Operation Manual – SSH
H3C S3100 Series Ethernet Switches
Chapter 1 SSH Configuration
1-2
characters called a key, which controls the transformation between plain text and cipher
text, for example, changing the plain text into cipher text or cipher text into plain text.
Figure 1-1
Encryption and decryption
Key-based algorithm is usually classified into symmetric key algorithm and asymmetric
key algorithm.
1.1.3 Asymmetric Key Algorithm
Asymmetric key algorithm means that a key pair exists at both ends. The key pair
consists of a private key and a public key. The public key is effective for both ends,
while the private key is effective only for the local end. Normally you cannot use the
private key through the public key.
Asymmetric key algorithm encrypts data using the public key and decrypts the data
using the private key, thus ensuring data security.
You can also use the asymmetric key algorithm for data signature. For example, user 1
adds his signature to the data using the private key, and then sends the data to user 2.
User 2 verifies the signature using the public key of user 1. If the signature is correct,
this means that the data originates from user 1.
Both Revest-Shamir-Adleman Algorithm (RSA) and Digital Signature Algorithm (DSA)
are asymmetric key algorithms. RSA is used for data encryption and signature,
whereas DSA is used for adding signature.
Note:
Currently, SSH supports both RSA and DSA.
1.1.4 SSH Operating Process
The session establishment between an SSH client and the SSH server involves the
following five stages:
