20 January 1999: See Draft FIPS 46-3: http://jya.com/dfips46-3.htm

15 January 1999
Source: http://www.access.gpo.gov/su_docs/aces/aaces002.html

Note: To see the Triple DEA listed at the end of this
document properly formatted:  http://jya.com/tdea.htm

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[Federal Register: January 15, 1999 (Volume 64, Number 10)]
[Notices]
[Page 2625-2628]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15ja99-48]

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DEPARTMENT OF COMMERCE

National Institute of Standards and Technology
[Docket No. 981019262-8262-01]
RIN 0693-ZA27


Announcing Draft Federal Information Processing Standard (FIPS)
46-3, Data Encryption Standard (DES), and Request for Comments

AGENCY: National Institute of Standards and Technology (NIST),
Commerce.

ACTION: Notice: request for comments.

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SUMMARY: The Data Encryption Standard (DES) provides specifications for
the Data Encryption Algorithm and is used by federal agencies (and
others outside the government) for the protection of sensitive
information. This standard, first issued in 1977, is reviewed every
five years. The DES, currently specified in Federal Information
Processing Standard (FIPS) 46-2, is due for review in December 1998.
NIST is proposing to replace FIPS 46-2 with FIPS 46-3 to provide for
the use of Triple DES as specified in the American National Standards
Institute (ANSI) X9.52 standard. Comments are sought from industry,
government agencies, and the public on the draft of FIPS 46-3.

DATES: Comments must be received on or before April 15, 1999.

ADDRESSES: Written comments concerning this standard should be sent to:
Information Technology Laboratory, Attention: Review of Draft FIPS 46-
3, National Institute of Standards and Technology, 100 Bureau Drive
Stop 8970, Gaithersburg, MD 20899-8970. Comments may also be sent via
e-mail to ``desreview@nist.gov''.
    Interested parties may order a copy of FIPS 46-2 from the National
Technical Information Service (NTIS), 5285 Port Royal Road,
Springfield, VA 22161. Telephone (703) 487-1650. Copies of FIPS 46-2
and its proposed replacement (Draft FIPS 46-3) may also be downloaded
from <http://csrc.nist.gov/fips>.
    Ordering information for the ANSI X9.52 (Triple DES) standard is
available from American Bankers Assoc./DC, X9 Customer Service Dept.,
PO Box 79064, Baltimore, MD 21279-0064, telephone 1-800-338-0626.

FOR FURTHER INFORMATION CONTACT: Mr. Miles Smid (301) 975-2938,
National Institute of Standards and Technology, 100 Bureau Drive Stop
8930, Gaithersburg, MD 20899-8930.

