Algorithm And Key; Asymmetric Key Algorithm - H3C S3100-52P Operation Manual

Operation Manual – SSH
H3C S3100-52P Ethernet Switch
Caution:
Currently, the device that serves as an SSH server supports two SSH versions:
SSH2 and SSH1, and the device that serves as an SSH client supports only SSH2.
Unless otherwise noted, SSH refers to SSH2 throughout this document.

1.1.2 Algorithm and Key

Algorithm is a set of transformation rules for encryption and decryption. Information
without being encrypted is known as plain text, while information that is encrypted is
known as cipher text. Encryption and decryption are performed using a string of
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.
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Chapter 1 SSH Configuration