ECDHCryptoProvider.java
/*
* nimbus-jose-jwt
*
* Copyright 2012-2019, Connect2id Ltd and contributors.
*
* 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.impl;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;
import javax.crypto.SecretKey;
import com.nimbusds.jose.*;
import com.nimbusds.jose.jwk.Curve;
import com.nimbusds.jose.util.Base64URL;
/**
* The base abstract class for Elliptic Curve Diffie-Hellman encrypters and
* decrypters of {@link com.nimbusds.jose.JWEObject JWE objects}.
*
* <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 curves:
*
* <ul>
* <li>{@link com.nimbusds.jose.jwk.Curve#P_256}
* <li>{@link com.nimbusds.jose.jwk.Curve#P_384}
* <li>{@link com.nimbusds.jose.jwk.Curve#P_521}
* <li>{@link com.nimbusds.jose.jwk.Curve#X25519}
* </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 Vladimir Dzhuvinov
* @author Fernando Gonz��lez Callejas
* @author Egor Puzanov
* @version 2023-09-10
*/
public abstract class ECDHCryptoProvider extends BaseJWEProvider {
/**
* The supported JWE algorithms by the ECDH crypto provider class.
*/
public static final Set<JWEAlgorithm> SUPPORTED_ALGORITHMS;
/**
* The supported encryption methods by the ECDH crypto provider class.
*/
public static final Set<EncryptionMethod> SUPPORTED_ENCRYPTION_METHODS = ContentCryptoProvider.SUPPORTED_ENCRYPTION_METHODS;
static {
Set<JWEAlgorithm> algs = new LinkedHashSet<>();
algs.add(JWEAlgorithm.ECDH_ES);
algs.add(JWEAlgorithm.ECDH_ES_A128KW);
algs.add(JWEAlgorithm.ECDH_ES_A192KW);
algs.add(JWEAlgorithm.ECDH_ES_A256KW);
SUPPORTED_ALGORITHMS = Collections.unmodifiableSet(algs);
}
/**
* The elliptic curve.
*/
private final Curve curve;
/**
* The Concatenation Key Derivation Function (KDF).
*/
private final ConcatKDF concatKDF;
/**
* Creates a new Elliptic Curve Diffie-Hellman encryption /decryption
* provider.
*
* @param curve The elliptic curve. Must be supported and not
* {@code null}.
* @param cek The content encryption key (CEK) to use. If specified
* its algorithm must be "AES" or "ChaCha20" and its length
* must match the expected for the JWE encryption method
* ("enc"). If {@code null} a CEK will be generated for
* each JWE.
*
* @throws JOSEException If the elliptic curve is not supported.
*/
protected ECDHCryptoProvider(final Curve curve, final SecretKey cek)
throws JOSEException {
super(SUPPORTED_ALGORITHMS, ContentCryptoProvider.SUPPORTED_ENCRYPTION_METHODS, cek);
Curve definedCurve = curve != null ? curve : new Curve("unknown");
if (! supportedEllipticCurves().contains(curve)) {
throw new JOSEException(AlgorithmSupportMessage.unsupportedEllipticCurve(
definedCurve, supportedEllipticCurves()));
}
this.curve = curve;
concatKDF = new ConcatKDF("SHA-256");
}
/**
* Returns the Concatenation Key Derivation Function (KDF).
*
* @return The concat KDF.
*/
protected ConcatKDF getConcatKDF() {
return concatKDF;
}
/**
* Returns the names of the supported elliptic curves. These correspond
* to the {@code crv} EC JWK parameter.
*
* @return The supported elliptic curves.
*/
public abstract Set<Curve> supportedEllipticCurves();
/**
* Returns the elliptic curve of the key (JWK designation).
*
* @return The elliptic curve.
*/
public Curve getCurve() {
return curve;
}
/**
* Encrypts the specified plaintext using the specified shared secret
* ("Z").
*/
protected JWECryptoParts encryptWithZ(final JWEHeader header, final SecretKey Z, final byte[] clearText, final byte[] aad)
throws JOSEException {
final JWEAlgorithm alg = JWEHeaderValidation.getAlgorithmAndEnsureNotNull(header);
final ECDH.AlgorithmMode algMode = ECDH.resolveAlgorithmMode(alg);
final EncryptionMethod enc = header.getEncryptionMethod();
// Derive shared key via concat KDF
getConcatKDF().getJCAContext().setProvider(getJCAContext().getMACProvider()); // update before concat
SecretKey sharedKey = ECDH.deriveSharedKey(header, Z, getConcatKDF());
final SecretKey cek;
final Base64URL encryptedKey; // The CEK encrypted (second JWE part)
if (algMode.equals(ECDH.AlgorithmMode.DIRECT)) {
if (isCEKProvided()) {
throw new JOSEException("The provided CEK is not supported");
}
cek = sharedKey;
encryptedKey = null;
} else if (algMode.equals(ECDH.AlgorithmMode.KW)) {
cek = getCEK(enc);
encryptedKey = Base64URL.encode(AESKW.wrapCEK(cek, sharedKey, getJCAContext().getKeyEncryptionProvider()));
} else {
throw new JOSEException("Unexpected JWE ECDH algorithm mode: " + algMode);
}
return ContentCryptoProvider.encrypt(header, clearText, aad, cek, encryptedKey, getJCAContext());
}
/**
* Decrypts the encrypted JWE parts using the specified shared secret
* ("Z").
*/
protected byte[] decryptWithZ(final JWEHeader header,
final byte[] aad,
final SecretKey Z,
final Base64URL encryptedKey,
final Base64URL iv,
final Base64URL cipherText,
final Base64URL authTag)
throws JOSEException {
final JWEAlgorithm alg = JWEHeaderValidation.getAlgorithmAndEnsureNotNull(header);
final ECDH.AlgorithmMode algMode = ECDH.resolveAlgorithmMode(alg);
// Derive shared key via concat KDF
getConcatKDF().getJCAContext().setProvider(getJCAContext().getMACProvider()); // update before concat
SecretKey sharedKey = ECDH.deriveSharedKey(header, Z, getConcatKDF());
final SecretKey cek;
if (algMode.equals(ECDH.AlgorithmMode.DIRECT)) {
cek = sharedKey;
} else if (algMode.equals(ECDH.AlgorithmMode.KW)) {
if (encryptedKey == null) {
throw new JOSEException("Missing JWE encrypted key");
}
cek = AESKW.unwrapCEK(sharedKey, encryptedKey.decode(), getJCAContext().getKeyEncryptionProvider());
} else {
throw new JOSEException("Unexpected JWE ECDH algorithm mode: " + algMode);
}
return ContentCryptoProvider.decrypt(header, aad, encryptedKey, iv, cipherText, authTag, cek, getJCAContext());
}
}