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ENCRYPT [network~]password :#channel or nick
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Encrypt encrypts talk to a channel or person. This is thought
for allowing improved privacy on irc. You need to handshake
a key with the person you want to talk to encrypted, then
both sides have to set that key to encrypt and decrypt correctly.
Example: 
/ENCRYPT v1s1t0r :john
If john would also set the same password to your nick, you could 
talk encrypted. As encryption algorithms blowfish and idea are used.
If you are using ENCRYPT for a channel, then all people on the channel
have to set the same password.
Example:
/ENCRYPT d0ntkn0w :#leet
See also: DELENCRYPT LISTENCRYPT