/*
* Copyright 2013-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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.amazonaws.services.s3.internal.crypto;
import static com.amazonaws.services.s3.internal.crypto.KMSSecuredCEK.isKMSKeyWrapped;
import static com.amazonaws.services.s3.model.ExtraMaterialsDescription.NONE;
import static com.amazonaws.util.BinaryUtils.copyAllBytesFrom;
import com.amazonaws.services.kms.AWSKMS;
import com.amazonaws.util.StringUtils;
import static com.amazonaws.util.Throwables.failure;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;
import java.security.Key;
import java.security.Provider;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import com.amazonaws.SdkClientException;
import com.amazonaws.AmazonWebServiceRequest;
import com.amazonaws.services.kms.model.DecryptRequest;
import com.amazonaws.services.kms.model.DecryptResult;
import com.amazonaws.services.kms.model.EncryptRequest;
import com.amazonaws.services.kms.model.EncryptResult;
import com.amazonaws.services.s3.Headers;
import com.amazonaws.services.s3.KeyWrapException;
import com.amazonaws.services.s3.model.CryptoMode;
import com.amazonaws.services.s3.model.EncryptionMaterials;
import com.amazonaws.services.s3.model.EncryptionMaterialsAccessor;
import com.amazonaws.services.s3.model.ExtraMaterialsDescription;
import com.amazonaws.services.s3.model.KMSEncryptionMaterials;
import com.amazonaws.services.s3.model.MaterialsDescriptionProvider;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.util.Base64;
import com.amazonaws.util.json.Jackson;
/**
* Cryptographic material used for client-side content encrypt/decryption in S3.
* This includes the randomly generated one-time secured CEK
* (content-encryption-key) and the respective key wrapping algorithm, if any,
* and the cryptographic scheme in use.
*/
final class ContentCryptoMaterial {
// null if cek is not secured via key wrapping
private final String keyWrappingAlgorithm;
private final CipherLite cipherLite;
private final Map<String, String> kekMaterialsDescription;
private final byte[] encryptedCEK;
ContentCryptoMaterial(Map<String, String> kekMaterialsDescription,
byte[] encryptedCEK,
String keyWrappingAlgorithm,
CipherLite cipherLite) {
this.cipherLite = cipherLite;
this.keyWrappingAlgorithm = keyWrappingAlgorithm;
this.encryptedCEK = encryptedCEK.clone();
this.kekMaterialsDescription = kekMaterialsDescription;
}
/**
* Returns the key wrapping algorithm, or null if the content key is not
* secured via a key wrapping algorithm.
* <p>
* Note if the returned value is
* {@value KMSSecuredCEK#KEY_PROTECTION_MECHANISM}, it means the key is
* protected via KMS rather than a direct key-wrapping algorithm.
*/
String getKeyWrappingAlgorithm() {
return keyWrappingAlgorithm;
}
/**
* Returns true if KMS is used for the content key protection; false
* otherwise.
*/
private boolean usesKMSKey() {
return isKMSKeyWrapped(keyWrappingAlgorithm);
}
/**
* Returns the content crypto scheme.
*/
ContentCryptoScheme getContentCryptoScheme() {
return cipherLite.getContentCryptoScheme();
}
/**
* Returns the given metadata updated with this content crypto material.
*/
ObjectMetadata toObjectMetadata(ObjectMetadata metadata, CryptoMode mode) {
return mode == CryptoMode.EncryptionOnly && !usesKMSKey()
? toObjectMetadataEO(metadata)
: toObjectMetadata(metadata);
}
/**
* Returns the metadata in the latest format.
*/
private ObjectMetadata toObjectMetadata(ObjectMetadata metadata) {
// If we generated a symmetric key to encrypt the data, store it in the
// object metadata.
byte[] encryptedCEK = getEncryptedCEK();
metadata.addUserMetadata(Headers.CRYPTO_KEY_V2,
Base64.encodeAsString(encryptedCEK));
// Put the cipher initialization vector (IV) into the object metadata
byte[] iv = cipherLite.getIV();
metadata.addUserMetadata(Headers.CRYPTO_IV, Base64.encodeAsString(iv));
// Put the materials description into the object metadata as JSON
metadata.addUserMetadata(Headers.MATERIALS_DESCRIPTION,
kekMaterialDescAsJson());
// The CRYPTO_CEK_ALGORITHM, CRYPTO_TAG_LENGTH and
// CRYPTO_KEYWRAP_ALGORITHM were not available in the Encryption Only
// (EO) implementation
ContentCryptoScheme scheme = getContentCryptoScheme();
metadata.addUserMetadata(Headers.CRYPTO_CEK_ALGORITHM,
scheme.getCipherAlgorithm());
int tagLen = scheme.getTagLengthInBits();
if (tagLen > 0)
metadata.addUserMetadata(Headers.CRYPTO_TAG_LENGTH,
String.valueOf(tagLen));
String keyWrapAlgo = getKeyWrappingAlgorithm();
if (keyWrapAlgo != null)
metadata.addUserMetadata(Headers.CRYPTO_KEYWRAP_ALGORITHM,
keyWrapAlgo);
return metadata;
}
/**
* Returns the metadata in backward compatibility (old) format, so it can be
* read by older version of the AWS SDK.
*/
private ObjectMetadata toObjectMetadataEO(ObjectMetadata metadata) {
// If we generated a symmetric key to encrypt the data, store it in the
// object metadata.
byte[] encryptedCEK = getEncryptedCEK();
metadata.addUserMetadata(Headers.CRYPTO_KEY,
Base64.encodeAsString(encryptedCEK));
// Put the cipher initialization vector (IV) into the object metadata
byte[] iv = cipherLite.getIV();
metadata.addUserMetadata(Headers.CRYPTO_IV, Base64.encodeAsString(iv));
// Put the materials description into the object metadata as JSON
metadata.addUserMetadata(Headers.MATERIALS_DESCRIPTION,
kekMaterialDescAsJson());
return metadata;
}
/**
* Returns the json string in backward compatibility (old) format, so it can
* be read by older version of the AWS SDK.
*/
String toJsonString(CryptoMode mode) {
return mode == CryptoMode.EncryptionOnly && !usesKMSKey()
? toJsonStringEO() : toJsonString();
}
/**
* Returns the json string in the latest format.
*/
private String toJsonString() {
Map<String, String> map = new HashMap<String, String>();
byte[] encryptedCEK = getEncryptedCEK();
map.put(Headers.CRYPTO_KEY_V2, Base64.encodeAsString(encryptedCEK));
byte[] iv = cipherLite.getIV();
map.put(Headers.CRYPTO_IV, Base64.encodeAsString(iv));
map.put(Headers.MATERIALS_DESCRIPTION, kekMaterialDescAsJson());
// The CRYPTO_CEK_ALGORITHM, CRYPTO_TAG_LENGTH and
// CRYPTO_KEYWRAP_ALGORITHM were not available in the Encryption Only
// (EO) implementation
ContentCryptoScheme scheme = getContentCryptoScheme();
map.put(Headers.CRYPTO_CEK_ALGORITHM, scheme.getCipherAlgorithm());
int tagLen = scheme.getTagLengthInBits();
if (tagLen > 0)
map.put(Headers.CRYPTO_TAG_LENGTH, String.valueOf(tagLen));
String keyWrapAlgo = getKeyWrappingAlgorithm();
if (keyWrapAlgo != null)
map.put(Headers.CRYPTO_KEYWRAP_ALGORITHM, keyWrapAlgo);
return Jackson.toJsonString(map);
}
private String toJsonStringEO() {
Map<String, String> map = new HashMap<String, String>();
byte[] encryptedCEK = getEncryptedCEK();
map.put(Headers.CRYPTO_KEY, Base64.encodeAsString(encryptedCEK));
byte[] iv = cipherLite.getIV();
map.put(Headers.CRYPTO_IV, Base64.encodeAsString(iv));
map.put(Headers.MATERIALS_DESCRIPTION, kekMaterialDescAsJson());
return Jackson.toJsonString(map);
}
/**
* Returns the key-encrypting-key material description as a non-null json
* string;
*/
private String kekMaterialDescAsJson() {
Map<String, String> kekMaterialDesc = getKEKMaterialsDescription();
if (kekMaterialDesc == null)
kekMaterialDesc = Collections.emptyMap();
return Jackson.toJsonString(kekMaterialDesc);
}
/**
* Returns the corresponding kek material description from the given json;
* or null if the input is null.
*/
@SuppressWarnings("unchecked")
private static Map<String, String> matdescFromJson(String json) {
Map<String, String> map = Jackson.fromJsonString(json, Map.class);
return map == null ? null : Collections.unmodifiableMap(map);
}
/**
* Returns the content encrypting key unwrapped or decrypted. Note if KMS
* is used for key protection, a remote call will be made to KMS to decrypt
* the ciphertext blob.
*
* @param cekSecured
* the content encrypting key in wrapped or encrypted form; must
* not be null
* @param keyWrapAlgo
* key wrapping algorithm; or null if direct encryption instead
* of key wrapping is used
* @param materials
* the client key encrypting key material for the content
* encrypting key
* @param securityProvider
* security provider or null if the default security provider of
* the JCE is used
*/
private static SecretKey cek(byte[] cekSecured, String keyWrapAlgo,
EncryptionMaterials materials, Provider securityProvider,
ContentCryptoScheme contentCryptoScheme, AWSKMS kms) {
if (isKMSKeyWrapped(keyWrapAlgo))
return cekByKMS(cekSecured, keyWrapAlgo, materials, contentCryptoScheme, kms);
Key kek;
if (materials.getKeyPair() != null) {
// Do envelope decryption with private key from key pair
kek = materials.getKeyPair().getPrivate();
if (kek == null) {
throw new SdkClientException("Key encrypting key not available");
}
} else {
// Do envelope decryption with symmetric key
kek = materials.getSymmetricKey();
if (kek == null) {
throw new SdkClientException("Key encrypting key not available");
}
}
try {
if (keyWrapAlgo != null) {
// Key wrapping specified
Cipher cipher = securityProvider == null ? Cipher
.getInstance(keyWrapAlgo) : Cipher.getInstance(
keyWrapAlgo, securityProvider);
cipher.init(Cipher.UNWRAP_MODE, kek);
return (SecretKey) cipher.unwrap(cekSecured, keyWrapAlgo,
Cipher.SECRET_KEY);
}
// fall back to the Encryption Only (EO) key decrypting method
Cipher cipher;
if (securityProvider != null) {
cipher = Cipher.getInstance(kek.getAlgorithm(),
securityProvider);
} else {
cipher = Cipher.getInstance(kek.getAlgorithm());
}
cipher.init(Cipher.DECRYPT_MODE, kek);
byte[] decryptedSymmetricKeyBytes = cipher.doFinal(cekSecured);
return new SecretKeySpec(decryptedSymmetricKeyBytes,
JceEncryptionConstants.SYMMETRIC_KEY_ALGORITHM);
} catch (Exception e) {
throw failure(e, "Unable to decrypt symmetric key from object metadata");
}
}
/**
* Decrypts the secured CEK via KMS; involves network calls.
*
* @return the CEK (in plaintext).
*/
private static SecretKey cekByKMS(byte[] cekSecured, String keyWrapAlgo,
EncryptionMaterials materials,
ContentCryptoScheme contentCryptoScheme, AWSKMS kms) {
DecryptRequest kmsreq = new DecryptRequest()
.withEncryptionContext(materials.getMaterialsDescription())
.withCiphertextBlob(ByteBuffer.wrap(cekSecured));
DecryptResult result = kms.decrypt(kmsreq);
return new SecretKeySpec(copyAllBytesFrom(result.getPlaintext()),
contentCryptoScheme.getKeyGeneratorAlgorithm());
}
/**
* @return a non-null content crypto material.
*/
static ContentCryptoMaterial fromObjectMetadata(
ObjectMetadata metadata,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
boolean keyWrapExpected,
AWSKMS kms) {
return fromObjectMetadata0(metadata, kekMaterialAccessor,
securityProvider, null, NONE, keyWrapExpected, kms);
}
/**
* Factory method to return the content crypto material from the S3 object
* meta data, using the specified key encrypting key material accessor and
* an optional security provider.
*
* @return a non-null content crypto material.
