Capstone is a

United States government The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United States, a federal republic located primarily in North America, composed of 50 states, a city within a fede ...

long-term project to develop

cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

standards for public and government use. Capstone was authorized by the

Computer Security Act of 1987 The Computer Security Act of 1987, Public Law No. 100-235 (H.R. 145), (Jan. 8, 1988), was a United States federal law enacted in 1987. It was intended to improve the security and privacy of sensitive information in federal computer systems and to e ...

, driven by the

National Institute of Standards and Technology The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

(NIST) and the

National Security Agency The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collecti ...

(NSA); the project began in 1993.

Project

The initiative involved four standard algorithms: a data

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...

algorithm called Skipjack, along with the

Clipper chip The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured "voice and data messages" with a built-in backdoor that was intended to "allow Federal, State, ...

that included the Skipjack algorithm, a digital signature algorithm,

Digital Signature Algorithm The Digital Signature Algorithm (DSA) is a Public-key cryptography, public-key cryptosystem and Federal Information Processing Standards, Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular e ...

(DSA), a hash function,

SHA-1 In cryptography, SHA-1 (Secure Hash Algorithm 1) is a cryptographically broken but still widely used hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest – typically rendered as 40 hexadecima ...

, and a

key exchange Key exchange (also key establishment) is a method in cryptography by which cryptographic keys are exchanged between two parties, allowing use of a cryptographic algorithm. If the sender and receiver wish to exchange encrypted messages, each ...

protocol. Capstone's first implementation was in the

Fortezza Fortezza is an information security system that uses the Fortezza Crypto Card, a PC Card-based security token. It was developed for the U.S. government's Clipper chip project and has been used by the U.S. Government in various applications. Ea ...

PCMCIA card In computing, PC Card is a configuration for computer parallel communication peripheral interface, designed for laptop computers. Originally introduced as PCMCIA, the PC Card standard as well as its successors like CardBus were defined and develop ...

. All Capstone components were designed to provide 80-bit security. The initiative encountered massive resistance from the cryptographic community, and eventually the US government abandoned the effort. The main reasons for this resistance were concerns about Skipjack's design, which was classified, and the use of key escrow in the Clipper chip.

References

External links

EFF archives on Capstone
{{crypto-stub National Security Agency encryption devices History of cryptography