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<?php declare(strict_types = 1); |
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namespace Link0\Bunq\Middleware; |
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use Link0\Bunq\Domain\Keypair\PublicKey; |
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use Psr\Http\Message\ResponseInterface; |
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final class ResponseSignatureMiddleware |
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{ |
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const SIGNATURE_ALGORITHM = OPENSSL_ALGO_SHA256; |
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/** |
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* @var PublicKey |
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*/ |
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private $publicKey; |
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/** |
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* @param PublicKey $serverPublicKey |
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*/ |
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public function __construct(PublicKey $serverPublicKey) |
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{ |
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$this->publicKey = $serverPublicKey; |
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} |
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/** |
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* @param ResponseInterface $response |
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* @return ResponseInterface |
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* @throws \Exception |
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*/ |
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public function __invoke(ResponseInterface $response) |
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{ |
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$header = $response->getHeader('X-Bunq-Server-Signature'); |
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if (isset($header[0])) { |
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$serverSignature = $header[0]; |
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$signatureData = $response->getStatusCode(); |
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$headers = $response->getHeaders(); |
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ksort($headers); |
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foreach ($headers as $header => $values) { |
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// Skip the server signature itself |
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if ($header === 'X-Bunq-Server-Signature') { |
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continue; |
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} |
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// Skip all headers that are not X-Bunq- |
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if (substr($header, 0, 7) !== 'X-Bunq-') { |
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continue; |
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} |
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// Add all header data to verify signature |
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foreach ($values as $value) { |
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$signatureData .= PHP_EOL . $header . ': ' . $value; |
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} |
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} |
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$signatureData .= "\n\n"; |
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$signatureData .= (string) $response->getBody(); |
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$rawSignature = base64_decode($serverSignature); |
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$verify = openssl_verify($signatureData, $rawSignature, $this->publicKey, self::SIGNATURE_ALGORITHM); |
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if ($verify !== 1) { |
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throw new \Exception("Server signature does not match response"); |
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} |
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} |
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return $response; |
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} |
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} |
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link0 /
bunq
