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你需要知道的關於 SSH 密鑰的一切

SSH keys are part of a protocol that guarantees the protection of IT systems during data transfer between servers and computers and are used by organizations that need to communicate with systems and manage them securely. 

However, most companies manage their SSH keys improperly, which puts their security at risk. For this reason, we prepared this article, in which we cover the importance of the SSH protocol, its history, benefits, how it works, and much more. Read it until the end and understand better about this subject.

The use of SSH keys is an extremely important measure for organizations that need to communicate and manage systems securely. Nevertheless, for this procedure to really provide the necessary security, it is essential to adopt good practices.

We start our text by sharing two news stories about breached SSH credentials. The first case took place in 2019, but it was only identified in 2020, and it involves the website host company GoDaddy.

The domain registrar announced it had become the target of a breach that affected the SSH credentials of approximately 28,000 users at the time. A malicious actor would have bypassed its security systems and accessed SSH login data hosted on its servers.

There were no major issues, but its users have been notified about it. In addition, the company reset the usernames and passwords that were exposed and blocked the unauthorized party.

In 2021, GitHub received a warning from developer Axosoft about the vulnerability of a dependency on their git GUI client – GitKraken, which was generating weak keys. Therefore, it revoked all keys generated by vulnerable versions of the client used on

Other possibly weak keys generated by other clients that could have used the same vulnerable dependency were also revoked. The company still needed to implement safeguards to prevent vulnerable versions of GitKraken from adding weak SSH keys created by older versions.

These two facts demonstrate that large organizations have managed the SSH protocol improperly, creating vulnerability for their systems.

Therefore, we prepared a special content, in which we show you everything you need to know about SSH keys. To facilitate your understanding, we divided our text into the following topics: 

  1. SSH Protocol: What is It and Why is It Important?
  2. Learn About the History of SSH
  3. Learn About the Benefits of SSH Key Authentication
  4. What Are the SSH Key Types?
  5. Learn How an SSH Key is Generated
  6. How SSH Key Access Works
  7. How to Strengthen the Security of SSH Keys
  8. SSH Key Encryption Categories
  9. Data Related to the Security of SSH Keys
  10. Management of SSH Keys by senhasegura
  11. Conclusion

Follow the whole content!

1. SSH Protocol: What is It and Why is It Important?

Currently used in servers and datacenter environments, SSH consists of a protocol that allows the transmission of data, enabling the encapsulation of applications.

With SSH keys, system administrators and application developers have interactive access to remote systems securely. It is a feature widely used in database updates, backups, automated systems management, and system health monitoring applications.

In practice, SSH keys play a very important role in the functioning of automated digital networks used in data centers and businesses in general.

This solution guarantees encrypted connections with other systems, platforms, and networks that can be distributed in different environments, remote or in the cloud.

SSH keys replace isolated security techniques that are useful for encrypting data transfers. However, this use needs to be properly protected, analyzed periodically, documented, and managed systematically. If this process is not taken seriously, the security of the entire environment is at risk. 

2. Learn About the History of SSH

The first version of the SSH protocol was created in the 1990s by the researcher Tatu Ylonen at the University of Helsinki. At the time, a sniffing attack on the university’s network was discovered, capable of intercepting and recording network traffic and revealing usernames and their passwords to malicious actors.

As a result, thousands of credentials were breached. For this reason, the researcher started looking for ways to make networks more secure, developing the SSH protocol.

Currently, SSH keys are used to log in from one system to another remotely. Also, the security provided by encryption makes it possible to perform functions such as: issuing remote commands and managing network infrastructure and other vital system components remotely. Therefore, this tool is essential nowadays, characterized by the trend of remote work.

Before using SSH keys, it is necessary to install some software: while remote systems must necessarily have software called SSH daemon, the system used to issue commands and manage remote servers requires software known as an SSH client. This is the only way to create an appropriate communication channel using the SSH protocol.

3. Learn About the Benefits of SSH Key Authentication

SSH keys have the function of encrypting traffic between server and client. In practice, this means that if someone decides to spy on this traffic, they will not be able to decrypt the data properly. 

This solution also provides protection against brute force attacks and attack vectors used to access remote machines. With public-key encryption, there is no need to send passwords over the network, which provides more security.

Another advantage of SSH keys is the possibility of keeping a company in compliance with security regulations, but for this, it is necessary to generate, store, manage, and remove them following certain guidelines that guarantee the necessary protection.

There is a massive amount of SSH keys that can be used at any time by an organization. Therefore, it is recommended to use software to manage them and reduce risks.

4. What Are the SSH Key Types?

SSH keys provide security and cost savings to cloud and other computer-dependent services if managed properly.

This feature has a similar function to that of passwords, since they grant access, controlling who will access the system. To perform this management, it is necessary to adopt security policies, as it must be done with user accounts and passwords. 

We also emphasize it is the control of SSH keys that provides continuous availability, confidentiality, and integrity to the systems, as long as public-key encryption is used. 

These keys are categorized according to their function as: user keys, host keys, and session keys. Check it out:

  • User Keys

Here, we are talking about authorized and identity keys, used to grant login access to users. Its authentication mechanism is known as public-key authentication. 

These identity keys are used by SSH clients to allow users to authenticate when logging into SSH servers. 

  • Host Keys

This type of key is intended to authenticate computers, preventing man-in-the-middle attacks. This authentication is certificate-based and can be very useful for organizations.

These authentication keys must secure all connections, and one of the characteristics of SSH is to remember the host’s key when connecting to it for the first time. 

  • Session Keys

Session keys have the function of encrypting most data on a connection. This key is negotiated during connection initialization. It is then used with symmetric encryption algorithm and an authentication code algorithm that ensure data protection.

5. Learn How an SSH Key is Generated

They are generated in pairs that bring together a “public” and a “private” SSH key. In this process, complex algorithms are used, so that it is unlikely to falsify or identify the private key, even if the public key is known. 

Thus, one must keep the private key secret, being used only by an authorized user. Public keys can be shared with others. 

To generate SSH keys, one needs to enter information such as passwords. Generally, short phrases are used to generate public and private keys.

About Version 2 Limited
Version 2 Limited is one of the most dynamic IT companies in Asia. The company develops and distributes IT products for Internet and IP-based networks, including communication systems, Internet software, security, network, and media products. Through an extensive network of channels, point of sales, resellers, and partnership companies, Version 2 Limited offers quality products and services which are highly acclaimed in the market. Its customers cover a wide spectrum which include Global 1000 enterprises, regional listed companies, public utilities, Government, a vast number of successful SMEs, and consumers in various Asian cities.

About Senhasegura
Senhasegura strive to ensure the sovereignty of companies over actions and privileged information. To this end, we work against data theft through traceability of administrator actions on networks, servers, databases and a multitude of devices. In addition, we pursue compliance with auditing requirements and the most demanding standards, including PCI DSS, Sarbanes-Oxley, ISO 27001 and HIPAA.