What is SCP Protocol?

If you transfer files to a server, you're usually either using SFTP or SCP. Both of them operate a little differently from one another, but the core technologies are actually very similar. SCP protocol is a method by which transfers can occur over SSH and through shell. Meanwhile, SFTP is usually used through an SFTP platform. SCP protocol is well-encrypted and robust, though there have been some challenges that have occurred in terms of security. Either SCP or SFTP should be secure for most file transfers, though developers may want to be aware of the differences between the two.

What is SCP Protocol?

What is SCP? Not to be confused with the SCP Foundation (an online creative writing exercise), the SCP Protocol stands for Secure Copy Protocol. This is an SSH-based method of transferring files and data securely. The SCP network protocol relies upon SSH certificate authentication. Those who want to ensure that their files are secure while in transit may want to learn more about SCP protocol, how it is supported, how it works, and whether it's safe.

How does SCP Protocol Work?

Like SFTP, SCP protocol runs on SSH. It uses both encryption and public key authentication to encrypt the files while they are being transferred and to unencrypt them once they have reached the target destination. Two-factor authentication can be used through SCP protocol and SCP protocol is often used for security standards such as HIPAA and PCI-DSS. As a network protocol, everything related to SCP is done under the hood. The programmer or developer themselves uses the shell program to transfer files, and the SCP protocol takes over when actually transferring and encrypting. Consequently, the person uploading files doesn't need to know in-depth about what the SCP protocol does, though they likely should know about it in terms of security.

What is the difference between SFTP and SCP?

Both SFTP and SCP are protocols that are used to keep files safe when being transferred. SFTP Is commonly used when transferring files back and forth between a server, but many people use SCP through shell as well.

So, what is the difference between SFTP and SCP?

There's speed, for one. SCP tends to be much faster than SFTP. SFTP also provides for file management functionality; you usually go through an FTP client that lets you manage and modify your files. SCP doesn't do this; you're only transferring your files. Other differences include the fact that SCP doesn't allow for paused or resumed files. Though the files are going to transfer much faster, they need to transfer all at once. So if you have a big file that you're going to transfer, you should probably do it through SFTP.

So which should you use? Most developers are going to use both tools when they're developing something on a server. Developers will commonly use SFTP if they are transferring large volumes of files, browsing files, and modifying files. SCP will be used when transferring discrete payloads or larger files.

Is SCP safe?

All protocols can have their own functionality issues. There's nothing that's truly completely safe, even the best encryption that someone has now will eventually be broken. In 2019, a vulnerability was discovered in SCP that did make it possible to overwrite files in an SCP target directory. But beyond this, very few issues have been uncovered with the SCP protocol. The largest issue with SCP is that it doesn't have file management capabilities. It is purely used for data transfer. Unlike FTP, which does have file management capabilities.

For most scenarios, both SFTP and SCP are safe, and SCP is not inherently safer than SFTP.

Functionally, developers are going to use SFTP and SCP and both of them can be safe. They can be made safer through the use of two-factor authentication and proper use of public keys, but both of them are very difficult for malicious attackers to break through. While there have been some vulnerabilities discovered with the SCP protocol, they have not been significant, and they have been addressed very quickly.

That being said, SCP and SFTP are not used completely for the same things. SFTP can be used for larger file transfers, for larger volume file transfers, and also for file management. SCP is often used for discrete file transfers, smaller file transfers, and faster file transfers. Because they are both on SSH technology, there shouldn't be any significant concerns with using both technologies interchangeably, or with using one where the other might fail.