Cryptography Standards and Infrastructures for the Twenty-First Century 
     
The Internet is opening up new ways for consumers, industry, and governments to conduct business and to exchange
information electronically. Electronic ordering and payments can be handled efficiently and conveniently over the
network. Electronic mail and informational Web pages have become institutional resources. Yet the full benefits of
electronic commerce and information exchanges will not be realized until users have sufficient trust and confidence in the
security and privacy of their information. 

 The President's Commission on Critical Infrastructure Protection recently issued a report on the threats to
telecommunications, energy, banking and finance, and other systems critical to the government and economy of the U.S.
The Commission warned that people may not be willing to use the Internet for commerce if they do not have confidence
that their communications and data are safe from unauthorized access or modification. Further, the Commission noted
that secure and reliable telecommunications networks must have effective ways for authenticating information and
assuring the confidentiality of information. There is no single technology or technique that will produce the needed
security and reliability of networks. A range of technologies, including cryptography, improved identification and
authentication technologies, and firewalls, will be required, along with trusted encryption key and security management
infrastructures. 

 Cryptography has had, and will continue to have, an important role in protecting information both within a computer
system and when information is sent over the Internet and other unprotected communications channels. Cryptography
serves many functions in secure business transactions by providing ways to assure data confidentiality, data integrity,
authentication of message originator, user authentication, electronic certification of data, and nonrepudiation. 

 This bulletin reports on the progress being made by NIST and by its government and industry partners to advance the
development of electronic commerce systems in which users will have confidence. There are efforts underway to update
existing standards for cryptography; to develop new and stronger forms of encryption; and to create infrastructures that
will support safe electronic transactions in future networks. 

 Data Encryption Standard 

 The two basic components of cryptography are the algorithm or cryptographic methodology used, and the key. In
modern systems, algorithms are complex mathematical formulae and keys are strings of bits. The Data Encryption
Standard (DES), issued in 1977, provides an encryption algorithm for protecting federal unclassified information from
unauthorized disclosure or undetected modification during transmission or while in storage. The standard is based on
secret key cryptography. The algorithm is publicly known; the key system is symmetric with the same key used for
encrypting and decrypting information, and the keys must be kept secret. The standard was initially issued for
government use. It was subsequently adopted as a voluntary industry standard (American National Standard X3.92
1981/R1987) and has been widely implemented by the private sector. It is based on the work of the International
Business Machines Corporation. 

 Under the provisions of the DES, NIST is required to conduct a review every five years to determine whether the
cryptographic algorithm specified by the standard should be affirmed, revised, or withdrawn. The first review resulted in
the reaffirmation of the standard in 1983; the standard was again reaffirmed in 1988 following a second review; as a
result of the third review, which was completed in 1993, the DES was reaffirmed for use through 1998 as Federal
Information Processing Standard (FIPS) 46-2. 

 Triple DES. A more secure method for using the DES algorithm in three operations, called Triple DES, has been
developed by the private sector. Triple Data Encryption Algorithm mode of operations and implementation methods have
been documented and specified as draft American National Standards (X9.52 and X9.65) by Accredited Standards
Committee X9 for Financial Services. This committee develops cryptography and public key infrastructure standards for
the banking community. Federal organizations that need security beyond that provided by the DES can use these
standards. 

 Strength of the DES. The continued security of the DES has been questioned as the result of various attempts to
break the algorithm. The security provided by DES cryptographic systems depends on the mathematical soundness of the
algorithm, length of the keys, key management, mode of operation, and implementation. It is expected that people will
continue to try to attack the DES, and other encryption algorithms as well. Successful attacks on the DES have been brute
force attacks, which have tried all possible keys for a given encryption until the correct key is found. Motivated by a
well-publicized competition in 1997, successful attackers organized teams of people and tens of thousands of computers
that worked for months to break one message. In July 1998, the New York Times reported that a group of computer
experts had succeeded in breaking a DES-encoded message by building a cracking machine costing $250,000. The
machine, consisting of 27 boards each holding 64 chips, took 56 hours to recover a DES key and decipher an encrypted
message. This most recent attack appears to demonstrate that a single determined attacker can develop an effective DES
cracking machine. In some cases, the attack may not pose an immediate or significant threat. However, organizations
may wish to consider making the transition to the use of Triple DES, matching the strength of the protective measures
against the associated risks. 

 In consultation with other organizations, NIST is developing plans for its next steps concerning the DES. One option
under consideration is to revise the applicability provisions of the standard to recommend that agencies use multiple DES
iterations, such as Triple DES, to protect highly sensitive data and data that requires long-term protection for
confidentiality. 

