Key pairs are a set of security credentials for identity authentication when you remotely log in to ECSs.
A key pair consists of a public key and a private key. Key Pair Service (KPS) stores the public key and you store the private key. If you have imported a public key into a Linux ECS, you can use the corresponding private key to log in to the ECS without a password. You do not need to worry about password interception, cracking, or leakage.
When purchasing an ECS, you are advised to select the key pair login mode. For Windows ECSs, key pairs are required to decrypt the passwords so that you can use the decrypted password to log in.
You can directly use a key pair to log in a Linux ECS.
You can use the key pair to obtain a password for login. The password is randomly generated and is more secure.
For details, see Obtaining the Password for Logging In to a Windows ECS.
You can create a key pair or use an existing one for remote login authentication.
After the key pair is created, import the key pair following the instructions provided in Importing a Key Pair so that you can use it.
If an existing key pair (created using PuTTYgen, for example) is available, you can import the public key by referring to Importing a Key Pair on the management console to let the system maintain your public key.
If the public key of the existing key pair is stored by clicking Save public key on PuTTY Key Generator, the public key cannot be imported to the management console.
If you want to use this existing key pair for remote login, see Why Does a Key Pair Created Using puttygen.exe Fail to Be Imported on the Management Console?