SUPPLEMENTARY INFORMATION: Federal Information Processing Standard 46,
Data Encryption Standard, first issued in 1977, specifies the Data
Encryption Algorithm for the cryptographic protection of computer data.
The standard provided that it be reviewed within five (5) years to
assess its adequacy. The first review was completed in 1983, and the
standard was reaffirmed for Federal government use (48 FR 41062). The
second review was completed in 1987, and was again reaffirmed for
Federal government use (52 FR 7006) and re-issued as FIPS 46-1 with
minor editorial updating. The third review was completed in 1993, and
the standard was reaffirmed as FIPS 46-2 for Federal government use (58
FR 69347). In addition to hardware implementations, FIPS 46-2 provided
for software implementations of the DES. We are now proposing to
replace FIPS 46-2 with FIPS 46-3 to also allow for the use of Triple
DES as described in ANSI X9.52.
    When DES was reaffirmed in 1993, NIST stated in the announcement
that NIST would ``consider alternatives which offer a higher level of
security'' at the next review in 1998. After the first exhaustion of a
DES key, NIST advised Federal organizations that DES, properly used,
still provided adequate security for many applications. At the time,
NIST also stated that organizations needing security beyond that
provided by the DES could use Triple DES as specified in ANSI X9.52.
NIST worked with the financial community to develop this standard.
Triple DES is a method for using the DES algorithm in three operations,
developed by the private sector and used in many government and private
sector organizations, particularly in the financial services industry.
These operations have been documented and specified as an American
National Standard (ANSI X9.52) by Accredited Standards Committee X9 for
Financial Services,which develops cryptography and public key
infrastructure standards. The American Bankers Association is the
secretariat for X9. Ordering information for the X.52 standard is
contained in the ADDRESSES section.
    Additionally, knowing that the DES' security life was nearing an
end, NIST has been working with industry and the cryptographic
community to develop an Advanced Encryption Standard (AES) for the 21st
century. On January 2, 1997, NIST announced the initiation of an effort
to develop the AES (62 FR 93). It is intended that the AES will specify
an unclassified, publicly disclosed encryption algorithm capable of
protecting sensitive government information well in the next century.
Unfortunately, since it takes a substantial amount of time to gain
confidence in a new encryption algorithm, the AES is not expected to be
a fully developed FIPS for some time to come. Information on NIST's
multi-year effort to develop the AES can be obtained at <http://
www.nist.gov/aes >.
    Recently claims have been made of a special-purpose hardware based
attack on the DES. In light of this most recent attack, NIST can no
longer support the use of the DES for many applications. As with other
security tools, encryption must balance cost against risk. The recent
brute force exhaustion attack by a ``cracking machine'' costing
$250,000 took 56 hours to crack a single message.

[[Page 2626]]

With this special-purpose technology, the average time of cracking per
message would be twice that, since only a quarter of all keys were
tested. In some cases this kind of attack may not pose an immediate or
significant threat--for example where short-term protection of
perishable information is desired. However, advances in technology are
likely to further reduce the average cracking time. Therefore, NIST
recommends the following:

--For existing systems, develop a prudent transition strategy to move
to Triple DES. This strategy should match the strength of the
protective measures against the associated risk. Critical systems
should receive priority
--When building new systems, use Triple DES to protect sensitive,
unclassified data

    These recommendations are reflected in the proposed draft FIPS 46-3
(see below) by recognizing Triple DES, as described in ANSIX9.52, as a
FIPS approved algorithm. Comments are sought on the proposed draft of
FIPS 46-3.

    Authority: This work effort is being conducted pursuant to
NIST's responsibilities under the Computer Security Act of 1987, the
Information Technology Management Reform Act of 1996, Executive
Order 13011, and Office of Management and Budget (OMB) Circular A-
130 for the development of security standards and guidelines for the
protection of sensitive federal information technology systems.

DRAFT Federal Information Processing Standards Publication 46-3;
1999 (Approval Date) Announcing the Data Encryption Standard

    Federal Information Processing Standards Publications (FIPS PUBS)
are issued by the National Institute of Standards and Technology after
approval by the Secretary of Commerce pursuant to section 5131 of the
Information Technology Management Reform Act of 1996 (Pub. L. 104-106),
and the Computer Security Act of 1987 (Pub. L. 100-235).
    1. Name of Standard. Data Encryption Standard (DES).
    2. Category of Standard. Computer Security, Cryptography.
    3. Explanation. The Data Encryption Standard (DES) specifies two
FIPS approved cryptographic algorithms as required by FIPS 140-1. When
used in conjunction with American National Standards Institute (ANSI)
X9.52 standard, this publication provides a complete description of the
mathematical algorithms for encrypting (enciphering) and decrypting
(deciphering) binary coded information. Encrypting data converts it to
an unintelligible form called cipher. Decrypting cipher converts the
data back to its original form called plaintext. The algorithms
described in this standard specifies both enciphering and deciphering
operations which are based on a binary number called a key.
    A DEA key consists of 64 binary digits (``O''s or ``1''s) of which
56 bits are randomly generated and used directly by the algorithm. The
other 8 bits, which are not used by the algorithm, may be used for
error detection. The 8 error detecting bits are set to make the parity
of each 8-bit byte of the key odd, i.e., there is an odd number of
``1''s in each 8-bit byte \1\. A TDEA key consists of three DEA keys,
which is also referred to as a key bundle. Authorized users of
encrypted computer data must have the key that was used to encipher the
data in order to decrypt it. The encryption algorithms specified in
this standard are commonly known among those using the standard. The
cryptographic security of the data depends on the security provided for
the key used to encipher and decipher the data.
---------------------------------------------------------------------------

