Saturday, September 3, 2011
If I run into a password that's been encrypted with the Vigenère cipher and don't care to download a tool or use an online decryptor, here's a quick solution I can use to see what that password is.
Let's say the password I'm wanting to uncover is an NTP authentication key. For instance:
R1#show run | include authentication-key
ntp authentication-key 1 md5 060506324F41 7
Where 060506324F41 is the key I'd like to know the password for.
I create a key chain on the router and paste in the ciphered password:
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#key chain TEST
R1(config-keychain-key)# key-string 7 060506324F41
Follow it up with show key chain TEST:
R1#show key chain TEST
key 1 -- text "cisco"
accept lifetime (always valid) - (always valid) [valid now]
send lifetime (always valid) - (always valid) [valid now]
There you have it. In my case, the password is cisco.