Asymmetrical encryption uses a pair of keys, public and private. The public key is used to encrypt the message and may be shared with anyone. The private key is used to decrypt the message, hence it must be protected. Asymmetrical encryption requires high computing power of both the encrypting and decrypting device, which leads to a relatively large delay caused by the process of encryption and decryption on cryptographic devices. This encryption method is therefore not suitable for securing communication links or communication services which require fast data transfer with a short lag for real-time communications. Another disadvantage of asymmetrical encryption is the method of creating a public key which does not allow for the creation of keys like with the symmetrical encryption method, without the need for transmitting a key to the other party.