javax.crypto.SecretKey;
import com.nimbusds.jose.*;
import com.nimbusds.jose.crypto.impl.AAD;
import com.nimbusds.jose.crypto.impl.CriticalHeaderParamsDeferral;
import com.nimbusds.jose.crypto.impl.ECDH;
import com.nimbusds.jose.crypto.impl.ECDHCryptoProvider;
import com.nimbusds.jose.jwk.Curve;
import com.nimbusds.jose.jwk.OctetKeyPair;
import com.nimbusds.jose.util.Base64URL;
/**
* Curve25519 Elliptic Curve Diffie-Hellman decrypter of
* {@link com.nimbusds.jose.JWEObject JWE objects}.
* Expects a private {@link OctetKeyPair} key with {@code "crv"} X25519.
*
* <p>See <a href="https://tools.ietf.org/html/rfc8037">RFC 8037</a>
* for more information.
*
* <p>See also {@link ECDHDecrypter} for ECDH on other curves.
*
* <p>This class is thread-safe.
*
* <p>Supports the following key management algorithms:
*
* <ul>
* <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A128KW}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A192KW}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A256KW}
* </ul>
*
* <p>Supports the following elliptic curve:
*
* <ul>
* <li>{@link com.nimbusds.jose.jwk.Curve#X25519} (Curve25519)
* </ul>
*
* <p>Supports the following content encryption algorithms:
*
* <ul>
* <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A192CBC_HS384}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A128GCM}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A192GCM}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A256GCM}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256_DEPRECATED}
* <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512_DEPRECATED}
* <li>{@link com.nimbusds.jose.EncryptionMethod#XC20P}
* </ul>
*
* @author Tim McLean
* @author Egor Puzanov
* @version 2023-03-26
*/
public class X25519Decrypter extends ECDHCryptoProvider implements JWEDecrypter, CriticalHeaderParamsAware {
/**
* The private key.
*/
private final OctetKeyPair privateKey;
/**
* The critical header policy.
*/
private final CriticalHeaderParamsDeferral critPolicy = new CriticalHeaderParamsDeferral();
/**
* Creates a new Curve25519 Elliptic Curve Diffie-Hellman decrypter.
*
* @param privateKey The private key. Must not be {@code null}.
*
* @throws JOSEException If the key subtype is not supported.
*/
public X25519Decrypter(final OctetKeyPair privateKey)
throws JOSEException {
this(privateKey, null);
}
/**
* Creates a new Curve25519 Elliptic Curve Diffie-Hellman decrypter.
*
* @param privateKey The private key. Must not be {@code null}.
* @param defCritHeaders The names of the critical header parameters
* that are deferred to the application for
* processing, empty set or {@code null} if none.
*
* @throws JOSEException If the key subtype is not supported.
*/
public X25519Decrypter(final OctetKeyPair privateKey, final Set<String> defCritHeaders)
throws JOSEException {
super(privateKey.getCurve(), null);
if (! Curve.X25519.equals(privateKey.getCurve())) {
throw new JOSEException("X25519Decrypter only supports OctetKeyPairs with crv=X25519");
}
if (! privateKey.isPrivate()) {
throw new JOSEException("The OctetKeyPair doesn't contain a private part");
}
this.privateKey = privateKey;
critPolicy.setDeferredCriticalHeaderParams(defCritHeaders);
}
@Override
public Set<Curve> supportedEllipticCurves() {
return Collections.singleton(Curve.X25519);
}
/**
* Returns the private key.
*
* @return The private key.
*/
public OctetKeyPair getPrivateKey() {
return privateKey;
}
@Override
public Set<String> getProcessedCriticalHeaderParams() {
return critPolicy.getProcessedCriticalHeaderParams();
}
@Override
public Set<String> getDeferredCriticalHeaderParams() {
return critPolicy.getProcessedCriticalHeaderParams();
}
/**
* Decrypts the specified cipher text of a {@link JWEObject JWE Object}.
*
* @param header The JSON Web Encryption (JWE) header. Must
* specify a supported JWE algorithm and method.
* Must not be {@code null}.
* @param encryptedKey The encrypted key, {@code null} if not required
* by the JWE algorithm.
* @param iv The initialisation vector, {@code null} if not
* required by the JWE algorithm.
* @param cipherText The cipher text to decrypt. Must not be
* {@code null}.
* @param authTag The authentication tag, {@code null} if not
* required.
*
* @return The clear text.
*
* @throws JOSEException If the JWE algorithm or method is not
* supported, if a critical header parameter is
* not supported or marked for deferral to the
* application, or if decryption failed for some
* other reason.
*/
@Deprecated
public byte[] decrypt(final JWEHeader header,
final Base64URL encryptedKey,
final Base64URL iv,
final Base64URL cipherText,
final Base64URL authTag)
throws JOSEException {
return decrypt(header, encryptedKey, iv, cipherText, authTag, AAD.compute(header));
}
@Override
public byte[] decrypt(final JWEHeader header,
final Base64URL encryptedKey,
final Base64URL iv,
final Base64URL cipherText,
final Base64URL authTag,
final byte[] aad)
throws JOSEException {
// Check for unrecognizable "crit" properties
critPolicy.ensureHeaderPasses(header);
// Get ephemeral key from header
OctetKeyPair ephemeralPublicKey = (OctetKeyPair) header.getEphemeralPublicKey();
if (ephemeralPublicKey == null) {
throw new JOSEException("Missing ephemeral public key epk JWE header parameter");
}
if (! privateKey.getCurve().equals(ephemeralPublicKey.getCurve())) {
throw new JOSEException("Curve of ephemeral public key does not match curve of private key");
}
// Derive 'Z'
// Note: X25519 does not require public key validation
// See https://cr.yp.to/ecdh.html#validate
SecretKey Z = ECDH.deriveSharedSecret(ephemeralPublicKey, privateKey);
return decryptWithZ(header, aad, Z, encryptedKey, iv, cipherText, authTag);
}
}