# media-cloud-sync/1.0.1/includes/sdk/s3/Aws/Crypto/DecryptionTraitV2.php

Media Cloud Sync, version 1.0.1. 139 lines.

- Page: https://pluginprobe.com/plugins/media-cloud-sync/1.0.1/code/includes/sdk/s3/Aws/Crypto/DecryptionTraitV2.php
- Raw: https://pluginprobe.com/plugins/media-cloud-sync/1.0.1/raw/includes/sdk/s3/Aws/Crypto/DecryptionTraitV2.php
- Modified: 2024-10-27T10:40:38+00:00

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```php
<?php

namespace Dudlewebs\WPMCS\s3\Aws\Crypto;

use Dudlewebs\WPMCS\s3\Aws\Exception\CryptoException;
use Dudlewebs\WPMCS\s3\GuzzleHttp\Psr7;
use Dudlewebs\WPMCS\s3\GuzzleHttp\Psr7\LimitStream;
use Dudlewebs\WPMCS\s3\Psr\Http\Message\StreamInterface;
trait DecryptionTraitV2
{
    /**
     * Dependency to reverse lookup the openssl_* cipher name from the AESName
     * in the MetadataEnvelope.
     *
     * @param $aesName
     *
     * @return string
     *
     * @internal
     */
    protected abstract function getCipherFromAesName($aesName);
    /**
     * Dependency to generate a CipherMethod from a set of inputs for loading
     * in to an AesDecryptingStream.
     *
     * @param string $cipherName Name of the cipher to generate for decrypting.
     * @param string $iv Base Initialization Vector for the cipher.
     * @param int $keySize Size of the encryption key, in bits, that will be
     *                     used.
     *
     * @return Cipher\CipherMethod
     *
     * @internal
     */
    protected abstract function buildCipherMethod($cipherName, $iv, $keySize);
    /**
     * Builds an AesStreamInterface using cipher options loaded from the
     * MetadataEnvelope and MaterialsProvider. Can decrypt data from both the
     * legacy and V2 encryption client workflows.
     *
     * @param string $cipherText Plain-text data to be encrypted using the
     *                           materials, algorithm, and data provided.
     * @param MaterialsProviderInterfaceV2 $provider A provider to supply and encrypt
     *                                             materials used in encryption.
     * @param MetadataEnvelope $envelope A storage envelope for encryption
     *                                   metadata to be read from.
     * @param array $options Options used for decryption.
     *
     * @return AesStreamInterface
     *
     * @throws \InvalidArgumentException Thrown when a value in $cipherOptions
     *                                   is not valid.
     *
     * @internal
     */
    public function decrypt($cipherText, MaterialsProviderInterfaceV2 $provider, MetadataEnvelope $envelope, array $options = [])
    {
        $options['@CipherOptions'] = !empty($options['@CipherOptions']) ? $options['@CipherOptions'] : [];
        $options['@CipherOptions']['Iv'] = \base64_decode($envelope[MetadataEnvelope::IV_HEADER]);
        $options['@CipherOptions']['TagLength'] = $envelope[MetadataEnvelope::CRYPTO_TAG_LENGTH_HEADER] / 8;
        $cek = $provider->decryptCek(\base64_decode($envelope[MetadataEnvelope::CONTENT_KEY_V2_HEADER]), \json_decode($envelope[MetadataEnvelope::MATERIALS_DESCRIPTION_HEADER], \true), $options);
        $options['@CipherOptions']['KeySize'] = \strlen($cek) * 8;
        $options['@CipherOptions']['Cipher'] = $this->getCipherFromAesName($envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER]);
        $this->validateOptionsAndEnvelope($options, $envelope);
        $decryptionStream = $this->getDecryptingStream($cipherText, $cek, $options['@CipherOptions']);
        unset($cek);
        return $decryptionStream;
    }
    private function getTagFromCiphertextStream(StreamInterface $cipherText, $tagLength)
    {
        $cipherTextSize = $cipherText->getSize();
        if ($cipherTextSize == null || $cipherTextSize <= 0) {
            throw new \RuntimeException('Cannot decrypt a stream of unknown' . ' size.');
        }
        return (string) new LimitStream($cipherText, $tagLength, $cipherTextSize - $tagLength);
    }
    private function getStrippedCiphertextStream(StreamInterface $cipherText, $tagLength)
    {
        $cipherTextSize = $cipherText->getSize();
        if ($cipherTextSize == null || $cipherTextSize <= 0) {
