ssh-keygen -b 4096 -t rsa
# press enter
in your ~/.ssh folder you should see id_rsa and id_rsa.pub, which are your private and public keys respectively
in a remote machine add your public key (id_rsa.pub) to the remote machine's ~/.ssh/authenticated_users file
in your local machine run
ssh -i ~/.ssh/id_rsa username@ip-address
in the remote machine's /etc/sshd/sshd_config file, change
PasswordAuthentication yesto
PasswordAuthentication noIn your local machine's ~/.ssh/config file, add the following
Host my_remote
User username
HostName ip-address
IdentityFile ~/.ssh/id_rsaNow you can connect by running
ssh my_remoteAsymmetric encryption is encryption that deals with public and private keys,
They are computationally intensive but do not require a secure connection to exchange "keys", and so they are used primarily as authentication (in SSH)
The general idea is that Bob has a public key known to everybody, and so Alice would encrypt her messsage with bob's public key and send that to Bob.
If an intruder were to pick up the encrypted message, they would need Bob's private key to decrypt, which only Bob has
The important principle in all asymmetric schemes is the "one-way function", which states:
For authentication purposes Bob would send a challenge to alice using Alice's public key and a random number,
Alice would decrypt the encrypted number using the private key, yielding the original number
Alice would encrypt the number using an md5 hash
Bob would encrypt the original number using same hash
if the Alice's hashed number is the same as Bob's resulting hash, then Alice has authenticated herself
![https://c1.staticflickr.com/1/418/18626777534_fc5524c031_o.gif">](https://c1.staticflickr.com/1/418/18626777534_fc5524c031_o.gif">){kind=link}
import hashlib
import hmac
import random
import sha
import string
def random_string(length):
return ''.join([random.choice(string.ascii_letters + string.digits)
for x in range(length)])
m = 'i love pie'
em_md5 = hashlib.md5(message).hexdigest()
z = 'i love pies'
ez_md5 = hashlib.md5(z).hexdigest()
print('md5: "%s" = %s' % (m, em_md5))
print('md5: "%s" = %s' % (z, ez_md5))
e = sha.new(m)
e_sha = e.hexdigest()
salt = random_string(20)
print('salt = %s' % salt)
e = hmac.new(salt, m)
e_hmac = e.hexdigest()
print('hmac: "%s" = %s' % (m, e_hmac))
print('hmac: "%s" = %s' % (z, e_hmac))
hmac uses a private "salt" that it includes in algorithm to further protect against intruders