*/
static ContentCryptoMaterial fromObjectMetadata(
ObjectMetadata metadata,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
long[] range,
ExtraMaterialsDescription extra,
boolean keyWrapExpected,
AWSKMS kms) {
return fromObjectMetadata0(metadata, kekMaterialAccessor,
securityProvider, range, extra, keyWrapExpected, kms);
}
/**
* @return a non-null content crypto material.
*/
private static ContentCryptoMaterial fromObjectMetadata0(
ObjectMetadata metadata,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
long[] range,
ExtraMaterialsDescription extra,
boolean keyWrapExpected,
AWSKMS kms) {
// CEK and IV
Map<String, String> userMeta = metadata.getUserMetadata();
String b64key = userMeta.get(Headers.CRYPTO_KEY_V2);
if (b64key == null) {
b64key = userMeta.get(Headers.CRYPTO_KEY);
if (b64key == null)
throw new SdkClientException(
"Content encrypting key not found.");
}
byte[] cekWrapped = Base64.decode(b64key);
byte[] iv = Base64.decode(userMeta.get(Headers.CRYPTO_IV));
if (cekWrapped == null || iv == null) {
throw new SdkClientException(
"Content encrypting key or IV not found.");
}
// Material description
String matdescStr = userMeta.get(Headers.MATERIALS_DESCRIPTION);
final String keyWrapAlgo = userMeta.get(Headers.CRYPTO_KEYWRAP_ALGORITHM);
final boolean isKMS = isKMSKeyWrapped(keyWrapAlgo);
final Map<String, String> core = matdescFromJson(matdescStr);
final Map<String, String> merged = isKMS || extra == null
? core : extra.mergeInto(core);
final EncryptionMaterials materials;
if (isKMS) {
materials = new KMSEncryptionMaterials(
core.get(KMSEncryptionMaterials.CUSTOMER_MASTER_KEY_ID));
materials.addDescriptions(core);
} else {
materials = kekMaterialAccessor == null
? null
: kekMaterialAccessor.getEncryptionMaterials(merged)
;
if (materials == null) {
throw new SdkClientException(
"Unable to retrieve the client encryption materials");
}
}
// CEK algorithm
String cekAlgo = userMeta.get(Headers.CRYPTO_CEK_ALGORITHM);
boolean isRangeGet = range != null;
// The content crypto scheme may vary depending on whether
// it is a range get operation
ContentCryptoScheme contentCryptoScheme =
ContentCryptoScheme.fromCEKAlgo(cekAlgo, isRangeGet);
if (isRangeGet) {
// Adjust the IV as needed
iv = contentCryptoScheme.adjustIV(iv, range[0]);
} else {
// Validate the tag length supported
int tagLenExpected = contentCryptoScheme.getTagLengthInBits();
if (tagLenExpected > 0) {
String s = userMeta.get(Headers.CRYPTO_TAG_LENGTH);
int tagLenActual = Integer.parseInt(s);
if (tagLenExpected != tagLenActual) {
throw new SdkClientException("Unsupported tag length: "
+ tagLenActual + ", expected: " + tagLenExpected);
}
}
}
// Unwrap or decrypt the CEK
if (keyWrapExpected && keyWrapAlgo == null)
throw newKeyWrapException();
SecretKey cek = cek(cekWrapped, keyWrapAlgo, materials,
securityProvider, contentCryptoScheme, kms);
return new ContentCryptoMaterial(merged, cekWrapped, keyWrapAlgo,
contentCryptoScheme.createCipherLite(cek, iv,
Cipher.DECRYPT_MODE, securityProvider));
}
private static KeyWrapException newKeyWrapException() {
return new KeyWrapException(
"Missing key-wrap for the content-encrypting-key");
}
/**
* @return a non-null content crypto material.
*/
static ContentCryptoMaterial fromInstructionFile(
Map<String, String> instFile,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
boolean keyWrapExpected,
AWSKMS kms) {
return fromInstructionFile0(instFile, kekMaterialAccessor,
securityProvider, null, NONE, keyWrapExpected, kms);
}
/**
* Factory method to return the content crypto material from the S3
* instruction file, using the specified key encrypting key material
* accessor and an optional security provider.
