RSADecrypter.java
/*
* nimbus-jose-jwt
*
* Copyright 2012-2016, 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.security.PrivateKey;
import java.util.Set;
import javax.crypto.SecretKey;
import static com.nimbusds.jose.jwk.gen.RSAKeyGenerator.MIN_KEY_SIZE_BITS;
import net.jcip.annotations.ThreadSafe;
import com.nimbusds.jose.*;
import com.nimbusds.jose.crypto.impl.*;
import com.nimbusds.jose.jwk.RSAKey;
import com.nimbusds.jose.util.Base64URL;
/**
* RSA decrypter of {@link com.nimbusds.jose.JWEObject JWE objects}. Expects a
* private RSA key.
*
* <p>Decrypts the encrypted Content Encryption Key (CEK) with the private RSA
* key, and then uses the CEK along with the IV and authentication tag to
* decrypt the cipher text. See RFC 7518, sections
* <a href="https://tools.ietf.org/html/rfc7518#section-4.2">4.2</a> and
* <a href="https://tools.ietf.org/html/rfc7518#section-4.3">4.3</a> for more
* information.
*
* <p>This class is thread-safe.
*
* <p>Supports the following key management algorithms:
*
* <ul>
* <li>{@link com.nimbusds.jose.JWEAlgorithm#RSA_OAEP_256}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#RSA_OAEP_384}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#RSA_OAEP_512}
* <li>{@link com.nimbusds.jose.JWEAlgorithm#RSA_OAEP} (deprecated)
* <li>{@link com.nimbusds.jose.JWEAlgorithm#RSA1_5} (deprecated)
* </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 David Ortiz
* @author Vladimir Dzhuvinov
* @author Dimitar A. Stoikov
* @author Egor Puzanov
* @version 2023-09-10
*/
@ThreadSafe
public class RSADecrypter extends RSACryptoProvider implements JWEDecrypter, CriticalHeaderParamsAware {
/**
* The critical header policy.
*/
private final CriticalHeaderParamsDeferral critPolicy = new CriticalHeaderParamsDeferral();
/**
* The private RSA key.
*/
private final PrivateKey privateKey;
/**
* Stores a CEK decryption exception is one was encountered during the
* last {@link #decrypt} run.
*/
private Exception cekDecryptionException;
/**
* Creates a new RSA decrypter. This constructor can also accept a
* private RSA key located in a PKCS#11 store that doesn't expose the
* private key parameters (such as a smart card or HSM).
*
* @param privateKey The private RSA key. Its algorithm must be "RSA"
* and its length at least 2048 bits. Note that the
* length of an RSA key in a PKCS#11 store cannot be
* checked. Must not be {@code null}.
*/
public RSADecrypter(final PrivateKey privateKey) {
this(privateKey, null, false);
}
/**
* Creates a new RSA decrypter.
*
* @param rsaJWK The RSA JSON Web Key (JWK). Must contain or reference
* a private part. Its length must be at least 2048 bits.
* Note that the length of an RSA key in a PKCS#11 store
* cannot be checked. Must not be {@code null}.
*
* @throws JOSEException If the RSA JWK doesn't contain a private part
* or its extraction failed.
*/
public RSADecrypter(final RSAKey rsaJWK)
throws JOSEException {
this(RSAKeyUtils.toRSAPrivateKey(rsaJWK));
}
/**
* Creates a new RSA decrypter. This constructor can also accept a
* private RSA key located in a PKCS#11 store that doesn't expose the
* private key parameters (such as a smart card or HSM).
*
* @param privateKey The private RSA key. Its algorithm must be
* "RSA" and its length at least 2048 bits. Note
* that the length of an RSA key in a PKCS#11
* store cannot be checked. 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.
*/
public RSADecrypter(final PrivateKey privateKey,
final Set<String> defCritHeaders) {
this(privateKey, defCritHeaders, false);
}
/**
* Creates a new RSA decrypter. This constructor can also accept a
* private RSA key located in a PKCS#11 store that doesn't expose the
* private key parameters (such as a smart card or HSM).
*
* @param privateKey The private RSA key. Its algorithm must be
* "RSA" and its length at least 2048 bits. Note
* that the length of an RSA key in a PKCS#11
* store cannot be checked. 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.
* @param allowWeakKey {@code true} to allow an RSA key shorter than
* 2048 bits.
*/
public RSADecrypter(final PrivateKey privateKey,
final Set<String> defCritHeaders,
final boolean allowWeakKey) {
super(null);
if (! privateKey.getAlgorithm().equalsIgnoreCase("RSA")) {
throw new IllegalArgumentException("The private key algorithm must be RSA");
}
if (! allowWeakKey) {
int keyBitLength = RSAKeyUtils.keyBitLength(privateKey);
if (keyBitLength > 0 && keyBitLength < MIN_KEY_SIZE_BITS) {
throw new IllegalArgumentException("The RSA key size must be at least " + MIN_KEY_SIZE_BITS + " bits");
}
}
this.privateKey = privateKey;
critPolicy.setDeferredCriticalHeaderParams(defCritHeaders);
}
/**
* Gets the private RSA key.
*
* @return The private RSA key. Casting to
* {@link java.security.interfaces.RSAPrivateKey} may not be
* possible if the key is located in a PKCS#11 store that
* doesn't expose the private key parameters.
*/
public PrivateKey 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 {
// Validate required JWE parts
if (encryptedKey == null) {
throw new JOSEException("Missing JWE encrypted key");
}
if (iv == null) {
throw new JOSEException("Missing JWE initialization vector (IV)");
}
if (authTag == null) {
throw new JOSEException("Missing JWE authentication tag");
}
critPolicy.ensureHeaderPasses(header);
// Derive the content encryption key
JWEAlgorithm alg = JWEHeaderValidation.getAlgorithmAndEnsureNotNull(header);
SecretKey cek;
if (alg.equals(JWEAlgorithm.RSA1_5)) {
int keyLength = header.getEncryptionMethod().cekBitLength();
// Protect against MMA attack by generating random CEK to be used on decryption failure,
// see http://www.ietf.org/mail-archive/web/jose/current/msg01832.html
final SecretKey randomCEK = ContentCryptoProvider.generateCEK(header.getEncryptionMethod(), getJCAContext().getSecureRandom());
try {
cek = RSA1_5.decryptCEK(privateKey, encryptedKey.decode(), keyLength, getJCAContext().getKeyEncryptionProvider());
if (cek == null) {
// CEK length mismatch, signalled by null instead of
// exception to prevent MMA attack
cek = randomCEK;
}
} catch (Exception e) {
// continue
cekDecryptionException = e;
cek = randomCEK;
}
cekDecryptionException = null;
} else if (alg.equals(JWEAlgorithm.RSA_OAEP)) {
cek = RSA_OAEP.decryptCEK(privateKey, encryptedKey.decode(), getJCAContext().getKeyEncryptionProvider());
} else if (alg.equals(JWEAlgorithm.RSA_OAEP_256)) {
cek = RSA_OAEP_SHA2.decryptCEK(privateKey, encryptedKey.decode(), 256, getJCAContext().getKeyEncryptionProvider());
} else if (alg.equals(JWEAlgorithm.RSA_OAEP_384)) {
cek = RSA_OAEP_SHA2.decryptCEK(privateKey, encryptedKey.decode(), 384, getJCAContext().getKeyEncryptionProvider());
} else if (alg.equals(JWEAlgorithm.RSA_OAEP_512)){
cek = RSA_OAEP_SHA2.decryptCEK(privateKey, encryptedKey.decode(), 512, getJCAContext().getKeyEncryptionProvider());
} else {
throw new JOSEException(AlgorithmSupportMessage.unsupportedJWEAlgorithm(alg, SUPPORTED_ALGORITHMS));
}
return ContentCryptoProvider.decrypt(header, aad, encryptedKey, iv, cipherText, authTag, cek, getJCAContext());
}
/**
* Returns the Content Encryption Key (CEK) decryption exception if one
* was encountered during the last {@link #decrypt} run. Intended for
* logging and debugging purposes.
*
* @return The recorded exception, {@code null} if none.
*/
public Exception getCEKDecryptionException() {
return cekDecryptionException;
}
}