You need to choose stronger encryption and longer encryption key.
The word cryptography means hidden writing, and it refers to the practice of using encryption to conceal text.. And cryptanalysis studies encryption and encrypted messages, hoping to find the hidden meanings.
Symmetric encryption requires that both parties (sender and receiver) know and have the exact same encryption key. This key is used both for encrypting and decrypting the data. Using the same encryption algorithm means that only those individuals that know or have the same key will be able to read any messages encrypted by the symmetric key.
Encryption
Some messages will require encryption.
It's not.
Asymmetric encryption uses at least 2 keys - hence the asymmetry. The keys for encryption and decryption are not the same, so they are not "symmetric". Usually only 2 keys are used - a public key and a private key. The public key is published to a key registry or sent separately to those the key-pair owner wants to communicate with. The private key is retained by the owner. Messages encrypted with the private key can only be decrypted using the public key. If the source of the public key is trusted, this provides some proof of the source of the message. Messages encrypted with the public key can only be decrypted using the private key - so only the owner of the private key should be able to decrypt messages encrypted with their own private key.
When you reference a "public key" you are implying that the file has been encrypted using "asymmetric cryptography". In asymmetric cryptography, encryption and decryption depend on a key PAIR. The user retains their private key and publishes their public key. Anyone can encrypt a file using the user's public key and send it to them. The only person who should be able to decrypt a file encrypted with that public key is the holder of the private key - which, unless the user has made the mistake of sharing their private key - means that only the original user can decrypt the messages sent to them. Most of the asymmetric encryption algorithms use pretty much the same method to decrypt that was used to encrypt, but use the "other" key from the key pair. Messages encrypted using the private key can only be decrypted using the public key - which provides some authentication that the message indeed came from the holder of the private key. Messages encrypted using the public key can only be decrypted by the holder of the private key, so messages sent to them should be secure.
Enigma
Decoding encrypted enemy radio messages
(BlackBerry Enterprise Server) BES and (Blackberry Messenger Service) BMS allow communication between BlackBerry users in an encrypted form. These messages use complex encryption codes as they travel between the server and the device. (Research In Motion) RIM officials claim that only its users can access these messages and they themselves don't have the access codes.
False. In face, there is virtually no level on security on those messages.