            throw new \RuntimeException('Cannot decrypt a stream of unknown' . ' size.');
        }
        return new LimitStream($cipherText, $cipherTextSize - $tagLength, 0);
    }
    private function validateOptionsAndEnvelope($options, $envelope)
    {
        $allowedCiphers = AbstractCryptoClientV2::$supportedCiphers;
        $allowedKeywraps = AbstractCryptoClientV2::$supportedKeyWraps;
        if ($options['@SecurityProfile'] == 'V2_AND_LEGACY') {
            $allowedCiphers = \array_unique(\array_merge($allowedCiphers, AbstractCryptoClient::$supportedCiphers));
            $allowedKeywraps = \array_unique(\array_merge($allowedKeywraps, AbstractCryptoClient::$supportedKeyWraps));
        }
        $v1SchemaException = new CryptoException("The requested object is encrypted" . " with V1 encryption schemas that have been disabled by" . " client configuration @SecurityProfile=V2. Retry with" . " V2_AND_LEGACY enabled or reencrypt the object.");
        if (!\in_array($options['@CipherOptions']['Cipher'], $allowedCiphers)) {
            if (\in_array($options['@CipherOptions']['Cipher'], AbstractCryptoClient::$supportedCiphers)) {
                throw $v1SchemaException;
            }
            throw new CryptoException("The requested object is encrypted with" . " the cipher '{$options['@CipherOptions']['Cipher']}', which is not" . " supported for decryption with the selected security profile." . " This profile allows decryption with: " . \implode(", ", $allowedCiphers));
        }
        if (!\in_array($envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER], $allowedKeywraps)) {
            if (\in_array($envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER], AbstractCryptoClient::$supportedKeyWraps)) {
                throw $v1SchemaException;
            }
            throw new CryptoException("The requested object is encrypted with" . " the keywrap schema '{$envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER]}'," . " which is not supported for decryption with the current security" . " profile.");
        }
        $matdesc = \json_decode($envelope[MetadataEnvelope::MATERIALS_DESCRIPTION_HEADER], \true);
        if (isset($matdesc['aws:x-amz-cek-alg']) && $envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER] !== $matdesc['aws:x-amz-cek-alg']) {
            throw new CryptoException("There is a mismatch in specified content" . " encryption algrithm between the materials description value" . " and the metadata envelope value: {$matdesc['aws:x-amz-cek-alg']}" . " vs. {$envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER]}.");
        }
    }
    /**
     * Generates a stream that wraps the cipher text with the proper cipher and
     * uses the content encryption key (CEK) to decrypt the data when read.
     *
     * @param string $cipherText Plain-text data to be encrypted using the
     *                           materials, algorithm, and data provided.
     * @param string $cek A content encryption key for use by the stream for
     *                    encrypting the plaintext data.
     * @param array $cipherOptions Options for use in determining the cipher to
     *                             be used for encrypting data.
     *
     * @return AesStreamInterface
     *
     * @internal
     */
    protected function getDecryptingStream($cipherText, $cek, $cipherOptions)
    {
        $cipherTextStream = Psr7\Utils::streamFor($cipherText);
        switch ($cipherOptions['Cipher']) {
            case 'gcm':
                $cipherOptions['Tag'] = $this->getTagFromCiphertextStream($cipherTextStream, $cipherOptions['TagLength']);
                return new AesGcmDecryptingStream($this->getStrippedCiphertextStream($cipherTextStream, $cipherOptions['TagLength']), $cek, $cipherOptions['Iv'], $cipherOptions['Tag'], $cipherOptions['Aad'] = isset($cipherOptions['Aad']) ? $cipherOptions['Aad'] : null, $cipherOptions['TagLength'] ?: null, $cipherOptions['KeySize']);
            default:
                $cipherMethod = $this->buildCipherMethod($cipherOptions['Cipher'], $cipherOptions['Iv'], $cipherOptions['KeySize']);
                return new AesDecryptingStream($cipherTextStream, $cek, $cipherMethod);
        }
    }
}

```