PHP中实现Node.js Blowfish CBC解密：常见问题与解决方案

<?php

class Decryptor
{
    public function decrypt($encryptedBuffer)
    {
        ini_set('memory_limit', '1G');

        // Note: The original Node.js code used an empty string as PASSPHRASE.
        // Ensure consistency if a different passphrase is used for encryption.
        $passphrase = ""; // Corresponds to Node.js PASSPHRASE = ""

        // Correct IV: Binary representation of [0, 1, 2, 3, 4, 5, 6, 7]
        $iv = hex2bin('0001020304050607');

        $decryptedBuffer = ''; // Accumulate decrypted data
        $chunkSize = 2048;
        $progress = 0;
        $bufferLength = strlen($encryptedBuffer);

        // Correct loop condition: progress must be less than total length
        while ($progress < $bufferLength) {
            // If the remaining buffer is less than chunkSize, adjust chunkSize
            if (($bufferLength - $progress) < 2048) {
                $chunkSize = $bufferLength - $progress;
            }

            // Correct substr() usage: third parameter is length
            $encryptedChunk = substr($encryptedBuffer, $progress, $chunkSize);

            // Only decrypt every third chunk and only if chunkSize is 2048
            if ($progress % ($chunkSize * 3) === 0 && $chunkSize === 2048) {
                // Correct flags for openssl_decrypt:
                // OPENSSL_RAW_DATA: Disable Base64 decoding
                // OPENSSL_ZERO_PADDING: Disable default PKCS7 padding
                // OPENSSL_DONT_ZERO_PAD_KEY: Handle short keys (PHP 7.1.8+)
                $decryptedChunk = openssl_decrypt(
                    $encryptedChunk,
                    'bf-cbc',
                    $passphrase,
                    OPENSSL_DONT_ZERO_PAD_KEY | OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING,
                    $iv
                );

                if ($decryptedChunk === false) {
                    // Handle decryption error, e.g., throw exception or log
                    error_log("Decryption failed at progress: $progress");
                    // Depending on desired behavior, you might want to break or return
                    return false;
                }
                $decryptedBuffer .= $decryptedChunk;
            } else {
                // If not decrypting this chunk, append it as is (Node.js behavior)
                $decryptedBuffer .= $encryptedChunk;
            }

            $progress += $chunkSize;
        }

        return $decryptedBuffer;
    }
}

// Example Usage (assuming you have an encrypted buffer from Node.js)
// $encryptedData = file_get_contents('path/to/your/encrypted_file');
// $decryptor = new Decryptor();
// $decryptedData = $decryptor->decrypt($encryptedData);
// if ($decryptedData !== false) {
//     file_put_contents('path/to/your/decrypted_file', $decryptedData);
//     echo "File decrypted successfully.\n";
// } else {
//     echo "File decryption failed.\n";
// }

?>