<?php

declare(strict_types=1);

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\StreamInterface;

/**
 * Stream that when read returns bytes for a streaming multipart or
 * multipart/form-data stream.
 */
final class MultipartStream implements StreamInterface
{
    use StreamDecoratorTrait;

    /** @var string */
    private $boundary;

    /** @var StreamInterface */
    private $stream;

    /**
     * @param array  $elements Array of associative arrays, each containing a
     *                         required "name" key mapping to the form field,
     *                         name, a required "contents" key mapping to a
     *                         StreamInterface/resource/string, an optional
     *                         "headers" associative array of custom headers,
     *                         and an optional "filename" key mapping to a
     *                         string to send as the filename in the part.
     * @param string $boundary You can optionally provide a specific boundary
     *
     * @throws \InvalidArgumentException
     */
    public function __construct(array $elements = [], string $boundary = null)
    {
        $this->boundary = $boundary ?: bin2hex(random_bytes(20));
        $this->stream = $this->createStream($elements);
    }

    public function getBoundary(): string
    {
        return $this->boundary;
    }

    public function isWritable(): bool
    {
        return false;
    }

    /**
     * Get the headers needed before transferring the content of a POST file
     *
     * @param string[] $headers
     */
    private function getHeaders(array $headers): string
    {
        $str = '';
        foreach ($headers as $key => $value) {
            $str .= "{$key}: {$value}\r\n";
        }

        return "--{$this->boundary}\r\n".trim($str)."\r\n\r\n";
    }

    /**
     * Create the aggregate stream that will be used to upload the POST data
     */
    protected function createStream(array $elements = []): StreamInterface
    {
        $stream = new AppendStream();

        foreach ($elements as $element) {
            if (!is_array($element)) {
                throw new \UnexpectedValueException('An array is expected');
            }
            $this->addElement($stream, $element);
        }

        // Add the trailing boundary with CRLF
        $stream->addStream(Utils::streamFor("--{$this->boundary}--\r\n"));

        return $stream;
    }

    private function addElement(AppendStream $stream, array $element): void
    {
        foreach (['contents', 'name'] as $key) {
            if (!array_key_exists($key, $element)) {
                throw new \InvalidArgumentException("A '{$key}' key is required");
            }
        }

        $element['contents'] = Utils::streamFor($element['contents']);

        if (empty($element['filename'])) {
            $uri = $element['contents']->getMetadata('uri');
            if ($uri && \is_string($uri) && \substr($uri, 0, 6) !== 'php://' && \substr($uri, 0, 7) !== 'data://') {
                $element['filename'] = $uri;
            }
        }

        [$body, $headers] = $this->createElement(
            $element['name'],
            $element['contents'],
            $element['filename'] ?? null,
            $element['headers'] ?? []
        );

        $stream->addStream(Utils::streamFor($this->getHeaders($headers)));
        $stream->addStream($body);
        $stream->addStream(Utils::streamFor("\r\n"));
    }

    /**
     * @param string[] $headers
     *
     * @return array{0: StreamInterface, 1: string[]}
     */
    private function createElement(string $name, StreamInterface $stream, ?string $filename, array $headers): array
    {
        // Set a default content-disposition header if one was no provided
        $disposition = self::getHeader($headers, 'content-disposition');
        if (!$disposition) {
            $headers['Content-Disposition'] = ($filename === '0' || $filename)
                ? sprintf(
                    'form-data; name="%s"; filename="%s"',
                    $name,
                    basename($filename)
                )
                : "form-data; name=\"{$name}\"";
        }

        // Set a default content-length header if one was no provided
        $length = self::getHeader($headers, 'content-length');
        if (!$length) {
            if ($length = $stream->getSize()) {
                $headers['Content-Length'] = (string) $length;
            }
        }

        // Set a default Content-Type if one was not supplied
        $type = self::getHeader($headers, 'content-type');
        if (!$type && ($filename === '0' || $filename)) {
            $headers['Content-Type'] = MimeType::fromFilename($filename) ?? 'application/octet-stream';
        }

        return [$stream, $headers];
    }

    /**
     * @param string[] $headers
     */
    private static function getHeader(array $headers, string $key): ?string
    {
        $lowercaseHeader = strtolower($key);
        foreach ($headers as $k => $v) {
            if (strtolower((string) $k) === $lowercaseHeader) {
                return $v;
            }
        }

        return null;
    }
}

• [D] Exception
• [F] AppendStream.php
  Delete
• [F] BufferStream.php
  Delete
• [F] CachingStream.php
  Delete
• [F] DroppingStream.php
  Delete
• [F] FnStream.php
  Delete
• [F] Header.php
  Delete
• [F] HttpFactory.php
  Delete
• [F] InflateStream.php
  Delete
• [F] LazyOpenStream.php
  Delete
• [F] LimitStream.php
  Delete
• [F] Message.php
  Delete
• [F] MessageTrait.php
  Delete
• [F] MimeType.php
  Delete
• [F] MultipartStream.php
  Delete
• [F] NoSeekStream.php
  Delete
• [F] PumpStream.php
  Delete
• [F] Query.php
  Delete
• [F] Request.php
  Delete
• [F] Response.php
  Delete
• [F] Rfc7230.php
  Delete
• [F] ServerRequest.php
  Delete
• [F] Stream.php
  Delete
• [F] StreamDecoratorTrait.php
  Delete
• [F] StreamWrapper.php
  Delete
• [F] UploadedFile.php
  Delete
• [F] Uri.php
  Delete
• [F] UriComparator.php
  Delete
• [F] UriNormalizer.php
  Delete
• [F] UriResolver.php
  Delete
• [F] Utils.php
  Delete

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Enhancing Payment Security: The Role of Encryption and Tokenization in Digital Transactions

As digital transactions proliferate, ensuring robust payment security is more critical than ever. Two foundational technologies that are pivotal in this effort are encryption and tokenization.
Encryption is a process that transforms data into a secure format, known as ciphertext, which can only be deciphered using a specific decryption key. This means that even if data is intercepted during transmission, it remains unreadable and protected from unauthorized access. Encryption is essential in safeguarding sensitive payment information, such as credit card details and personal data, during online transactions.
Tokenization, on the other hand, involves substituting sensitive data with unique identifiers or "tokens." These tokens serve as placeholders and have no value outside of the specific transaction context. If intercepted, tokens are meaningless and cannot be used to access the original sensitive data. This method significantly reduces the risk of fraud and data breaches, as the actual payment information is not stored or transmitted.
Together, encryption and tokenization form a powerful security framework. Encryption ensures that data is protected during transmission, while tokenization minimizes the risk of exposing sensitive information by replacing it with secure, non-sensitive tokens.
These technologies are integral to modern payment platforms, providing a robust defense against cyber threats. By implementing advanced encryption and tokenization techniques, businesses can enhance the security of digital transactions, ensuring that users' financial and personal information remains safe. This comprehensive approach not only builds user trust but also fortifies the overall security infrastructure of digital payment systems. As cyber threats evolve, the continued advancement of encryption and tokenization will be crucial in maintaining secure and reliable payment processes.

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• Payment