Can MD5 Checksums Reliably Detect Changes in Downloaded PDF Files?

Comparison with MD5 verification and reliable files

Question:

When text extraction cannot be performed, it is a challenge to identify the downloaded PDF file. Is the MD5 verification and a reliable solution?

Answer:

Yes, even if the text and modification date cannot be accessed, the MD5 verification and the reliable method of determining whether the file is changed.

Code fragment:

In C#, use system.security.cryptography.md5 name space. Calculate the MD5 verification and very simple:

The generated byte array can be compared with the previous version of the MD5 hash to detect any changes.

<code class="language-c#">using (var md5 = MD5.Create())
{
    using (var stream = File.OpenRead(filename))
    {
        return md5.ComputeHash(stream);
    }
}</code>

Additional prompt:

To show the hash as a string, use BitConverter to convert it into hexadecimal.

In order to improve efficiency, if you only need to compare hash, avoid using Base64 encoding.
It is recommended to release MD5 for resource management, although it is not absolutely necessary.
• You can establish a reliable mechanism to monitor file changes by using the MD5 verification to ensure accurate records and maintaining file integrity.

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