Operation Manual – SSHH3C S3100 Series Ethernet Switches Chapter 1 SSH Configuration1-2characters called a key, which controls the transformation between plain text and ciphertext, for example, changing the plain text into cipher text or cipher text into plain text.Figure 1-1 Encryption and decryptionKey-based algorithm is usually classified into symmetric key algorithm and asymmetrickey algorithm.1.1.3 Asymmetric Key AlgorithmAsymmetric key algorithm means that a key pair exists at both ends. The key pairconsists 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 theprivate key through the public key.Asymmetric key algorithm encrypts data using the public key and decrypts the datausing the private key, thus ensuring data security.You can also use the asymmetric key algorithm for data signature. For example, user 1adds 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 ProcessThe session establishment between an SSH client and the SSH server involves thefollowing five stages:
