An EC2 key pair is a security credential used to securely connect to your Amazon Elastic Compute Cloud (EC2) instances. According to Amazon documentation, it is fundamentally a set of two related keys: a public key and a private key, utilizing public-key cryptography.
Understanding the Concept
The principle of public-key cryptography works as follows:
- Public Key: This key is used to encrypt data. It can be shared openly.
- Private Key: This key is used to decrypt data that was encrypted with the corresponding public key. This key must be kept secret and secure.
In the context of EC2:
- When you create an EC2 instance, you provide the public key from the key pair.
- Amazon stores this public key and associates it with your instance.
- When you want to connect to your EC2 instance, you use the corresponding private key. The instance uses the stored public key to verify your private key and allows you access to the instance.
Key Pair Details
| Feature | Public Key | Private Key |
|---|---|---|
| Purpose | Used to encrypt login data. | Used to decrypt login data and authenticate you. |
| Sharing | Can be shared openly. | Must be kept secret and secure. |
| Storage | Stored by AWS, associated with your instance. | Stored by the user, usually on their local machine. |
Key Pair Usage
- Authentication: The primary use case is to securely authenticate your connections to the EC2 instance, typically via SSH (for Linux instances) or RDP (for Windows instances).
- Security: It ensures that only you, who possess the private key, can log in to your EC2 instances.
- Initial Connection: You use the private key when you first connect to your EC2 instance.
Best Practices for Managing Key Pairs
- Secure Storage: Always store your private key file securely and do not share it.
- Permissions: Ensure your private key file has restricted permissions so only you can access it.
- Regular Audits: Periodically check your key pair management processes and ensure that all keys are secure.
Practical Insight
- When you launch an EC2 instance, you must either create a new key pair or use an existing one.
- You can have multiple key pairs for different instances or purposes.
- You cannot retrieve the private key after creation, so make sure you download it and store it securely.
In short, an EC2 key pair acts as a digital "key" to your cloud servers, allowing secure and authenticated access.