*
* @return a non-null content crypto material.
*/
static ContentCryptoMaterial fromInstructionFile(
Map<String, String> instFile,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
long[] range,
ExtraMaterialsDescription extra,
boolean keyWrapExpected,
AWSKMS kms) {
return fromInstructionFile0(instFile, kekMaterialAccessor,
securityProvider, range, extra, keyWrapExpected, kms);
}
/**
* @return a non-null content crypto material.
*/
private static ContentCryptoMaterial fromInstructionFile0(
Map<String, String> instFile,
EncryptionMaterialsAccessor kekMaterialAccessor,
Provider securityProvider,
long[] range,
ExtraMaterialsDescription extra,
boolean keyWrapExpected,
AWSKMS kms) {
// CEK and IV
String b64key = instFile.get(Headers.CRYPTO_KEY_V2);
if (b64key == null) {
b64key = instFile.get(Headers.CRYPTO_KEY);
if (b64key == null)
throw new SdkClientException(
"Content encrypting key not found.");
}
byte[] cekWrapped = Base64.decode(b64key);
byte[] iv = Base64.decode(instFile.get(Headers.CRYPTO_IV));
if (cekWrapped == null || iv == null) {
throw new SdkClientException(
"Necessary encryption info not found in the instruction file "
+ instFile);
}
final String keyWrapAlgo = instFile.get(Headers.CRYPTO_KEYWRAP_ALGORITHM);
final boolean isKMS = isKMSKeyWrapped(keyWrapAlgo);
// Material description
String matdescStr = instFile.get(Headers.MATERIALS_DESCRIPTION);
final Map<String, String> core = matdescFromJson(matdescStr);
final Map<String, String> merged = extra == null || isKMS
? core : extra.mergeInto(core);
EncryptionMaterials materials;
if (isKMS) {
materials = new KMSEncryptionMaterials(
core.get(KMSEncryptionMaterials.CUSTOMER_MASTER_KEY_ID));
materials.addDescriptions(core);
} else {
materials = kekMaterialAccessor == null
? null
: kekMaterialAccessor.getEncryptionMaterials(merged);
if (materials == null) {
throw new SdkClientException(
"Unable to retrieve the encryption materials that originally "
+ "encrypted object corresponding to instruction file "
+ instFile);
}
}
// CEK algorithm
final String cekAlgo = instFile.get(Headers.CRYPTO_CEK_ALGORITHM);
final boolean isRangeGet = range != null;
// The content crypto scheme may vary depending on whether
// it is a range get operation
ContentCryptoScheme contentCryptoScheme = ContentCryptoScheme
.fromCEKAlgo(cekAlgo, isRangeGet);
if (isRangeGet) {
// Adjust the IV as needed
iv = contentCryptoScheme.adjustIV(iv, range[0]);
} else {
// Validate the tag length supported
int tagLenExpected = contentCryptoScheme.getTagLengthInBits();
if (tagLenExpected > 0) {
String s = instFile.get(Headers.CRYPTO_TAG_LENGTH);
int tagLenActual = Integer.parseInt(s);
if (tagLenExpected != tagLenActual) {
throw new SdkClientException("Unsupported tag length: "
+ tagLenActual + ", expected: " + tagLenExpected);
}
}
}
// Unwrap or decrypt the CEK
if (keyWrapExpected && keyWrapAlgo == null)
throw newKeyWrapException();
SecretKey cek = cek(cekWrapped, keyWrapAlgo, materials,
securityProvider, contentCryptoScheme, kms);
return new ContentCryptoMaterial(merged, cekWrapped, keyWrapAlgo,
contentCryptoScheme.createCipherLite(cek, iv,
Cipher.DECRYPT_MODE, securityProvider));
}
/**
* Parses instruction data retrieved from S3 and returns a JSON string
* representing the instruction. Made for testing purposes.