 Escrowed Encryption Standard 

 FIPS 185, Escrowed Encryption Standard, specifies the SKIPJACK algorithm which federal agencies can use for
protecting the confidentiality of data. When originally issued, the SKIPJACK algorithm and the Key Exchange
Algorithm used with SKIPJACK were classified secret. Recently, the Department of Defense announced that it had
declassified both algorithms in an effort to encourage the development of reasonably priced and interoperable computer
protection products for the Defense Message System and other Department of Defense applications. 

 Review of FIPS 140-1, Security Requirements for Cryptographic Modules 

 Issued in 1994, FIPS 140-1 specifies the overall requirements for the design and implementation of modules that use
cryptographic algorithms and methods. The standard identifies requirements for four security levels for cryptographic
modules to provide for different sensitivity levels of data from low value to high value, and for many different
applications. Like the DES, this standard also calls for a review by NIST every five years. 

 The first planned review of FIPS 140-1 will be announced in the Federal Register later this year. Public comments will
be solicited on the continued usefulness of the standard and on any requirements for revisions that may be needed to meet
the challenges of technological and economic change. 

 NIST has established a program to validate cryptographic modules for correct implementation of cryptography
standards. This effort is carried out under the auspices of the National Voluntary Laboratory Accreditation Program
(NVLAP), and in cooperation with the Communications Security Establishment (CSE) of the Government of Canada. A
list of validated products is maintained by NIST and is available on the Web site listed at the end of this bulletin. 

 Expansion of the Digital Signature Standard 

 Public key cryptography uses two keys: a private key and a public key. The private key cannot be derived from the
public key. FIPS 186, Digital Signature Standard (DSS), specifies the Digital Signature Algorithm (DSA), that is used in
conjunction with FIPS 180-1, Secure Hash Algorithm, for applications requiring the authentication of data integrity and
the identity of the signer. FIPS 186 provides cryptographic techniques based on public key cryptography for generating
and verifying electronic signatures, which can be used to verify the origin and contents of a message. FIPS 180-1
specifies a Secure Hash Algorithm (SHA-1) which can be used to generate a condensed representation of a message
called a message digest. These techniques, that were developed for the federal government, are also implemented in
commercial products and used by both the public and private sectors. 

 Last year, NIST proposed expanding the Digital Signature Standard to include additional signature algorithms that the
federal government could endorse to authenticate electronic information and transactions and to assure high levels of
integrity. Most of the federal organizations responding to our request for comments supported the addition of alternative
signature algorithms. We have identified RSA and Elliptic Curve Cryptography technology as potential new algorithms
for inclusion in a revised FIPS 186. Both techniques have been proposed as voluntary industry standards. Seeking to be
consistent with the actions in the voluntary standards community, we are awaiting the completion of the industry
standardization processes before proceeding with the revision of the FIPS to include the RSA technique and Elliptic
Curve Cryptography technology. When approved by the American National Standards Institute (ANSI) as voluntary
industry standards, we intend to take appropriate steps to gain approval and to advise federal agencies that they can use
these standards in addition to the DSA. 

 Development of the Advanced Encryption Standard 

 Last year, we also announced that we would begin a multi-year project to develop an Advanced Encryption Standard
(AES) which would provide cryptographic protection for data well into the next century. Planned as a government and
industry cooperative effort, the AES project has elicited considerable public attention and involvement. More than fifty
public comments were received on the minimum acceptability requirements and the criteria that were drafted to evaluate
candidate algorithms for the AES. More than 75 individuals from industry and government agencies attended a workshop
held in April 1997 to refine the requirements and criteria. 

 A call for candidate algorithms based on the jointly developed requirements and criteria was announced in the Federal
Register (September 12, 1997, Volume 62, Number 177, Pages 48051-48058). By the submission deadline of June
15, 1998, we had received 21 submissions, including many from U.S. industry. Fifteen of these met NIST's
submission requirements and minimum acceptability criteria. The fifteen candidate algorithms were announced at a
conference held in Ventura, California, on August 20-22, 1998. We plan to work with the cryptographic research
community in evaluating the candidate proposals. After reviews and tests of implementations for efficiency, we will
narrow the candidate proposals to approximately five, and invite further review and analysis. The AES is planned to be
an unclassified, publicly disclosed symmetric key encryption algorithm that will be available royalty-free worldwide. 

 Key Agreement or Exchange 

 Cryptographic services depend on the secure generation and distribution of keys (public and private). Key management
services are needed to support authentication, integrity, and confidentiality of information. NIST has solicited comments
on technologies that could be considered for the design and implementation of federal key agreement and exchange
systems for public key-based cryptography. Key exchange technologies under consideration are RSA, Elliptic Curve,
and Diffie-Hellman technologies to give federal organizations broad flexibility in using cryptographic systems. We will
await the completion of the voluntary standards processes before proposing a federal standard for key agreement and
exchange. 

