Encryption is the process of scrambling data so that it becomes very difficult to unscramble and interpret without the correct key.
Encrypted data is known as ciphertext, and the original interpretable data is known as plaintext. The process of encryption is carried out using a cryptographic algorithm and a key.
Symmetric (Private key) encryption Symmetric encryption, also known as private key encryption, uses the same key to encrypt and decrypt data. This means that the key must also be transferred (known as key exchange) to the same destination as the ciphertext which causes obvious security problems. The key can be intercepted as easily as the ciphertext message to decrypt the data. For this reason asymmetric encryption can be used instead.
Asymmetric (Public key) encryption Asymmetric encryption uses two separate, but related keys. One key, known as the public key, is made public so that others wishing to send you data can use this to encrypt the data. This public key cannot decrypt data. Another private key is known only by you and only this can be used to decrypt the data. It is virtually impossible to deduce the private key from the public key. It is possible that a message could be encrypted using your own public key and sent to you by a malicious third party impersonating a trusted individual. To prevent this, a message can be digitally ‘signed’ to authenticate the sender.