*/
static String parseInstructionFile(S3Object instructionFile) {
try {
return convertStreamToString(instructionFile.getObjectContent());
} catch (Exception e) {
throw failure(e, "Error parsing JSON instruction file");
}
}
/**
* Converts the contents of an input stream to a String
*/
private static String convertStreamToString(InputStream inputStream)
throws IOException {
if (inputStream == null) {
return "";
} else {
StringBuilder stringBuilder = new StringBuilder();
String line;
try {
BufferedReader reader =
new BufferedReader(new InputStreamReader(inputStream,
StringUtils.UTF8));
while ((line = reader.readLine()) != null) {
stringBuilder.append(line);
}
} finally {
inputStream.close();
}
return stringBuilder.toString();
}
}
/**
* Return the cipher lite used for content encryption/decryption purposes.
*/
CipherLite getCipherLite() {
return cipherLite;
}
/**
* Returns the description of the kek materials that were used to encrypt
* the cek.
*/
Map<String, String> getKEKMaterialsDescription() {
return this.kekMaterialsDescription;
}
/**
* Returns an array of bytes representing the encrypted envelope symmetric
* key.
*
* @return an array of bytes representing the encrypted envelope symmetric
* key.
*/
byte[] getEncryptedCEK() {
return this.encryptedCEK.clone();
}
/**
* Recreates a new content crypto material from the current material given a
* new KEK material-descriptions. The purpose is to re-encrypt the CEK under
* a different KEK.
*
* Note network calls are involved if the CEK has been or is to be protected
* by KMS.
*
* @param newKEKMatDesc
* material descriptions for the new KEK; never null
* @param accessor
* used to retrieve the KEK given the corresponding material
* description
* @param targetScheme
* the target crypto scheme to be used for key wrapping, etc.
* @param p
* optional security provider; null means to use the default.
* @throws SecurityException
* if the old and new material description are the same; or if
* the old and new KEK are the same
*/
ContentCryptoMaterial recreate(Map<String, String> newKEKMatDesc,
EncryptionMaterialsAccessor accessor, S3CryptoScheme targetScheme,
Provider p, AWSKMS kms, AmazonWebServiceRequest req) {
if (!usesKMSKey() && newKEKMatDesc.equals(kekMaterialsDescription)) {
throw new SecurityException(
"Material description of the new KEK must differ from the current one");
}
final EncryptionMaterials origKEK;
if (usesKMSKey()) {
origKEK = new KMSEncryptionMaterials(kekMaterialsDescription.get(
KMSEncryptionMaterials.CUSTOMER_MASTER_KEY_ID));
} else {
origKEK = accessor.getEncryptionMaterials(kekMaterialsDescription);
}
EncryptionMaterials newKEK = accessor.getEncryptionMaterials(newKEKMatDesc);
if (newKEK == null) {
throw new SdkClientException(
"No material available with the description "
+ newKEKMatDesc
+ " from the encryption material provider");
}
SecretKey cek = cek(encryptedCEK, keyWrappingAlgorithm, origKEK, p,
getContentCryptoScheme(), kms);
ContentCryptoMaterial output = create(cek, cipherLite.getIV(), newKEK,
getContentCryptoScheme(), // must use same content crypto scheme
targetScheme,
p, kms, req);
if (Arrays.equals(output.encryptedCEK, encryptedCEK)) {
throw new SecurityException(
"The new KEK must differ from the original");
}
return output;
}
/**
* Recreates a new content crypto material from the current material given a
* new KEK encryption materials. The purpose is to re-encrypt the CEK under
* the new KEK.
*
* Note network calls are involved if the CEK has been or is to be protected
* by KMS.
*
* @param newKEK
* encryption materials for the new KEK; must not be null
* @param accessor
* used to retrieve the original KEK given the corresponding
* material description
* @param targetScheme
* the target crypto scheme to use for recreating the content
* crypto material
* @param p
* optional security provider; null means to use the default.
