Authentication Methods Overview

Password Authentication

• Users authenticate with a username and password.

• Simple to implement but less secure if passwords are weak or intercepted.

Certificate-based Authentication

• Utilizes digital certificates signed by a trusted Certificate Authority (CA).

• Scalable and manageable in large environments, offers higher security assurance.

• Example: PEM file(private key).

• Process:

  • Download the PEM file when creating the EC2 instance.

  • Connect to the remote server using:

      ssh -i <path of .pem file to access> <username of AMI>@<ip address of remote server>
    

• scp (Secure Copy Protocol):

    scp -i <path of .pem file to access> <path of file you are transferring from your local machine> <username of AMI>@<ip address of remote server>:<directory on the remote server where the file will be copied>
  

Public Key Authentication

• Uses asymmetric cryptography with a key pair: public (server-side) and private (client-side) keys.

• More secure than passwords, especially with strong key management.

• SSH-KEYGEN:
  - Public Key: This can be freely shared with others. It's used to encrypt data that can only be decrypted by the corresponding private key.

  - Private Key: This should be kept secret. It's used to decrypt data encrypted with the public key and proves your identity for SSH logins.

• Process:

  • Client:

    • Generate SSH keys using

        ssh-keygen
      

    • Navigate to the .ssh directory and copy the public key (e.g., id_rsa.pub).

  • Remote Server:

    • Generate SSH keys using

        ssh-keygen
      

    • Navigate to the .ssh directory.

    • Paste the client's public key into the authorized_keys file.

  • Final Step in Client:

    •       ssh <private ip of remote server if within VPC, otherwise public ip of remote server>
      

Keyboard-Interactive Authentication

• The server customizes prompts to challenge the client.

• Often used for multi-factor authentication with OTPs or biometric data.

Biometric Authentication

• Uses biological traits like fingerprints or facial recognition for verification.

• Provides strong security but requires specialized hardware and software.

Token-based Authentication

• Uses physical tokens (e.g., smart cards or USB tokens) with digital certificates or OTPs.

• Ensures strong authentication and protects against unauthorized access.

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