    \1\ Sometimes keys are generated in an encrypted form. A random
64-bit number is generated and defined to be the cipher formed by
the encryption of a key using a key encrypting key. In this case the
parity bits of the encrypted key cannot be set until after the key
is decrypted.
---------------------------------------------------------------------------

    Data can be recovered from cipher only by using exactly the same
key used to encipher it. Unauthorized recipients of the cipher who know
the algorithm but do not have the correct key cannot derive the
original data algorithmically. However, it may be feasible to determine
the key by a brute force ``exhaustion attack.'' Also, anyone who does
have the key and the algorithm can easily decipher the cipher and
obtain the original data. A standard algorithm based on a secure key
thus provides a basis for exchanging encrypted computer data by issuing
the key used to encipher it to those authorized to have the data. Data
that is considered sensitive by the responsible authority, data that
has a high value, or data that represents a high value should be
cryptographically protected if it is vulnerable to unauthorized
disclosure or undetected modification during transmission or while in
storage. A risk analysis should be performed under the direction of a
responsible authority to determine potential threats. The costs of
providing cryptographic protection using this standard as well as
alternative methods of providing this protection and their respective
costs should be projected. A responsible authority then should make a
decision, based on these analyses, whether or not to use cryptographic
protection and this standard.
    4. Approving Authority. Secretary of Commerce.
    5. Maintenance Agency. U.S. Department of Commerce, National
Institute of Standards and Technology, Information Technology
Laboratory.
    6. Applicability. This standard may be used by Federal departments
and agencies when the following conditions apply:
    (1) An authorized official or manager responsible for data security
or the security of any computer system decides that cryptographic
protection is required; and
    (2) The data is not classified according to the National Security
Act of 1947, as amended, or the Atomic Energy Act of 1954, as amended.
    Federal agencies or departments which use cryptographic devices for
protecting data classified according to either of these acts can use
those devices for protecting sensitive data in lieu of the standard.
    Other FIPS approved cryptographic algorithms may be used in
addition to, or in lieu of, this standard when implemented in
accordance with FIPS 140-1.
    In addition, this standard may be adopted and used by non-Federal
Government organizations. Such use is encouraged when it provides the
desired security for commercial and private organizations.
    7. Applications. Data encryption (cryptography) is utilized in
various applications and environments. The specific utilization of
encryption and the implementation of the DEA and TDEA will be based on
many factors particular to the computer system and its associated
components. In general, cryptography is used to protect data while it
is being communicated between two points or while it is stored in a
medium vulnerable to physical theft. Communication security provides
protection to data by enciphering it at the transmitting point and
deciphering it at the receiving point. DEA forms the basis for TDEA.
File security provides protection to data by enciphering it when it is
recorded on a storage medium and deciphering it when it is read back
from the storage medium. In the first case, the key must be available
at the transmitter and receiver simultaneously during communication. In
the second case, the key must be maintained and accessible for the
duration of the storage period. FIPS 171 provides approved methods for
managing the keys used by the algorithms specified in this standard.

[[Page 2627]]