* @throws SecurityException
* if the old and new material description are the same; or if
* the old and new KEK are the same
*/
ContentCryptoMaterial recreate(EncryptionMaterials newKEK,
EncryptionMaterialsAccessor accessor, S3CryptoScheme targetScheme,
Provider p, AWSKMS kms, AmazonWebServiceRequest req) {
if (!usesKMSKey()
&& newKEK.getMaterialsDescription().equals(kekMaterialsDescription)) {
throw new SecurityException(
"Material description of the new KEK must differ from the current one");
}
final EncryptionMaterials origKEK;
if (usesKMSKey()) {
origKEK = new KMSEncryptionMaterials(kekMaterialsDescription.get(
KMSEncryptionMaterials.CUSTOMER_MASTER_KEY_ID));
} else {
origKEK = accessor.getEncryptionMaterials(kekMaterialsDescription);
}
SecretKey cek = cek(encryptedCEK, keyWrappingAlgorithm, origKEK, p,
getContentCryptoScheme(), kms);
ContentCryptoMaterial output =
create(cek, cipherLite.getIV(), newKEK,
getContentCryptoScheme(), // must use same content crypto scheme
targetScheme, // target scheme used to recreate the content crypto material
p, kms, req);
if (Arrays.equals(output.encryptedCEK, encryptedCEK)) {
throw new SecurityException(
"The new KEK must differ from the original");
}
return output;
}
/**
* Returns a new instance of <code>ContentCryptoMaterial</code> for the
* input parameters using the specified content crypto scheme, and the key
* wrapping and secure randomness specified of the specified s3 crypto
* scheme.
*
* Note network calls are involved if the CEK is to be protected by KMS.
*
* @param cek
* content encrypting key; must not be null.
* @param iv
* initialization vector; must not be null.
* @param contentCryptoScheme
* content crypto scheme to be used
* @param targetScheme
* the target s3 crypto scheme to be used for recreating the
* content crypto material by providing the key wrapping scheme
* and mechanism for secure randomness
* @param provider
* optional security provider
*/
static ContentCryptoMaterial create(SecretKey cek, byte[] iv,
EncryptionMaterials kekMaterials,
ContentCryptoScheme contentCryptoScheme,
S3CryptoScheme targetScheme,
Provider provider, AWSKMS kms,
AmazonWebServiceRequest req) {
return doCreate(cek, iv, kekMaterials, contentCryptoScheme,
targetScheme, provider, kms, req);
}
/**
* Returns a new instance of <code>ContentCryptoMaterial</code>
* for the input parameters using the specified s3 crypto scheme.
* Note network calls are involved if the CEK is to be protected by KMS.
*
* @param cek content encrypting key
* @param iv initialization vector
* @param kekMaterials kek encryption material used to secure the CEK;
* can be KMS enabled.
* @param scheme
* s3 crypto scheme to be used for the content crypto material by
* providing the content crypto scheme, key wrapping scheme and
* mechanism for secure randomness
* @param provider optional security provider
* @param kms reference to the KMS client
* @param req originating service request
*/
static ContentCryptoMaterial create(SecretKey cek, byte[] iv,
EncryptionMaterials kekMaterials,
S3CryptoScheme scheme,
Provider provider, AWSKMS kms,
AmazonWebServiceRequest req) {
return doCreate(cek, iv, kekMaterials, scheme.getContentCryptoScheme(),
scheme, provider, kms, req);
}
/**
* Returns a new instance of <code>ContentCryptoMaterial</code> for the
* given input parameters by using the specified content crypto scheme, and
* S3 crypto scheme.
*
* Note network calls are involved if the CEK is to be protected by KMS.
*
* @param cek
* content encrypting key
* @param iv
* initialization vector
* @param kekMaterials
* kek encryption material used to secure the CEK; can be KMS
* enabled.
* @param contentCryptoScheme
* content crypto scheme to be used, which can differ from the
* one of <code>targetS3CryptoScheme</code>
* @param targetS3CryptoScheme
* the target s3 crypto scheme to be used for providing the key
* wrapping scheme and mechanism for secure randomness
* @param provider
* security provider
* @param kms
* reference to the KMS client
* @param req
* the originating AWS service request
*/
private static ContentCryptoMaterial doCreate(SecretKey cek, byte[] iv,
EncryptionMaterials kekMaterials,
ContentCryptoScheme contentCryptoScheme,
S3CryptoScheme targetS3CryptoScheme,
Provider provider,
AWSKMS kms,
AmazonWebServiceRequest req) {
// Secure the envelope symmetric key either by encryption, key wrapping
// or KMS.
