Abstract
In cryptography, quantum information processing can be used to do much more than just key distribution. Simple quantum transformations augmented with the ability to store qubits in a quantum memory are the building blocks of a protocol allowing two parties to communicate secretly by encoding/decoding the exchanged message directly through quantum means, without the need to establish a secret encryption/ decryption key first. Consequently, our quantum mechanical process of securely transmitting a message through a public channel is simpler, cleaner, faster and computationally more efficient than the two-step scenario with a quantum distributed classical key. The probability of catching a potential eavesdropper can be made arbitrarily large by increasing the length of the signature string attached to the message.