This is different to symmetric encryption where the same key is used to encrypt and decrypt.
Asymmetric encryption uses a special pairing of keys:
- Public key – anyone can ask for a copy
- Private key – remains private on the computer, never sent
- Both needed to decrypt
- Only public key is needed to encrypt
Because both keys are needed to decrypt, it doesn’t matter who sees the public key – all they can do is encrypt data with it!
SSL uses a combination of symmetric and asymmetric encryption where:
- Asymmetric encryption resolves the key distribution problem, so that
- Data can be transmitted using symmetric encryption
- A symmetric key is encrypted by the sending computer using the public key sent by the receiving computer (usually via SSL certificate)
- The encrypted symmetric key is sent to the receiving computer (unreadable if intercepted)
- Using the stored private key, and the readily available public key, the receiving computer decrypts the symmetic key
- Now, both computers have the same symmetric key ready for secure encrypted data transmission