This program is designed to encrypt and decrypt messages using RSA and AES algorithms.
With RSA a message can be encrypted with a public key but it can only be decrypted with a private key.
This means that you can send your public key to another person he can encrypt a message with them but it can only be decrypted using your private key.
In this case one public key corresponds to one private key and a public-private key pair is generated simultaneously.
When using the AES algorithm only a private key is generated; it serves both for encryption and decryption.
There is a limitation on the maximum message length for the RSA algorithm so if you want to encrypt a long message you can either increase the RSA key size or generate an AES key encrypt the message with this key and then encrypt the AES key itself using the recipients public RSA key when In this case only the recipient will be able to decrypt the AES encrypted key with the help of his private key and with the help of it decrypt the message.
I did not include other algorithms supported by Android in the program as they are outdated.
You can add keys that you want to use to the program database.
These keys will be encrypted as well but I do not guarantee that if someone breaks into your phone that that person cannot decrypt them.
For this purpose the program has 3 buttons at the top when you press them the program key database will be erased and the application will close.
When you open the program it will ask you to enter a password.
Be careful because if you enter the password incorrectly once the program will erase all data and remember the entered password as a new one.
When you click on the field with the key a window will open in which it will be fully visible.
When you click on the field of the original message a window will open in which you can edit it.
Key generation and encryption and decryption operations can be time consuming.