SSH keys are a cryptographic authentication mechanism used to securely access remote systems without typing a password each time. In cloud and DevOps workflows, they are foundational for accessing Linux VMs, Git repositories, CI/CD systems, and automation tooling.
Simple Real-World Analogy
Imagine:
- public key = lock
- private key = unique physical key
The server:
- has your lock,
- asks you to unlock something.
Only the matching private key can do it.
But you never hand over the physical key itself.
Why this is secure ?
Even if someone intercepts network traffic:
- they cannot derive the private key.
Because:
- cryptographic signing is one-way.
Why .pem Files Matter in AWS
When AWS gives:
1
mykey.pemThat
.pem file IS your private key.AWS stores the public key on EC2 instances.
During SSH:
- EC2 verifies your
.pemfile cryptographically.
Visually
Your PC Server
Private Key Public Key
| |
| ---- request connection --------> |
| |
| <---- cryptographic challenge -- |
| |
| -- signed response using key --> |
| |
| <------- access granted ---------- |
| ---- request connection --------> |
| |
| <---- cryptographic challenge -- |
| |
| -- signed response using key --> |
| |
| <------- access granted ---------- |
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