What is Cryptography?
Cryptography is the study of secure communication techniques that allow only the sender and intended recipient of a message to view it. The term is derived from the Greek word kryptos, which means hidden. Cryptography uses mathematical techniques to transform data and prevent it from being read or manipulated by unauthorized parties. When transmitting data, the most common use of cryptography is encrypting and decrypting email and other plain-text messages. The simplest method uses the “secret key”/symmetric system where the encrypted data is sent using a secret key, and the encoded message and secret key are sent to the recipient for decryption. In order to avoid the encoded message and secret key being intercepted by a third party, cryptologists have devised a “public key” system where every user has two keys, one being a public key and the other, a private key. A sender requests their intended recipient’s public key, and then they send along their encrypted message. Upon receiving the message, the intended recipient’s private key decodes it.
The National Institute of Standards and Technology (NIST) has been developing cryptographic techniques and technology for fifty years through an open process which brings together industry, government, and academia to develop cryptographic protection approaches.1 Some of the NIST’s public collaborations for developing modern cryptography include advances in the following:
Key establishment. Public key cryptography uses key establishment to establish the data protection keys used by the communicating parties.
Block ciphers. Block ciphers encrypt data in block-sized chunks, rather that one bit at a time, and are useful for encrypting large amounts of data.
Cryptographic hash algorithms. Cryptographic hash algorithms create short digests (hashes) of the information that is being protected. Theses digests are used in many security applications including digital signatures.
Digital signature. A digital signature is an electronic analogue of a written signature that provides assurance that the claimed signatory signed the document, and that the information was not modified post-signature.
Post-quantum cryptography. Post-quantum cryptography is intended to be secure against both quantum and classical computers and deployable without significant changes to existing communication protocols and networks.
Lightweight cryptography. Lightweight cryptography is cryptography that can be used in small devices, such as Internet of Things (IoT) devices, that would be overburdened by current cryptographic algorithms.
Privacy-enhancing cryptography. Privacy-enhancing cryptography is intended to allow research on private data without revealing aspects of the data that could lead to the identification of the owner.
Random bit generation. Random bit generation is a device or algorithm that can produce a sequence of bits that appear to be both unbiased and statistically independent.
1 NIST, 2022, “Cryptography”