SecuredCEK cekSecured = secureCEK(cek, kekMaterials,
targetS3CryptoScheme.getKeyWrapScheme(),
targetS3CryptoScheme.getSecureRandom(),
provider, kms, req);
return wrap(cek, iv, contentCryptoScheme, provider, cekSecured);
}
/**
* Returns a new instance of <code>ContentCryptoMaterial</code> by wrapping
* the input parameters, including the already secured CEK. No network calls
* are involved.
*/
public static ContentCryptoMaterial wrap(
SecretKey cek, byte[] iv,
ContentCryptoScheme contentCryptoScheme,
Provider provider,
SecuredCEK cekSecured) {
return new ContentCryptoMaterial(
cekSecured.getMaterialDescription(),
cekSecured.getEncrypted(),
cekSecured.getKeyWrapAlgorithm(),
contentCryptoScheme.createCipherLite
(cek, iv, Cipher.ENCRYPT_MODE, provider));
}
/**
* Secure the given CEK. Note network calls are involved if the CEK is to
* be protected by KMS.
*
* @param cek content encrypting key to be secured
* @param materials used to provide the key-encryption-key (KEK); or if
* it is KMS-enabled, the customer master key id and material description.
* @param contentCryptoScheme the content crypto scheme
* @param p optional security provider; can be null if the default is used.
* @return a secured CEK in the form of ciphertext or ciphertext blob.
*/
private static SecuredCEK secureCEK(SecretKey cek,
EncryptionMaterials materials, S3KeyWrapScheme kwScheme,
SecureRandom srand, Provider p, AWSKMS kms,
AmazonWebServiceRequest req) {
final Map<String,String> matdesc;
if (materials.isKMSEnabled()) {
matdesc = mergeMaterialDescriptions(materials, req);
EncryptRequest encryptRequest = new EncryptRequest()
.withEncryptionContext(matdesc)
.withKeyId(materials.getCustomerMasterKeyId())
.withPlaintext(ByteBuffer.wrap(cek.getEncoded()))
;
encryptRequest
.withGeneralProgressListener(req.getGeneralProgressListener())
.withRequestMetricCollector(req.getRequestMetricCollector())
;
EncryptResult encryptResult = kms.encrypt(encryptRequest);
byte[] keyBlob = copyAllBytesFrom(encryptResult.getCiphertextBlob());
return new KMSSecuredCEK(keyBlob, matdesc);
} else {
matdesc = materials.getMaterialsDescription();
}
Key kek;
if (materials.getKeyPair() != null) {
// Do envelope encryption with public key from key pair
kek = materials.getKeyPair().getPublic();
} else {
// Do envelope encryption with symmetric key
kek = materials.getSymmetricKey();
}
String keyWrapAlgo = kwScheme.getKeyWrapAlgorithm(kek);
try {
if (keyWrapAlgo != null) {
Cipher cipher = p == null ? Cipher
.getInstance(keyWrapAlgo) : Cipher.getInstance(
keyWrapAlgo, p);
cipher.init(Cipher.WRAP_MODE, kek, srand);
return new SecuredCEK(cipher.wrap(cek), keyWrapAlgo, matdesc);
}
// fall back to the Encryption Only (EO) key encrypting method
Cipher cipher;
byte[] toBeEncryptedBytes = cek.getEncoded();
String algo = kek.getAlgorithm();
if (p != null) {
cipher = Cipher.getInstance(algo, p);
} else {
cipher = Cipher.getInstance(algo); // Use default JCE Provider
}
cipher.init(Cipher.ENCRYPT_MODE, kek);
return new SecuredCEK(cipher.doFinal(toBeEncryptedBytes), null, matdesc);
} catch (Exception e) {
throw failure(e, "Unable to encrypt symmetric key");
}
}
static Map<String, String> mergeMaterialDescriptions(
EncryptionMaterials materials,
AmazonWebServiceRequest req)
{
Map<String,String> matdesc = materials.getMaterialsDescription();
if (req instanceof MaterialsDescriptionProvider) {
MaterialsDescriptionProvider mdp = (MaterialsDescriptionProvider) req;
Map<String, String> matdesc_req = mdp.getMaterialsDescription();
if (matdesc_req != null) {
matdesc = new TreeMap<String, String>(matdesc);
matdesc.putAll(matdesc_req); // request takes precedence
}
}
return matdesc;
}
}