使用phpseclib3库解密WhatsApp Flows响应时遇到‘Ciphertext representative too long’错误的求助

各位好，我现在在开发WhatsApp Flows的响应解密功能，用的是PHP + CodeIgniter 4框架，搭配phpseclib3库来做加解密操作。但是运行代码的时候一直卡在解密AES密钥这一步，报出Ciphertext representative too long的错误，具体是在这一行：$decryptedAesKey = $rsa->decrypt($encryptedAesKey);

下面是我的示例代码：

private function decryptRequest($body, $privatePem)
{
    $encryptedAesKey   = base64_decode($body['encrypted_aes_key']);
    $encryptedFlowData = base64_decode($body['encrypted_flow_data']);
    $initialVector     = base64_decode($body['initial_vector']);

    $rsa = RSA::load($privatePem)
        ->withPadding(RSA::ENCRYPTION_OAEP)
        ->withHash('sha256')
        ->withMGFHash('sha256');
                    
    $decryptedAesKey = $rsa->decrypt($encryptedAesKey);
        
    if (!$decryptedAesKey) {
        throw new Exception('Decryption of AES key failed.');
    }
    
    $aes = new AES('gcm');
    $aes->setKey($decryptedAesKey);
    $aes->setNonce($initialVector);
    
    $decrypted = $aes->decrypt($encryptedFlowData);
    if (!$decrypted) {
        throw new Exception('Decryption of flow data failed.');
    }
    
    return [
        'decryptedBody' => json_decode($decrypted, true),
        'aesKeyBuffer' => $decryptedAesKey,
        'initialVectorBuffer' => $initialVector,
    ];
}

我已经查阅了WhatsApp官方的加密相关文档，但还是没找到解决这个错误的办法，有没有有经验的朋友能帮我排查下问题出在哪？

备注：内容来源于stack exchange，提问作者iam_furanki