Public-key based protocols may also be used (e.g., ANSI X9.42).
    8. Implementations. Cryptographic modules which implement this
standard shall conform to the requirements of FIPS 140-1. The
algorithms specified in this standard may be implemented in software,
firmware, hardware, or any combination thereof. The specific
implementation may depend on several factors such as the application,
the environment, the technology used, etc. Implementations which may
comply with this standard include electronic devices (e.g., VLSI chip
packages), micro-processors using Read Only Memory (ROM), Programmable
Read Only Memory (PROM), or Electronically Erasable Read Only Memory
(EEROM), and mainframe computers using Random Access Memory (RAM). When
an algorithm is implemented in software or firmware, the processor on
which the algorithm runs must be specified as part of the validation
process. Implementations of an algorithm which are tested and validated
by NIST will be considered as complying with the standard. Note that
FIPS 140-1 places additional requirements on cryptographic modules for
Government use. Information about devices that have been validated and
procedures for testing and validating equipment for conformance with
this standard and FIPS 140-1 are available from the National Institute
of Standards and Technology, Information Technology Laboratory,
Gaithersburg, MD 20899.
    9. Export Control. Cryptographic devices and technical data
regarding them are subject to Federal Government export controls and
exports of cryptographic modules implementing this standard and
technical data regarding them must comply with these Federal
regulations and be licensed by the Bureau of Export Administration of
the U.S. Department of Commerce.
    10. Patents. Cryptographic devices implementing this standard may
be covered by U.S. and foreign patents, including patents issued to the
International Business Machines Corporation. However, IBM has granted
nonexclusive, royalty-free licenses under the patents to make, use and
sell apparatus which complies with the standard. The terms, conditions
and scope of the licenses are set out in notices published in the May
13, 1975 and August 31, 1976 issues of the Official Gazette of the
United States Patent and Trademark Office (934 O.G. 452 and 949 O.G.
1717).
    11. Alternative Modes of Using the DEA and TDEA. FIPS PUB 81, DES
Modes of Operation, describes four different modes for using DEA
described in this standard. These four modes are called the Electronic
Codebook (ECB) mode, the Cipher Block Chaining (CBC) mode, the Cipher
Feedback (CFB) mode, and the Output Feedback (OFB) mode. ECB is a
direct application of the DES algorithm to encrypt and decrypt data;
CBC is an enhanced mode of ECB which chains together blocks of cipher
text; CFB uses previously generated cipher text as input to the DES to
generate pseudorandom outputs which are combined with the plaintext to
produce cipher, thereby chaining together the resulting cipher; OFB is
identical to CFB except that the previous output of the DES is used as
input in OFB while the previous cipher is used as input in CFB. OFB
does not chain the cipher.
    The X9.52 standard, ``Triples Data Encryption Algorithm Modes of
Operation'' describes seven different modes for using TDEA described in
this standard. These seven modes are called the TDEA Electronic
Codebook Mode of Operation (TECB) mode, the TDEA Cipher Block Chaining
Mode of Operation (TCBC), the TDEA Cipher Block Chaining Mode of
Operation--Interleaved (TCBC-1). TDEA Cipher Feedback Mode of Operation
(TCFB), the TDEA Cipher Feedback Mode of Operation--Pipelined (TCFB-P),
the TDEA Output Feedback Mode of Operation (TOFB), and the TDEA Output
Feedback Mode of Operation--Interleaved (TOFB-I). The TECB, TCBC, TCFB
and TOBF modes are based upon the ECB, CBC, CFB and OFB modes
respectively obtained by substituting the DEA encryption/decryption
operation with the TDEA encryption/decryption operation.
    12. Implementation of this standard. This standard became effective
July 1977. It was reaffirmed in 1983, 1988, 1993, and 1999 (if
approved). It applies to all Federal agencies, contractors of Federal
agencies, or other organizations that process information (using a
computer or telecommunications system) on behalf of the Federal
Government to accomplish a Federal function. Each Federal agency or
department may issue internal directives for the use of this standard
by their operating units based on their data security requirement
determinations.
    With this modification of the FIPS 46-2 standard:
    (1) Triple DES (i.e., TDEA), as specified in ANSI X9.52 will be
recognized as a FIPS approved algorithm.
    (2) Triple DES will be the FIPS approved symmetric encryption
algorithm of choice.
    (3) Single DES (i.e., DEA) will be permitted for legacy systems
only. New procurements to support legacy systems should, where,
feasible, use Triple DES products running in the single DES
configuration.
    (4) Government organizations with legacy DES systems are encouraged
to transition to Triple DES based on a prudent strategy that matches
the strength of the protective measures against the associated risk.