 Public Key Infrastructure (PKI) 

 Several activities are underway to support the development of a public key infrastructure which provides the means to
bind the public keys used in cryptographic functions to their owners and to distribute keys in large heterogeneous
networks. The use of PKI technology can help to increase confidence in electronic transactions and allow parties without
prior knowledge of each other to conduct verifiable transactions. 

 PKI Pilots. NIST is working with the Federal PKI Steering Committee (a committee established by the Government
Information Technology Services [GITS] Board) to promote the consideration and use of public key technology by
federal agencies in the performance of intra-agency and interagency business and in transactions with trading partners and
the public. Established under Executive Order 13011, GITS is conducting demonstration projects, pilots, and
proof-of-concept projects in support of the Administration's National Partnership for Reinventing Government (formerly
the National Performance Review) initiative to make government work better and cost less by reengineering through
information technology. NIST also works with industry groups including the Internet Engineering Task Force PKIX
Working Group and the Accredited Standards Committee X9. 

 Interoperability Specifications. In conjunction with ten research partners under a cooperative research and
development agreement (CRADA), NIST completed a Minimum Interoperability Specification for Public Key
Infrastructure Components (MISPC). Based on analysis of implementations of PKI components provided by the
CRADA participants, the specification provides a minimal set of features, transactions, and data formats for various
certificate management components that make up a PKI. The MISPC can be used by industry and government
organizations in acquiring PKI components and services. NIST is developing a laboratory-based reference
implementation of the MISPC as a proof of concept and to enable developers of PKI systems to test their
implementations. Future laboratory work will be directed toward developing a test suite to provide the means for the
validation of the interoperability of PKI systems. 

 PKI product developers are beginning to incorporate parts of the MISPC into their products. This is the start of the
development of secure, interoperable PKI implementations that will provide security services for confidentiality and
digital signatures and enable secure electronic business transactions. Under a second CRADA with 16 industry partners,
we are expanding the MISPC to incorporate support for confidentiality components. In addition, we are defining
technical security requirements for PKI components. 

 Key Recovery 

 NIST is exploring the use of key recovery technology through a broad agency announcement for several agency pilot
projects and with the help of a technical advisory committee. An announcement in the Commerce Business Daily last
year solicited proposals for products and services that will demonstrate the viability of an infrastructure for key recovery.
NIST has participated in a Key Recovery Demonstration Project involving several government agencies to demonstrate
techniques to recover keys used in data encryption and to identify, test, and evaluate different key recovery products and
services. Planned laboratory work includes development of conformance tests and techniques for integrating key
recovery components into larger functional systems. 

 This effort supports the Administration's policies on privacy, commerce, security, and public safety in the Global
Information Infrastructure. Concerned about potential harm to law enforcement and national security from the use of
unrecoverable encryption, the Administration backs the development of a key management infrastructure to protect U.S.
national security, foreign policy, and law enforcement interests. A technical advisory committee to develop a FIPS for the
federal key management infrastructure has been established to provide industry advice on encryption key recovery
techniques for use by federal government agencies. The Committee currently includes 20 industry members. The
Committee has developed a draft key recovery model and specifications for the security and functionality of key recovery
components. The draft specifications are available to industry organizations that wish to develop products that meet
customer requirements for key recovery. The specifications are available for review at the Web site listed at the end of
this bulletin. 

 Export Controls on Cryptography 

 The Administration has announced changes to the export control rules for encryption items on the U.S. Munitions List.
Except for those items specifically designed, developed, configured, adapted, or modified for military applications,
control of the export of encryption items has been transferred to the Department of Commerce. One of the options
allowed under the revised rules is the export and re-export of non-recoverable encryption items up to 56-bit key length
DES or equivalent strength after a one-time review of the strength of the item and if the exporter makes satisfactory
commitments to build and/or market recoverable encryption items, to support an international key management
infrastructure. This policy applies to hardware and software and will last through December 31, 1998. Many U.S.
vendors are planning key recovery products as part of the licensing provisions under the Department of Commerce's
export control regulations. 

 The Department of Commerce continues to review the export control policies and recently announced that it had
completed guidelines to allow the export of U.S.-manufactured encryption products of any bit-length when used by
banks, financial institutions, and their branches around the world to secure private electronic transactions. The new
guidelines will allow for the export of strong encryption products, with or without recovery features, to eligible
institutions without a license, after a one-time review. Eligible institutions include banks, security firms, brokers, and
credit card companies in 45 countries. The 45 eligible countries are either members of the international anti-money
laundering accord, the Financial Action Task Force, or have enacted anti-money laundering laws. 

 Summary 

 As the use of information technology expands rapidly, the need for advanced cryptography and high-quality security
techniques and services increases. NIST is working with government and industry organizations to make cryptography
and security services available for all to use in exploiting fully the benefits of the Internet.