70 lines
3.4 KiB
PHP
70 lines
3.4 KiB
PHP
<?php
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namespace UglyRobot\Infinite_Uploads\Aws\Crypto;
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use UglyRobot\Infinite_Uploads\Aws\Exception\CryptoException;
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use UglyRobot\Infinite_Uploads\Aws\Kms\KmsClient;
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/**
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* Uses KMS to supply materials for encrypting and decrypting data. This
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* V2 implementation should be used with the V2 encryption clients (i.e.
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* S3EncryptionClientV2).
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*/
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class KmsMaterialsProviderV2 extends \UglyRobot\Infinite_Uploads\Aws\Crypto\MaterialsProviderV2 implements \UglyRobot\Infinite_Uploads\Aws\Crypto\MaterialsProviderInterfaceV2
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{
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const WRAP_ALGORITHM_NAME = 'kms+context';
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private $kmsClient;
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private $kmsKeyId;
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/**
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* @param KmsClient $kmsClient A KMS Client for use encrypting and
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* decrypting keys.
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* @param string $kmsKeyId The private KMS key id to be used for encrypting
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* and decrypting keys.
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*/
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public function __construct(\UglyRobot\Infinite_Uploads\Aws\Kms\KmsClient $kmsClient, $kmsKeyId = null)
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{
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$this->kmsClient = $kmsClient;
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$this->kmsKeyId = $kmsKeyId;
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}
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/**
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* @inheritDoc
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*/
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public function getWrapAlgorithmName()
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{
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return self::WRAP_ALGORITHM_NAME;
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}
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/**
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* @inheritDoc
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*/
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public function decryptCek($encryptedCek, $materialDescription, $options)
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{
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$params = ['CiphertextBlob' => $encryptedCek, 'EncryptionContext' => $materialDescription];
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if (empty($options['@KmsAllowDecryptWithAnyCmk'])) {
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if (empty($this->kmsKeyId)) {
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throw new \UglyRobot\Infinite_Uploads\Aws\Exception\CryptoException('KMS CMK ID was not specified and the' . ' operation is not opted-in to attempting to use any valid' . ' CMK it discovers. Please specify a CMK ID, or explicitly' . ' enable attempts to use any valid KMS CMK with the' . ' @KmsAllowDecryptWithAnyCmk option.');
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}
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$params['KeyId'] = $this->kmsKeyId;
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}
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$result = $this->kmsClient->decrypt($params);
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return $result['Plaintext'];
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}
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/**
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* @inheritDoc
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*/
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public function generateCek($keySize, $context, $options)
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{
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if (empty($this->kmsKeyId)) {
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throw new \UglyRobot\Infinite_Uploads\Aws\Exception\CryptoException('A KMS key id is required for encryption' . ' with KMS keywrap. Use a KmsMaterialsProviderV2 that has been' . ' instantiated with a KMS key id.');
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}
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$options = array_change_key_case($options);
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if (!isset($options['@kmsencryptioncontext']) || !is_array($options['@kmsencryptioncontext'])) {
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throw new \UglyRobot\Infinite_Uploads\Aws\Exception\CryptoException("'@KmsEncryptionContext' is a" . " required argument when using KmsMaterialsProviderV2, and" . " must be an associative array (or empty array).");
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}
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if (isset($options['@kmsencryptioncontext']['aws:x-amz-cek-alg'])) {
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throw new \UglyRobot\Infinite_Uploads\Aws\Exception\CryptoException("Conflict in reserved @KmsEncryptionContext" . " key aws:x-amz-cek-alg. This value is reserved for the S3" . " Encryption Client and cannot be set by the user.");
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}
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$context = array_merge($options['@kmsencryptioncontext'], $context);
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$result = $this->kmsClient->generateDataKey(['KeyId' => $this->kmsKeyId, 'KeySpec' => "AES_{$keySize}", 'EncryptionContext' => $context]);
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return ['Plaintext' => $result['Plaintext'], 'Ciphertext' => base64_encode($result['CiphertextBlob']), 'UpdatedContext' => $context];
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}
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}
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