    Note: It is anticipated that triple DES and the Advanced
Encryption Standard (AES) will coexit as FIPS approved algorithms
allowing for a gradual transition to AES. (The AES is a new
symmetric-based encryption standard under development by NIST. AES
is intended to provide strong cryptographic security for the
protection of sensitive information well into the 21st century.)

    NIST provides technical assistance to Federal agencies in
implementing data encryption through the issuance of standards,
guidelines and through individual reimbursable projects.
    13. Specifications. Federal Information Processing Standard (FIPS)
46-3, Data Encryption Standard (DES) (affixed).
    14. Cross Index.
    a. FIPS PUB 31, Guidelines to ADP Physical Security and Risk
Management.
    b. FIPS PUB 39, Glossary for Computer Systems Security.
    c. FIPS PUB 73, Guidelines for Security of Computer Applications.
    d. FIPS PUB 74, Guidelines for Implementing and Using the NBS Data
Encryption Standard.
    e. FIPS PUB 81, DES Modes of Operation.
    f. FIPS PUB 87, Guidelines for ADP Contingency Planning.
    g. FIPS PUB 112, Password Usage.
    h. FIPS PUB 113, Computer Data Authentication.
    i. FIPS PUB 140-1, Security Requirements for Cryptographic Modules.
    j. FIPS PUB 171, Key Management Using ANSI X9.17.
    k. ANSI X9.42 Agreement of Symmetric Keys on Using Diffie-Hellman
and MQV Algorithms.
    l. ANSI X9.52, Triple Data Encryption Algorithm Modes of Operation.
    15. Qualifications. Both this standard and possible threats
reducing the security provided through the use of this standard will
undergo review by NIST as appropriate, taking into account newly
available technology. In addition, the awareness of any breakthrough in
technology or any mathematical weakness of the algorithm will cause
NIST to revaluate this standard and provide necessary revisions.
    With regard to the use of single DES, exhaustion of the DES (i.e.,
breaking a

[[Page 2628]]

DES encrypted ciphertext by trying all possible keys) has become
increasingly more feasible with technology advances. Following a recent
hardware based DES key exhaustion attack, NIST can no longer support
the use of single DES for many applications. Therefore, Government
agencies with legacy single DES systems are encouraged to transition to
Triple DES. Agencies are advised to implement Triple DES when building
new systems.
    16. Comments. Comments and suggestions regarding this standard and
its use are welcomed and should be addressed to the National Institute
of Standards and Technology, Attn: Director, Information Technology
Laboratory, Gaithersburg, MD 20899.
    17. Waiver Procedure. Under certain exceptional circumstances, the
heads of Federal departments and agencies may approve waivers to
Federal Information Processing Standards (FIPS). The head of such
agency may redelegate such authority only to a senior official
designated pursuant to section 3506(b) of Title 44, United States Code.
Waiver shall be granted only when:
    a. Compliance with standard would adversely affect the
accomplishment of the mission of an operator of a Federal computer
system; or
    b. Compliance with a standard would cause a major adverse financial
impact on the operator which is not offset by Government-wide savings.
    Agency heads may act upon a written waiver request containing the
information detailed above. Agency heads may also act without a written
waiver request when they determine that conditions for meeting the
standard cannot be met. Agency heads may approve waivers only by a
written decision which explains the basis on which the agency head made
the required finding(s). A copy of each decision, with procurement
sensitive or classified portions clearly identified, shall be sent to:
National Institute of Standards and Technology; ATTN: FIPS Waiver
Decisions 100 Bureau Drive, Stop 8970, Gaithersburg, MD 20899-8970.
    In addition, notice of each waiver granted and each delegation of
authority to approve waivers shall be sent promptly to the Committee on
Government Operations of the House of Representatives and the Committee
on Government Affairs of the Senate and shall be published promptly in
the Federal Register.
    When the determination on a waiver applies to the procurement of
equipment and/or services, a notice of the waiver determination must be
published in the Commerce Business Daily as a part of the notice of
solicitation for offers of an acquisition or, if the waiver
determination is made after that notice is published, by amendment to
such notice.
    A copy of the waiver, any supporting documents, the document
approving the waiver an any accompanying documents, with such deletions
as the agency is authorized and decides to make under 5 United States
Code Section 552(b), shall be part of the procurement documentation and
retained by the agency.
    18. Special Information. In accordance with the Qualifications
Section of this standard, review of this standard have been conducted
every 5 years since its adoption in 1977. The standard was reaffirmed
during each of those reviews. This revision to the text of the standard
contains changes which allow software implementations of the algorithm,
permit the use of other FIPS approved cryptographic algorithms, and
designate Triple DES (i.e., TDEA) as a FIPS approved cryptographic
algorithm.
    19. Where to Obtain Copies of the Standard. Copies of this
publication are for sale by the National Technical Information Service,
U.S. Department of Commerce, Springfield, VA 22161. When ordering,
refer to Federal Information Processing Standards Publication 46-3
(FIPSPUB46-3), and identify the title. When microfiche is desired, this
should be specified. Prices are published by NTIS in current catalogs
and other issuances. Payment may be made by check, money order, deposit
account or charged to a credit card accepted by NTIS.

