sha1_file - PHP code example

Using the PHP Function Sha1_file to Calculate the SHA-1 Hash For a File

PHP is a widely used server-side scripting language that supports thousands of built-in functions. Functions are code statements that take input in the form of parameters and process them, then return a value. A parameter is a piece of data or variable that you can pass to the function during runtime using the comma operator.

In the case of the sha1_file function, its main purpose is to calculate the SHA-1 hash for a file. This is a highly secured message digest that can be used to verify the integrity of a file. However, this function can also be exploited to gain access to files on your server. This article will describe the different ways in which this can be done and offer some tips on how to protect against it.

This function takes one string value as an argument, then it generates a 40 character long hash of the string. It also prints the original string value and the generated SHA-1 hash. It is recommended to use this function if you are looking to verify the integrity of a file or if you want to keep track of changes made to a file.

This function can be used to exploit a vulnerability found in the md5_file() function in PHP. This vulnerability allows an attacker to obtain a copy of the md5_file() hash, and then replace it with malicious data. The result would be a reversible md5 hash with the added data. This could lead to the disclosure of sensitive information such as passwords and personal details. This vulnerability can be prevented by ensuring that functions using the md5_file() function are protected with the php://filter wrapper.

sha1_file example

class BasicDataUntouchedTest extends TestCase
{
    public function testBasicDataUntouched(): void
    {
        $file = KernelLifecycleManager::getClassLoader()->findFile(Migration1536233560BasicData::class);
        static::assertIsString($file);

        static::assertSame(
            '803f6b644dc0c3d59b523fa3c02fdbaa28acbbff',
            sha1_file($file),
            'BasicData migration has changed. This is not allowed.'
        );
    }
}

$this->info[$algorithm.'_data'] = false;

                } else {

                    // Get hash of newly created file                     switch ($algorithm) {
                        case 'md5':
                            $this->info[$algorithm.'_data'] = md5_file($temp);
                            break;

                        case 'sha1':
                            $this->info[$algorithm.'_data'] = sha1_file($temp);
                            break;
                    }
                }

                // Clean up                 unlink($empty);
                unlink($temp);

                // Reset abort setting                 ignore_user_abort($old_abort);

            }

    protected function saveBackup($path, $filterString, $operations, $items)
    {
        $backup = new BackupModel();

        $backup->setFilterString($filterString);
        $backup->setOperationString($this->operationsToString($operations));
        $backup->setItems($items);
        $backup->setPath($path);
        $backup->setHash(sha1_file($path));
        $backup->setSize((int) filesize($path));

        $backup->setDate(new DateTime());

        $this->getDqlHelper()->getEntityManager()->persist($backup);
        $this->getDqlHelper()->getEntityManager()->flush($backup);
    }

    /** * Dumps a given table to disc - as only needed columns are exported, this is quite fast * * @param string $table * @param string $name * @param int[] $ids * @param bool $newBackup * * @throws RuntimeException */

/** * @param SplFileObject $partFile * @param string $hash * * @throws Exception * * @return bool */
    private function verifyHash($partFile, $hash)
    {
        if (sha1_file($partFile->getPathname()) !== $hash) {
            // try to delete invalid file so a valid one can be downloaded             @unlink($partFile->getPathname());
            throw new Exception('Hash mismatch');
        }

        return true;
    }

    /** * @param string $partFilePath * @param string $destinationUri */