Cipher Android is a cipher tool utilizing a public-key cryptography, RSA .Practically speaking, it is impossible to break messages encrypted with RSA cryptography. You can send messages safe from prying eyes.How To UseYou generate public and private keys.Pass the public key to some of your partners. Keep the private key secret.They encrypt their messages with the public key.They can send the messages to you by any means they like.Only you, who has the private key, can decrypt the encrypted messages. So even if a malicious person gets the encrypted messages and the public key, he or she can never decrypt them.* An SD card is required.