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Java library for Javascript Object Signing and Encryption (JOSE) and
JSON Web Tokens (JWT)
/*
* nimbus-jose-jwt
*
* Copyright 2012-2016, 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;
import java.util.Arrays;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import com.nimbusds.jose.*;
import com.nimbusds.jose.crypto.impl.*;
import com.nimbusds.jose.jwk.OctetSequenceKey;
import com.nimbusds.jose.util.Base64URL;
import com.nimbusds.jose.util.ByteUtils;
import com.nimbusds.jose.util.Container;
import net.jcip.annotations.ThreadSafe;
/**
* AES and AES GCM key wrap encrypter of {@link com.nimbusds.jose.JWEObject JWE
* objects}. Expects an AES key.
*
* Encrypts the plain text with a generated AES key (the Content Encryption
* Key) according to the specified JOSE encryption method, then wraps the CEK
* with the specified AES key and returns it alongside the IV, cipher text and
* authentication tag. See RFC 7518, sections
* 4.4 and
* 4.7 for more
* information.
*
*
This class is thread-safe.
*
*
Supports the following key management algorithms:
*
*
* - {@link com.nimbusds.jose.JWEAlgorithm#A128KW}
*
- {@link com.nimbusds.jose.JWEAlgorithm#A192KW}
*
- {@link com.nimbusds.jose.JWEAlgorithm#A256KW}
*
- {@link com.nimbusds.jose.JWEAlgorithm#A128GCMKW}
*
- {@link com.nimbusds.jose.JWEAlgorithm#A192GCMKW}
*
- {@link com.nimbusds.jose.JWEAlgorithm#A256GCMKW}
*
*
* Supports the following content encryption algorithms:
*
*
* - {@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256}
*
- {@link com.nimbusds.jose.EncryptionMethod#A192CBC_HS384}
*
- {@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512}
*
- {@link com.nimbusds.jose.EncryptionMethod#A128GCM}
*
- {@link com.nimbusds.jose.EncryptionMethod#A192GCM}
*
- {@link com.nimbusds.jose.EncryptionMethod#A256GCM}
*
- {@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256_DEPRECATED}
*
- {@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512_DEPRECATED}
*
- {@link com.nimbusds.jose.EncryptionMethod#XC20P}
*
*
* @author Melisa Halsband
* @author Vladimir Dzhuvinov
* @author Dimitar A. Stoikov
* @author Egor Puzanov
* @version 2023-09-10
*/
@ThreadSafe
public class AESEncrypter extends AESCryptoProvider implements JWEEncrypter {
/**
* Algorithm family constants.
*/
private enum AlgFamily {
AESKW, AESGCMKW
}
/**
* Creates a new AES encrypter.
*
* @param kek The Key Encryption Key. Must be 128 bits
* (16 bytes), 192 bits (24 bytes) or
* 256 bits (32 bytes). Must not be
* {@code null}.
* @param contentEncryptionKey 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 KeyLengthException If the KEK length is invalid.
*/
public AESEncrypter(final SecretKey kek, final SecretKey contentEncryptionKey)
throws KeyLengthException {
super(kek, contentEncryptionKey);
}
/**
* Creates a new AES encrypter.
*
* @param kek The Key Encryption Key. Must be 128 bits (16 bytes), 192
* bits (24 bytes) or 256 bits (32 bytes). Must not be
* {@code null}.
*
* @throws KeyLengthException If the KEK length is invalid.
*/
public AESEncrypter(final SecretKey kek)
throws KeyLengthException {
this(kek, null);
}
/**
* Creates a new AES encrypter.
*
* @param keyBytes The Key Encryption Key, as a byte array. Must be 128
* bits (16 bytes), 192 bits (24 bytes) or 256 bits (32
* bytes). Must not be {@code null}.
*
* @throws KeyLengthException If the KEK length is invalid.
*/
public AESEncrypter(final byte[] keyBytes)
throws KeyLengthException {
this(new SecretKeySpec(keyBytes, "AES"));
}
/**
* Creates a new AES encrypter.
*
* @param octJWK The Key Encryption Key, as a JWK. Must be 128 bits (16
* bytes), 192 bits (24 bytes), 256 bits (32 bytes), 384
* bits (48 bytes) or 512 bits (64 bytes) long. Must not
* be {@code null}.
*
* @throws KeyLengthException If the KEK length is invalid.
*/
public AESEncrypter(final OctetSequenceKey octJWK)
throws KeyLengthException {
this(octJWK.toSecretKey("AES"));
}
/**
* Encrypts the specified clear 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 clearText The clear text to encrypt. Must not be {@code null}.
*
* @return The resulting JWE crypto parts.
*
* @throws JOSEException If the JWE algorithm or method is not
* supported or if encryption failed for some
* other internal reason.
*/
@Deprecated
public JWECryptoParts encrypt(final JWEHeader header, final byte[] clearText)
throws JOSEException {
return encrypt(header, clearText, AAD.compute(header));
}
@Override
public JWECryptoParts encrypt(final JWEHeader header, final byte[] clearText, final byte[] aad)
throws JOSEException {
final JWEAlgorithm alg = JWEHeaderValidation.getAlgorithmAndEnsureNotNull(header);
final EncryptionMethod enc = header.getEncryptionMethod();
// Check the AES key size and determine the algorithm family
final AlgFamily algFamily;
if (alg.equals(JWEAlgorithm.A128KW)) {
if(ByteUtils.safeBitLength(getKey().getEncoded()) != 128){
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 128 bits for A128KW encryption");
}
algFamily = AlgFamily.AESKW;
} else if (alg.equals(JWEAlgorithm.A192KW)) {
if(ByteUtils.safeBitLength(getKey().getEncoded()) != 192){
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 192 bits for A192KW encryption");
}
algFamily = AlgFamily.AESKW;
} else if (alg.equals(JWEAlgorithm.A256KW)) {
if (ByteUtils.safeBitLength(getKey().getEncoded()) != 256) {
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 256 bits for A256KW encryption");
}
algFamily = AlgFamily.AESKW;
} else if (alg.equals(JWEAlgorithm.A128GCMKW)) {
if(ByteUtils.safeBitLength(getKey().getEncoded()) != 128){
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 128 bits for A128GCMKW encryption");
}
algFamily = AlgFamily.AESGCMKW;
} else if (alg.equals(JWEAlgorithm.A192GCMKW)) {
if(ByteUtils.safeBitLength(getKey().getEncoded()) != 192){
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 192 bits for A192GCMKW encryption");
}
algFamily = AlgFamily.AESGCMKW;
} else if (alg.equals(JWEAlgorithm.A256GCMKW)) {
if(ByteUtils.safeBitLength(getKey().getEncoded()) != 256){
throw new KeyLengthException("The Key Encryption Key (KEK) length must be 256 bits for A256GCMKW encryption");
}
algFamily = AlgFamily.AESGCMKW;
} else {
throw new JOSEException(AlgorithmSupportMessage.unsupportedJWEAlgorithm(alg, SUPPORTED_ALGORITHMS));
}
final JWEHeader updatedHeader; // We need to work on the header
final Base64URL encryptedKey; // The second JWE part
final SecretKey cek = getCEK(enc); // Generate and encrypt the CEK according to the enc method
if(AlgFamily.AESKW.equals(algFamily)) {
encryptedKey = Base64URL.encode(AESKW.wrapCEK(cek, getKey(), getJCAContext().getKeyEncryptionProvider()));
updatedHeader = header; // simply copy ref
} else if(AlgFamily.AESGCMKW.equals(algFamily)) {
final Container keyIV = new Container<>(AESGCM.generateIV(getJCAContext().getSecureRandom()));
final AuthenticatedCipherText authCiphCEK = AESGCMKW.encryptCEK(cek, keyIV, getKey(), getJCAContext().getKeyEncryptionProvider());
encryptedKey = Base64URL.encode(authCiphCEK.getCipherText());
// Add iv and tag to the header
updatedHeader = new JWEHeader.Builder(header).
iv(Base64URL.encode(keyIV.get())).
authTag(Base64URL.encode(authCiphCEK.getAuthenticationTag())).
build();
} else {
// This should never happen
throw new JOSEException("Unexpected JWE algorithm: " + alg);
}
// for JWEObject we need update the AAD as well
final byte[] updatedAAD = Arrays.equals(AAD.compute(header), aad) ? AAD.compute(updatedHeader) : aad;
return ContentCryptoProvider.encrypt(updatedHeader, clearText, updatedAAD, cek, encryptedKey, getJCAContext());
}
}
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