(Note that the technical specifications of the DES encryption
algorithm are not reproduced in this Federal Register Notice. They
are available in FIPS 46-2 and the draft of FIPS 46-3. No technical
changes are being proposed in the DES algorithm itself from the
specifications in FIPS 46-2.)

Triple Data Encryption Algorithm
    Let E<INF>K</INF>(I) and D<INF>K</INF>(I) represent the DEA
encryption and decryption of I using DEA key K respectively. Each TDEA
encryption/decryption operation (as specified in ANSI X9.52) is a
compound operation of DEA encryption and decryption operations. The
following operations are used:
    1. TDEA encryption operation: the transformation of a 64-bit block
I into a 64-bit block ) that is defined as follows:

O=E<INF>K3</INF>(D<INF>K2</INF>(E<INF>K1</INF>(I)))

    2. TDEA decryption operation: the transformation of a 64-bit block
I into a 64-bit block O that is defined as follows:

O = D<INF>K1</INF>(E<INF>K2</INF>(D<INF>K3</INF>(I)))

    The standard species the following keying options for bundle
(K<INF>1</INF>, K<INF>2</INF>, K<INF>3</INF>)
    1. Keying Option 1: K<INF>1</INF>, K<INF>2</INF> and K<INF>3</INF>
are independent keys;
    2. Keying option 2: K<INF>1</INF> and K<INF>2</INF> and independent
keys and K<INF>3</INF> = K<INF>1</INF>;
    3. Keying Option 3: K<INF>1</INF> = K<INF>2</INF> = K<INF>3</INF>.
    A TDEA mode of operation is backward compatible with its single DEA
counterpart if, with compatible keying options for TDEA operation,
    1. An encrypted plaintext computed using a single DEA mode of
operation can be decrypted correctly by a corresponding TDEA mode of
operation; and
    2. An encrypted plaintext computed using a TDEA mode of operation
can be decrypted correctly by a corresponding single DEA mode of
operation.
    When using keying Option 3 (K<INF>1</INF> = K<INF>2</INF> =
K<INF>3</INF>), TECB, TCBC, TCFB, amd TOFB modes are backward
compatible with single DEA modes of operation ECB, CBC, CFB, OFB
respectively.
    The diagram in Appendix 2 illustrates TDEA encryption an TDEA
decrytion.

(Note that the two appendices to FIPS 46-3 are not reproduced in
this Federal Register notice. They are available in the complete
draft of FIPS 46-3.)

    Dated: January 8, 1999.
Robert E. Hebner,
Acting Deputy Director.
[FR Doc. 99-898 Filed 1-14-99; 8:45 am]
BILLING CODE 3510-CN-M
