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Friday, September 1, 2017
9 - Linux Security: generating a pair of SSH keys (public/private)
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:
https://en.wikipedia.org/wiki/Public-key_cryptography
- Generating a pair of keys (private and public) according to the RSA asymmetric cryptographic algorithm. Notice that a passphrase is optionally asked for:
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
- 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: