Friday, September 1, 2017

9 - Linux Security: generating a pair of SSH keys (public/private)


- Layout for this exercise:

- Public key cryptography or asymmetrical cryptography is a cryptographic system that uses a pair of keys.

- Public keys may be disseminated widely, and private keys are known only to the owner. 

- This accomplishes two functions: authentication, which is when the public key is used to verify that a holder of the paired private key sent the message, and encryption, whereby only the holder of the paired private key can decrypt the message encrypted with the public key:

- Generating a pair of keys (private and public) according to the RSA asymmetric cryptographic algorithm. Notice that a passphrase is optionally asked for:

- The two keys are stored into the folder .ssh:

- The private key:

- The public key:

- Checking the IP:

- Copying the  public key so that locally available keys are used to authorize logins on remote machines:

- Trying the SSH connection:

- The passphrase is required to unlock the private key:

- Entering the passphrase (without password !!) the SSH connection is successful:

- Let's see that the public key was actually added:

- The authorized key matches the public key (id_rsa)obtained previously:

- Connecting from other server: