Announcing Request for Candidate Algorithm Nominations for the Advanced Encryption Standard

DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

[Docket No. 970725180-7180-01]

RIN No. 0693-ZA16

Announcing Request for Candidate Algorithm Nominations for the

Advanced Encryption Standard

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

Commerce.

ACTION: Notice; Request for candidate encryption algorithm nomination

packages.

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SUMMARY: A process to develop a Federal Information Processing Standard

(FIPS) for Advanced Encryption Standard (AES) specifying an Advanced

Encryption Algorithm (AEA) has been initiated by the National Institute

of Standards and Technology (NIST). This notice requests submission of

candidate algorithms for consideration for inclusion in the AES and

specifies how to submit a nomination package. The requirements for

candidate algorithm submission packages and minimum acceptability

requirements that must be satisfied in order to be deemed a ``complete

and proper'' submission are presented. the evaluation criteria which

will be used to appraise the candidate algorithms are also described.

It is intended that the AES will specify an unclassified, publicly

disclosed encryption algorithm available royalty-free worldwide that is

capable of protecting sensitive government information well into the

next century.

The purpose of this notice is to solicit candidate algorithms from

the public, academic/research communities, manufacturers, voluntary

standards organizations, and Federal, state, and local government

organizations. Following the close of the submission period, NIST

intends to make all submissions publicly available for review and

comment.

DATES: Submission deadline: Candidate algorithm nomination packages

must be received by June 15, 1998.

Submission packages received before April 15, 1998, will be

reviewed for completeness by NIST and notified of their specific

deficiencies, if any, by May 15, 1998, allowing time for deficient

packages to be amended by the submission deadline.

No amendments to deficient packages will be permitted after the

submission deadline. Requests for withdrawal of candidate algorithm

submission packages previously submitted will only be honored until the

submission deadline.

ADDRESSES: Candidate algorithm submission packages should be send to

Director, Information Technology Laboratory, Attn: Advanced Encryption

Standard Nominations, Technology Building, Room A231, National

Institute of Standards and Technology, Gaithersburg, MD 20899.

FOR FURTHER INFORMATION CONTACT:

For general information, contact: Edward Roback, National Institute of

Standards and Technology, Building 820, Room 426, Gaithersburg, MD

20899; telephone 301-975-3696 or via fax at 301-948-1233.

If necessary, general questions for clarification of these

requirements for candidate algorithm submission packages, minimum

acceptability requirements, or evaluation criteria/process should be

sent electronically to [email protected] or via fax to 301-948-1233

(Attn: AES Questions). In fairness to all parties, answers to germane

questions will be made publicly available simultaneously to all those

interested at http://csrc.nist.gov/encryption/aes>. Non-pertinent

questions may be ignored.

Technical questions and questions related to a specific submission

package may be made by contacting either Miles Smid at (301) 975-2938,

or Jim Foti at (301) 975-5237.

NIST will endeavor to answer all questions in a timely manner.

SUPPLEMENTARY INFORMATION: This section contains the following:

1. Background

2. Requirements for Candidate Algorithm Submission Packages

2.A Cover sheet

2.B Algorithm Specifications and Supporting Documentation

2.C Magnetic media

2.D Intellectual property statements/agreements/disclosures

2.E General Submission Requirements

3. Minimum Acceptability Requirements

4. Evaluation Criteria

5. First AES Conference

6. Plans for Candidate Evaluation Process

6.A Overview

6.B Round 1 Technical Evaluation

6.C Round 2 Technical Evaluation

7. Miscellaneous

1. Background

This work effort is being initiated pursuant to NIST's

responsibilities under the Computer Security Act of 1987, the

Information Technology Management Reform Act of 1996, Executive Order

13011, and OMB Circular A-130.

NIST recognizes that many institutions, both within and outside the

Federal Government, have considerable investments in their current

installed base of encryption equipment implementing the Data Encryption

Algorithm, specified in the Data Encryption Standard (DES, Federal

Information Processing Standard 46-2). DES was first approved in 1977

and was most recently reaffirmed by the Secretary in 1993, until

December 1998. In 1993 the following statement was included in the

standard:

At the next review (1998), the algorithm specified in this

standard will be over twenty years old. NIST will consider

alternatives which offer a high level of security. One of these

alternatives may be proposed as a replacement standard at the 1998

review.

It is NIST's view that a multi-year transition period will be

necessary to move toward any new encryption standard and the DES will

continue to be of sufficient strength for many applications. NIST will

consult with all interested parties so that a smooth transition can be

accomplished. NIST may not complete the AES selection process before

the end of its 1998 DES Review, and an interim solution(s) may be

necessary.

For interoperability and other purposes, NIST strongly desires to

select a single block encryption algorithm to be specified in the AES

with a strength equal to or better than that of Triple DES and

significantly improved efficiency. However, if more than one suitable

candidate is identified which provides significantly better advantages

in a specific application(s), NIST may consider recommending more than

one algorithm. Present resource constraints do not permit the

development of a specific standard algorithm for 8-bit smart card

implementations or a standard stream cipher. It is hoped that the block

cipher selected will be suitably flexible for a wide variety of

implementations, recognizing that it may not operate with optimal

efficiency in each and every potential application.

2. Requirements for Candidate Algorithm Submission Packages

To be considered as a ``complete'' nomination package (and continue

further in the AES consideration process), candidate algorithm

submission packages MUST contain the following (as described in detail

below):

Cover sheet

Algorithm Specifications and Supporting Documentation

Magnetic media

Intellectual property statements/agreements/disclosures

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Each of these is discussed in detail below, including ``general

submission requirements'' which all nominations must also satisfy.

2. A Cover sheet

A cover sheet containing the following information:

Name of submitted algorithm

Principal submitter's name, telephone, fax, organization, postal

address, e-mail address

Name(s) of auxiliary submitter(s)

Name of algorithm inventor(s) developer(s)

Name of owner, if any, of the algorithm. (normally expected to be the

same as the submitter)

Signature of Submitter (optional) Backup point of contact (w/telephone,

fax, postal address, e-mail)

2.B Algorithm Specifications and Supporting Documentation

2.B.1 A complete written specification of the algorithm shall be

included, consisting of all necessary mathematical equations, tables,

diagrams, and parameters that are needed to implement the algorithm.

The submission of all design rationale (e.g., method for generating

table values, rationale for number of rounds, etc.) is strongly

encouraged, in order to facilitate the public evaluation process.

Parity bits shall not be specified in the key definition. The bit

naming/numbering convention for the key shall be provided by the

submitter.

2.B.2 A statement of the algorithm's estimated computational

efficiency in hardware and software shall be included. At a minimum,

the submitter shall state efficiency estimates for the ``NIST AES

analysis platform'' (specified elsewhere in section 6.B) and for 8-bit

processors. (Efficiency estimates for other platforms may be included

at the submitters' discretion.) These estimates shall each include the

following information, at a minimum:

a. Description of the platform used to generate the estimate, in

sufficient detail so that the estimates could be verified in the public

evaluation process (e.g., for software running on a PC, include

processor, clock speed, memory, operating system, etc.). For hardware

estimates, it is encouraged that a gate count (or estimated gate count)

be included.

b. Speed estimate for the algorithm on the platform specified in

section 6.B. At a minimum, the number of clock cycles required to

(1) encrypt one block of data,

(2) decrypt one block of data,

(3) setup a key,

(4) setup the algorithm (e.g., build internal tables), and

(5) change a key after its initial setup

shall be specified for each key- and block-size combination required in

the Minimum Acceptability Requirements section of this announcement.

c. Any available information on tradeoffs between speed and memory.

2.B.3 A series of Known Answer Tests (KATs) and Monte Carlo Tests

(MCTs) shall be included as specified below. All of these KAT and MCT

values shall be submitted electronically, in separate files, on a

diskette as described in section 2.C.3. (The files containing test

values may be compressed using PKZIP or GNUZIP to conserve disk space.)

Each file shall be clearly labeled with header information listing: (1)

Algorithm name, (2) Test name, (3) Description of the test, and (4)

Key-block size combination being tested. All values within the file

shall be clearly labeled (e.g., index, key, plaintext, ciphertext,

etc.), and shall be in the exact format specified by NIST on its WWW

site at http://csrc.nist.gov/encryption/aes>.

a. All applicable KATs shall be included that can be used to

exercise various features of the algorithm when operated in the

Electronic Codebook (ECB) mode. A set of KATs shall be included for

each key and block size specified in the Minimum Acceptability

Requirements section. Required KATs include:

i. Variable Key Known Answer Test--A variable key KAT is required

for the algorithm's encryption state. For an n-bit key size, there

shall be n key-plaintext-ciphertext triples. The plaintext shall always

consist entirely of binary zeros; the key shall always contain a single

`1' bit and n-1 `0' bits, and the n possible keys (where each key has

the `1' bit in a different position) shall be used to generate

ciphertext. (To run this test for decryption, the ciphertext should be

used as input to recover the block of all zero bits, for each possible

one-bit key.)

ii. Variable Plaintext Known Answer Test--A variable plaintext KAT

is required for the algorithm's encryption state. For an m-bit block

size, there shall be m kep-plaintext-ciphertext triples. The key shall

always consist entirely of binary zeros; the plaintext block shall

always contain a single `1' bit and m-1 `0' bits, and the m possible

blocks (where each input block has the `1' bit in a different position)

shall be used to generate ciphertext. (To run this test for decryption,

the ciphertext should be used as input to recover the correct input

block, using the key consisting only of `0' bits.)

iii. If the candidate algorithm calculates intermediate values

(e.g., internal rounds) for an encryption or decryption operation, then

the submitter shall include known answers for those intermediate values

for a single encryption and decryption operation for each of the

required key- and block-size combinations.

iv. If tables are used in the algorithm, then a known answer test

shall be included to exercise every table entry.

Note: The submitter may include any other known answer tests

that exercise different features of the algorithm (e.g., for

permutation tables, etc.). The purposes of these tests shall be

clearly described in the file containing the test values.

b. Four Monte Carlo Tests shall be included, with key and data

values, for each of the key-block combinations required in the Minimum

Acceptability Requirements section. These four tests correspond with

tests specified in the NIST Special Publication, Modes of Operation

Validation System: Requirements and Procedures [MOVS]. The four tests

required for the AES submissions correspond with the two Electronic

Codebook Modes Tests for encryption and decryption (Sections 5.1.1.5

and 5.1.2.5 in [MOVS]) the two Cipher Block Chaining Modes Tests for

encryption and decryption (Sections 5.2.1.5 and 5.2.2.5 in [MOVS]).

A link to a description of the required tests will be available at

http://csrc.nist.gov/encryption/aes>. Required submission data for the

Monte Carlo Tests will also be found at that location.

2.B.4 A statement of the expected strength (i.e. workfactor) of

the algorithm shall be included, along with any supporting rationale.

The expected strength shall be given for each key- and block-size

combination required in the minimum Acceptability Requirements section

of this announcement, and for all other key- and block-size

combinations claimed to be supported by the algorithm.

2.B.5 An analysis of the algorithm with respect to known attacks

(e.g., known and chosen plaintext) shall be included. In addition, all

known weak keys, equivalent keys, complementation properties,

restrictions on key selection, and other similar features of the

algorithm shall be noted by the submitter. If no such values are known,

then this shall be stated by the submitter.

The submitter should provide any mathematical rationale for the

non-existence of ``trap-doors'' in the algorithm, to the greatest

extent possible.

The submitter shall provide a list of known references to any

published

[[Page 48053]]

materials describing or analyzing the security of the submitted

algorithm. Submission of copies of these materials (accompanied by a

waiver of copyright or permission from the copyright holder for AES

public evaluation purposes) is encouraged.

2.B.6 A statement shall be included that lists and describes

advantages and limitations of the algorithm. Such advantages and

limitations shall address the ability to:

a. implement the algorithm as a stream cipher, Message

Authentication Code (MAC) generator, pseudo-random number generator,

hashing algorithm, etc.

b. implement the algorithm in various environments, including--but

not limited to: 8-bit processors (smartcards), ATM, HDTV, B-ISDN, voice

applications, satellite applications, etc. To demonstrate the

efficiency of a hardware implementation of the algorithm, the submitter

may include a specification of the algorithm in a nonproprietary

Hardware Description Language (HDL).

c. use the algorithm with key- and block-sizes other than those

required as a minimum in the Minimum Acceptability Requirements section

of this announcement.

If the submitter believes that the algorithm has certain features

deemed advantageous by the submitter, then these should be listed and

described, along with supporting rationale. Some examples of these

features might include, for example: throw-away tables, mathematically

(rather than empirically) designed tables, statistical basis for inter-

round mixing, variable key setup time, etc.

2.C Magnetic Media

2.C.1 Reference Implementation

A reference implementation shall be submitted, in order to promote

the understanding of how the candidate algorithm may be implemented.

This implementation shall consist of source code written in ANSI C;

appropriate comments should be included in the code, and it should

clearly map to the algorithm description included under section 2.B.1.

Since this implementation is intended for reference purposes, clarity

in programming is more important than efficiency.

The reference implementation shall be capable of fully

demonstrating the operation of the candidate algorithm. The reference

implementation shall support all key- and block-size combinations

specified in the Minimum Acceptability Requirements section of this

announcement. Additionally, it must support all other key-block sizes

that are claimed to be supported by the algorithm.

NIST will specify a cryptographic API for the ANSI C

implementations, which will be made available at http://csrc.nist.gov/

encryption/aes>. All ANSI C submissions shall implement that API, so

that the NIST test system can be compatible with all submissions.

Separate source code for implementing the required Known Answer

Tests and Modes Tests with the reference implementation shall also be

included. This code shall be able to process input specified in the

format indicated by NIST (on the WWW site as referred to under section

2.B.3) and run the required tests.

The reference implementation shall be provided on a single

diskette, which shall be labeled with the submitter's name, the

algorithm name, and ``Reference Implementation.''

2.C.2 Mathematically Optimized Implementation

Two mathematically optimized implementations of the candidate

algorithm shall be submitted, so that NIST can perform tests in two

different languages in order to demonstrate the potential for efficient

implementation. These two implementations shall be specified in ANSI C

and Java programming languages:

i. ANSI C: The first mathematically optimized implementation shall

be specified in ANSI C source code. NIST intends to use the ANSI C

compiler specified under ``Round 1 Technical Analysis'' to compile the

code and link it to the NIST test system. (NIST received many comments

that the optimized implementation should be written in C, since it is a

very common language.)

NIST will specify a cryptographic API for the ANSI C

implementations, which will be made available at http://csrc.nist.gov/

encryption/aes>. All ANSI C submissions shall implement that API, so

that the NIST test system can be compatible with all submissions.

ii. Java language specification: The second mathematically

optimized implementation shall be specified in the Java programming

language, as defined by the Java Development Kit (JDK) version 1.1.

This JDK 1.1 is publicly available for multiple platforms from

Javasoft, at http://www.javasoft.com>. NIST has selected Java as one

language for the mathematically optimized implementations because it

will provide an accurate relative mathematical efficiency measure of

the different candidate algorithms, since it uses machine-independent

code. The use of one Java Virtual Machine--to test all of the Java

implementations submitted to NIST--is intended to eliminate differences

in hardware optimizations that may occur when using other languages. It

is not intended that the Java implementation will provide an absolute

efficiency measure of each candidate algorithm on the NIST Analysis

Platform.

Submissions are required to use the cryptographic API defined by

the Java Cryptography Architecture (JCA) in conjunction with the Java

Cryptography Extension (JCE). An AES submitter shall create a

Cryptography Package Provider (CPP) that implements the submitted

candidate algorithm. The Provider class is described in the JCA (Refer

to http://java.sun.com:80/products/jdk/1.1/docs/guide/security/

CryptoSpec.html>, under ``The Provider Class''; JCE 1.1 APIs may be

found at http://java.sun.com/security>). The ``Cipher'' engine

subclass within the CPP (as defined in the JCE) shall then be used to

implement the candidate encryption algorithm. Other appropriate engine

subclasses from the JCA and JCE may also be implemented, to accommodate

features of the particular candidate algorithm (e.g., ``Key Generator''

class in the JCE).

General Requirements for Both Mathematically Optimized Implementations

Both of the mathematically optimized implementations shall support

key- and block-size combinations specified in the Minimum Acceptability

Requirements section of this announcement.

The mathematically optimized implementations shall operate in the

Electronic Codebook (ECB), Cipher Block Chaining (CBC), and 1-bit

Cipher Feedback (1-CFB) modes for encryption and decryption. Other

modes are not required to be implemented in the software provided to

NIST.

Separate source code for implementing the required Known Answer

Tests and Modes Tests with the mathematically optimized implementations

shall also be included. This code shall be able to process input

specified in the format indicated by NIST (on the WWW site as referred

to under section 2.B.3) and run the required tests.

The submitter shall provide the mathematically optimized

implementations on two separate diskettes, which shall be labeled with

the submitter's name, the algorithm name, and ``Optimized--ANSI C'' or

``Optimized--Java''.

Additionally, submitters may, at their discretion, submit revised

optimized

[[Page 48054]]

implementations (for both the ANSI C and Java implementations) for use

in the Round 2 evaluation process, allowing additional time for

improvements. These must be received prior to the beginning of the

round 2 evaluation; submittors will be notified of the specific

deadline as appropriate. Note that the mathematically optimized

implementations on file with NIST at the close of the initial

submission period will be the ones used in the Round 1 evaluation.

2.C.3 Test Values--Known Answer Tests and Monte Carlo Tests

The files on this diskette shall contain all of the test values

required under section 2.B.3 of this announcement. That section

includes descriptions of the required tests as well as a list of the

values that must be provided. These files may be compressed using PKZIP

or GNUZIP to conserve disk space, if necessary.

The required format for the test vectors will be specified by NIST

at http://csrc.nist.gov/encryption/aes>

The test values shall be provided on a single diskette, which shall

be labeled with the submitter's name, the algorithm name, and ``Test

Values: Known Answer Tests and Monte Carlo Tests.''

2.C.4 Supporting Documentation

So as to facilitate electronic distribution of submissions to all

interested parties, copies of all written materials must also be

submitted in electronic form in either PostScript or Adobe PDF. PDF is

preferable. (NIST will convert PostScript submissions to PDF.)

Submitters planning to create PDF are encouraged to use the thumbnail

and bookmark features, to have a clickable table of contents (if

applicable), and to include other links within the PDF as appropriate.

To create a PostScript file, users of PC word processors should

configure their software to print using a PostScript printer driver,

and capture the output using the ``print to file'' feature, preferably

using standard PostScript printer fonts (not downloaded fonts).

Users of TeX, LaTeX/DVIPS should use PostScript Type 1 fonts,

preferably standard PostScript printer fonts, rather than the default

embedded bitmapped Computer Modern fonts. Instructions for configuring

DVIPS can be found at http://www.adobe.com/supportservice/custsupport/

SOLUTIONS/385e.htm>, ``Creating quality Adobe PDF files from TeX with

DVIPS,'' by Kendall Whitehouse/EMERGE, FaxYI number 131303. (This is

cited for reference purposes only, and does not constitute a direct or

implied endorsement.)

NIST then intends to make submissions available electronically

(consistent with U.S. export regulations) in both PostScript and PDF

formats.

This electronic version of the supporting documentation shall be

provided on diskette(s), which shall be labeled with the submitter's

name, the algorithm name, and ``Supporting Documentation.'' If multiple

diskettes are necessary, each diskette must also be labeled with ``#m

of n'' as appropriate.

2.C.5 General Requirements for Magnetic Media

A separate diskette shall be used for the reference implementation,

mathematically optimized implementations, test values, and supporting

materials.

All magnetic media presented to NIST shall be free of viruses or

other malicious code. Media submitted will be scanned for the presence

of such code. If such malicious code is found, NIST will notify the

submitter and ask that a clean version of the magnetic media be re-

submitted.

All magnetic media shall be submitted on 3.5'' 1.44MB floppy

diskettes, formatted for use on an IBM-compatible PC.

A file labeled ``README'' shall be included on each diskette,

listing all files included on the diskette, with a brief description of

each.

NIST is in the process of defining a selected set of cryptographic

service calls for the ANSI C implementations. For the Java

implementation, NIST will use calls from the Java Cryptography

Architecture API. These two sets of calls shall be used by the NIST

test software to make appropriate calls to the optimized and reference

implementations, so that the test software does not have to be

rewritten for each submitted algorithm. Therefore, both the

mathematically optimized and reference implementations are required to

conform with these specific calls. The implementations shall be

supplied in source code so that NIST can compile and link them

appropriately with the test software. The two selected sets of required

calls will be available at the following location: http://

csrc.nist.gov/encryption/aes>. NIST intends that these will be

available within three months after publication of this notice.

2.D Intellectual Property Statements/Agreements/Disclosures

After review of the public comments on the draft minimum

acceptability requirements and evaluation criteria (published for

comment in the Federal Register on January 2, 1997), NIST has

determined that potential users of the AES desire to have the AES

available worldwide on a royalty free basis. Additionally, based upon

the results of the April 15, 1997 public workshop held on the draft

evaluation criteria and submission requirements, NIST believes there is

a reasonable basis to expect a sufficient number and variety of

submissions willing to meet these licensing conditions such that the

expressed needs of potential AES users can be accommodated.

In order to ensure this and minimize any intellectual property

issues, the following statement is required:

2.D.1 Statement by the Submitter

I, ________ (print submitter's full name) ________ do hereby

declare that to the best of my knowledge the practice of the algorithm,

reference implementation, and mathematically optimized implementations,

I have submitted, known as ________ (print name of algorithm) ________

may be covered by the following U.S. and/or foreign patents: ________

(describe and enumerate or state ``none'' if appropriate) ________.

I do herby declare that I am aware of no patent applications which

may cover the practice of my submitted algorithm, reference

implementation or mathematically optimized implementations. -OR- I do

hereby declare that the following pending patent applications may cover

the practice of my submitted algorithm, reference implementation or

mathematically optimized implementations: ________ (describe and

enumerate) ________.

I do hereby understand that my submitted algorithm may not be

selected for inclusion in the Advanced Encryption Standard. I also

understand and agree that after the close of the submission period, my

submission may not be withdrawn from public consideration for inclusion

in the Federal Information Processing Standard (FIPS) for Advanced

Encryption Standard (AES). I further understand that I will not receive

financial compensation from the government for my submission. I certify

that, to the best of my knowledge, I have fully disclosed all patents

and patent applications relating to my algorithm. I also understand

that the U.S. Government may, during the course of the lifetime of the

AES or during the FIPS public review process, modify the algorithm's

specifications (e.g., to protect against a newly discovered

vulnerability). Should my submission be

[[Page 48055]]

selected for inclusion in the AES, I hereby agree not to place any

restrictions on the use of the algorithm intending it to be available

on a worldwide, non-exclusive, royalty-free basis.

I do hereby agree to provide the statements required by sections

2.D.2 and 2.D.3, below, for any patent or patent application identified

to cover practice of my algorithm, reference implementation or

mathematically optimized implementations and the right to use such

implementation for the purposes of the AES evaluation process.

I understand that NIST will announce the selected algorithm(s) and

proceed to publish the draft FIPS for public comment. If my algorithm

(or the derived algorithm) is not selected for inclusion in the FIPS

(including those not selected for second round of public evaluation), I

understand that all rights, including use rights of the reference and

mathematically optimized implementation, revert back to the submitter

(and other owner[s] as appropriate). Additionally, should the U.S.

Government not select my algorithm for inclusion in the AES after a

period of four years from the close of the submission date for

candidate algorithms, all rights revert to the submitter (and other

owner[s] as appropriate).

Signed:

Title:

Dated:

Place:

2.D.2 Statement by Patent (and Patent Application) Owner(s)

If there are any patents (or patent applications) identified by the

submitter, including those held by the submitter, the following

statement must be signed by each and every owner of the patent and

patent applications above identified.

I, ________ (print full name) ________, of ________ (print full

postal address) ________, am the owner or authorized representative of

the owner (print full name, ________ if different than ________ the

signer) of the following patent(s) and or ________ patent

application(s): ________ (enumerate) ________, and do hereby agree to

grant to ________ any interested party if the algorithm known as

________ (print name of algorithm ________, is selected for inclusion

in the Advanced Encryption Standard, an irrevocable nonexclusive

royalty-free license to practice the referenced algorithm, reference

implementation or the mathematically optimized implementations.

Furthermore, I agree to grant the same rights in any other patent

granted to me or my company which may be necessary for the practice of

the referenced algorithm, reference implementation, or the

mathematically optimized implementations.

Signed:

Title:

Dated:

Place:

Note that the government may conduct research as may be appropriate

to verify the availability of the submission of a royalty free basis

worldwide.

2.D.3 Statement by Reference/Mathematically Optimized Implementations'

Owner(s)

The following must also be included:

I, ________ (print full name) ________, am the owner of the

submitted reference implementation and mathematically optimized

implementations and hereby grant the Government and any interested

party the right to use such implementations for the purposes of the AES

evaluation process notwithstanding that the implementations may be

copyrighted.

Signed:

Title:

Dated:

Place:

2.E General Submission Requirements

NIST welcomes both domestic and international submissions; however,

in order to facilitate analysis and evaluation, it is required that the

submission packages be in English. This information includes the cover

sheet, algorithm specification and supporting documentation, source

code, and intellectual property information. Any required information

that is submitted in a language other than English shall render the

submission package ``incomplete.'' Optional supporting materials (e.g.,

journal articles) in another language may be submitted.

Classified and/or proprietary submissions shall not be accepted.

3. Minimum Acceptability Requirements

Those packages which are deemed to be ``complete'' will then be

evaluated to see if they contain a ``proper'' candidate algorithm. To

be considered as a ``proper'' candidate algorithm submissions (and

continue further in the AES Development Process), candidate algorithms

must meet the following minimum acceptability requirements:

1. The algorithm must implement symmetric (secret) key

cryptography.

2. The algorithm must be a block cipher.

3. The candidate algorithm shall be capable of supporting key-block

combinations with sizes of 128-128, 192-128, and 256-128 bits. A

submitted algorithm may support other key-block sizes and combinations,

and such features will be taken into consideration during analysis and

evaluation.

(End of minimum acceptability requirements)

Candidate algorithm submission packages which are complete (as

defined earlier) and whose algorithm meets the minimum acceptability

requirements (as defined immediately above) will be deemed to be

``complete and proper'' submissions. Those deemed otherwise will

receive no further consideration. A complete list of submissions will

be publicly announced by NIST--those which are ``complete and proper,''

and any others.

4. Evaluation Criteria

In order to provide a basis for the analysis and evaluation of

encryption algorithms submitted to be considered for incorporation into

the FIPS for AES, evaluation criteria will be used to review candidate

algorithms. All of NIST's analysis results will be made publicly

available.

Although NIST will be performing its own analyses of the candidate

algorithms, NIST strongly encourages public evaluation, making those

results publicly available and submitting them to NIST. This

information may be addressed at the Second and Third AES Candidate

Conferences. NIST will take into account its own analysis, as well as

all other input received, in order to make its decision regarding the

AES selection.

Security (i.e., the effort required to cryptanalyze)

The security provided by an algorithm is the most important factor

in the evaluation.

Algorithms will be judged on the following factors:

i. Actual security of the algorithm compared to other submitted

algorithms (at the same key and block size).

ii. The extent to which the algorithm output is indistinguishable

from a random permutation on the input block.

iii. soundness of the mathematical basis for the algorithm's

security.

iv. Other security factors raised by the public during the

evaluation process, including any attacks which demonstrate that the

actual security of the algorithm is less than the strength claimed by

the submitter.

[[Page 48056]]

Claimed attacks will be evaluated for practicality.

Cost

i. Licensing requirements: NIST intends that when the AES is

issued, the algorithm(s) specified in the AES shall be available on a

worldwide, non-exclusive, royalty-free basis.

ii. Computational efficiency: The evaluation of computational

efficiency will be applicable to both hardware and software

implementations. Round 1 analysis by NIST will focus primarily on

software implementations and specifically on one key-block size

combination (128-128); more attention will be paid to hardware

implementations and other supported key-block size combinations

(particularly those required in the ``Minimum Acceptability

Requirements'' section) during Round 2 analysis.

Computational efficiency essentially refers to the speed of the

algorithm. NIST's analysis of computational efficiency will be made

using each submission's mathematically optimized implementations on the

platform specified under ``Round 1 Technical Evaluation'' below. Public

comments on each algorithm's efficiency (particularly for various

platforms and applications) will also be taken into consideration by

NIST.

iii. Memory requirements: The memory required to implement a

candidate algorithm--for both hardware and software implementations of

the algorithm--will also be considered during the evaluation process.

Round 1 analysis by NIST will focus primarily on software

implementations; more attention will be paid to hardware

implementations during Round 2.

Memory requirements will include such factors as gate counts for

hardware implementations, and code size and RAM requirements for

software implementations.

Testing will be performed by NIST using the mathematically

optimized implementations provided in the submission package. Memory

requirement estimates (for different platforms and environments) that

are included in the submission package will also be taken into

consideration by NIST. Input from public evaluations of each

algorithm's memory requirements (particularly for various platforms and

applications) will also be taken into consideration by NIST.

Algorithm and Implementation Characteristics

i. Flexibility: Candidate algorithms with greater flexibility will

meet the needs of more users than less flexible ones, and therefore,

inter alia, are preferable. However, some extremes of functionality are

of little practical application (e.g., extremely short key lengths)--

for those cases, preference will not be given.

Some examples of ``flexibility'' may include (but are not limited

to) the following:

a. The algorithm can accommodate additional key- and block-sizes

(e.g., 64-bit block sizes, key sizes other than those specified in the

Minimum Acceptability Requirements section, [e.g., keys between 128 and

256 that are multiples of 32 bits, etc.]).

b. The algorithm can be implemented securely and efficiently in a

wide variety of platforms and applications (e.g., 8-bit processors, ATM

networks, voice & satellite communications, HDTV, B-ISDN, etc.).

c. The algorithm can be implemented as a stream cipher, Message

Authentication Code (MAC) generator, pseudo-random number generator,

hashing algorithm, etc.

ii. Hardware and software suitability: A candidate algorithm shall

not be restrictive in the sense that it can only be implemented in

hardware. If one can also implement the algorithm efficiency in

firmware, then this will be an advantage in the area of flexibility.

iii. Simplicity: A candidate algorithm shall be judged according to

relative simplicity of design.

5. Initial Planning for the First AES Candidate Conference

An open public conference is being planned for the summer of 1998,

at which the submitter of each complete and proper nomination package

is invited to publicly discuss and explain their candidate algorithm.

Written portions of all submitted candidates will be made available

at the Conference, including those not deemed ``complete and proper.''

Submitters of complete and proper submissions will be invited to speak

to discuss their submission and answer questions.

As details and registration procedures are finalized, they will be

posted to http://csrc.nist.gov/encryption/>.

6. Plans for Candidate Evaluation Process

This section provides an overview of the envisioned AES candidate

review process, including NIST's plans for technical analysis of

submissions.

6.A Overview

Following the close of the call for candidate algorithm submission

packages, NIST will review them to determine which are ``complete and

proper,'' as described elsewhere in this notice. NIST then intends to

make all submissions publicly available (consistent with U.S. export

regulations) and invite public comments on the ``complete and proper''

submissions. To help better inform the public, the First AES Candidate

Conference will be held at the start of the public comment process to

allow submitters to publicly explain and answer questions regarding

their submissions. NIST intends to publish a separate Federal Register

notice in the future requesting public comments on the candidate

algorithms in the Round 1 evaluation to be used in narrowing of the

candidate pool for more careful study and analysis in Round 2.

During the Round 1 public review, NIST intends to technically

evaluate the candidate algorithm as outlined in the ``Round 1 Technical

Evaluation'' section below. Note that NIST does not intend to conduct

its own cryptanalysis, but, rather it will review the public

evaluations of the candidate algorithms' cryptographic strengths and

weaknesses, and NIST will use these in determining if an algorithm

meets the objectives of the AES. Because of limited resources, and also

to avoid moving evaluation targets (i.e., modifying the submitted

algorithms undergoing public review), NIST will not accept

modifications to the submitted algorithm during Round 1.

For informational and planning purposes, near the end of the Round

1 public evaluation process, NIST intends to hold the Second AES

Candidate Conference (approximately six months after the first

conference; exact date to be scheduled.) Its purpose will be to

publicly discuss the AEA candidate algorithms by NIST and others, and

provide NIST with advice for narrowing the field of algorithms to be

considered for the AEA.

NIST thereafter intends to narrow the field of candidates to no

more than five candidate algorithms based upon its own analysis, public

comment, and all other available information. It is envisioned that

this narrowing will be done primarily on security, efficiency, and

intellectual property considerations.

Before the start of Round 2 evaluation, submitters have the option

of providing updated mathematically optimized implementations for use

during the second phase of evaluation (for those algorithms remaining

in the Round 2 evaluation). During the course of Round 1 evaluations it

is conceivable that some small deficiencies may be identified in even

some of the most promising

[[Page 48057]]

candidates. Therefore, for the Round 2 evaluations, small modifications

to the submitted algorithms will be permitted for their security or

efficiency purposes. Submitters may submit minor changes (no

substantial redesigns) along with a supporting explanation/

justification (see below) which must be received by NIST prior to the

beginning of Round 2. (Submitters will be notified by NIST of the exact

deadline.) If this option is exercised, new reference and

mathematically optimized implementations and written descriptions must

also be provided by the start of Round 2. This will allow public review

of the modified algorithms during the entire course of the second

evaluation.

Note: All proposed changes for Round 2 must be proposed by the

submitter; no proposed changes (to the algorithm or implementations)

will be accepted from a third party.

After the narrowed list of candidate algorithms is officially

announced, NIST intends that a six to nine month public review period

will follow (the Round 2 evaluation). During the public review, NIST

intends to technically evaluate the candidate algorithms as outlined in

the two sections below. Near the end of the public review period, NIST

intends to hold the Third AES Candidate Conference. (The exact date is

to be scheduled.)

NIST then will select the algorithm(s) for inclusion in the AES,

which will be incorporated into a draft FIPS, which NIST intends to

announce in the Federal Register for comment.

Note that this schedule for the AES development is somewhat

tentative, depending in part upon the type, quantity, and quality of

submissions. Specific conference dates and public comment periods will

be announced at appropriate times in the future. Note also that as a

result of comments received on the draft evaluation criteria and

submission requirements, NIST has further extended the length of time

for algorithm submissions and each of the ensuing planned public

comment periods.

6.B Round 1 Technical Evaluation

NIST will invite public comments on all complete and proper

submissions. NIST's Round 1 analysis are intended, at a minimum, to be

performed as follows:

i. Key-Block Size Combinations: Round 1 testing by NIST will be

performed on the 128-bit key and 128-bit block size combination. (The

public, however, is welcome to also focus on other key- and block-size

combinations.) Testing of other key-block sizes may be accomplished if

time and resources permit.

ii. Correctness check: The Known Answer Test and Monte Carlo Test

values included with the submission will be used to test the

correctness of the reference and mathematically optimized

implementations, once they are compiled. (It is more likely that NIST

will perform this check of the reference code--and possibly the

optimized code as well--even before accepting the submission package as

``complete and proper.'')

iii. Efficiency testing: Using the submitted mathematically

optimized implementations, NIST intends to perform various

computational efficiency tests for the 128-128 key-block combination,

including the calculation of the time required to perform:

--Algorithm setup,

--Key setup,

--Key change, and

--Encryption and decryption.

NIST may perform efficiency testing on other platforms.

iv. Other testing: Other features of the candidate algorithms may

be examined by NIST.

Platform and Compilers

The above tests will be performed by NIST with the following tools,

at a minimum. Due to limited resources, NIST has limited its own

efficiency analysis to a single, common platform; however, NIST invites

the public to conduct similar tests and compare results on additional

platforms (e.g., RISC processors, 8-bit processors, Digital Signal

Processors, dedicated CMOS, etc.).

i. NIST Analysis Platform: IBM-compatible PC, with an Intel Pentium

Pro Processor, 200MHz clock speed, 64MB RAM, running Windows95.

ii. Compiler (Note that the selection of these two compilers is for

use by NIST in the Rounds 1 and 2, and does not constitute a direct or

implied endorsement by NIST.):

(a) For the reference implementation, NIST intends to use the ANSI

C compiler in the Borland C++ Development Suite 5.0.

(b) For the mathematically optimized implementations, NIST intends

to use the following compilers:

(1) ANSI C implementation: ANSI C compiler found in the Borland C++

Development Suite 5.0, and

(2) Java implementation: NIST intends to use the bytecode compiler

and virtual machine provided in Javasoft's Java Development Kit (JDK)

1.1.

Note: any changes to the intended platform/compiler will be

noted on http://csrc.nist.gov/encryption/aes>.

6.C Round 2 Technical Evaluation

At the end of the Round 1 Technical evaluation and the Second AES

Candidate Conference, NIST intends to narrow the field of candidate

algorithms to five or fewer, in order to focus the remaining efforts of

both NIST and the public. Once again, NIST intends to perform its own

analysis of the submissions, and make that information publicly

available. NIST's Round 2 analysis will, at a minimum, be performed as

follows. Note: the same platform and compilers from Round 1 will be

used for the Round 2.

i. Key-Block Size Combinations: Round 2 testing by NIST will be

performed on the minimum key-block combinations specified in the

Minimum Acceptability Requirements (beyond the 128-128 key-block

combination that was evaluated in Round 1). Note: If the submitter

chose to submit updated mathematically optimized implementations prior

to the beginning of Round 2, then some of the tests performed in Round

1 for the 128-128 combination may be performed again using the new

mathematically optimized implementations. This will be done to obtain

updated measurements.

ii. Efficiency testing: Using the submitted mathematically

optimized implementations, NIST intends to perform various

computational efficiency tests for the minimum key-block combinations

specified in the Minimum Acceptability Requirements, including the

calculation of the time required to perform:

--Algorithm setup,

--Key setup,

--Key change, and

--Encryption and decryption.

NIST will welcome comments regarding the efficiency of the

candidate algorithms when implemented in hardware. NIST may pursue

having the remaining algorithms specified using a Hardware Description

Language, to compare the estimated hardware efficiency of the candidate

algorithms.

NIST may perform efficiency testing using additional platforms.

Once again, NIST welcomes public input regarding efficiency testing on

additional platforms.

iii. Other testing: Other features of the candidate algorithms may

be examined by NIST. If appropriate, analyses from the Second AES

Candidate Conference and the public evaluation during Round 1 may

warrant the testing of specific features.

[[Page 48058]]

7. Miscellaneous

This section is intended to address some of the questions/comments

raised in the review of the draft evaluation criteria.

When evaluating algorithms, NIST will make every effort to obtain

public input and will encourage review of the candidate algorithms by

outside organizations; however, the final decision as to which

algorithms(s) will be proposed to the Secretary of Commerce for

inclusion in the AES is the responsibility of NIST.

NIST intends to develop a validation program for AES conformance

testing, with the goal of having it operational concurrently with the

effective date of the AES.

NIST does NOT have a fixed timeable for completion of the AES.

NIST is not specifically seeking a stream cipher algorithm, since

any block cipher algorithm can be operated in a stream cipher mode.

NIST does not intend to select a wholly distinct algorithm for each

of the minimum required key-block combinations. It is strongly

recommended that no submission be so constructed.

NIST does not wish to target a specific application or platform for

implementing the AES, as the evaluation of candidate algorithms takes

place. However, one factor that is being taken into consideration for

each candidate algorithm is its flexibility--the ability to implement

the algorithm securely and efficiently in a wide variety of platforms

and applications (see ``Algorithm and Implementation Characteristics''

under ``Evaluation Criteria'' section).

NIST does not intend to select a ``backup'' AES algorithm. Rather,

should the circumstances arise (e.g., discovery of a significant

security flaw) which could not be satisfactorily addressed by modifying

the AES, NIST would likely look to the other AES candidate finalists.

Additionally, if a significant period of time has elapsed since the AES

selection, it would also make sense to examine other algorithms which

may have been developed in the intervening period.

Exportability decisions regarding submissions and, eventually,

products implementing AES will be made by the appropriate government

regulatory authorities. NIST is a non-regulatory agency of the U.S.

Department of Commerce.

NIST does not intend to offer financial incentives (e.g., contests)

for cryptanalysis of AES candidates.

Should no appropriate algorithms be submitted in response to this

call, NIST expressly reserves the right to cease this process and

examine other possible courses of action.

Submitters are strongly encouraged to submit only one algorithm

each (presumably the one in which the submitter has the greatest

confidence). Submission of similar, yet distinct, algorithms may delay

the public evaluation process and may well raise public questions as to

the submitter's level of confidence in his/her candidates.

For conference and resource allocation planning purposes, it would

be appreciated if those planning to submit candidates could notify the

individuals listed in the ``For Further Information'' section as soon

as possible.

Appreciation

NIST extends its appreciation to all submitters and those providing

public comments during the AES development process.

Dated: September 8, 1997.

Elaine Bunten-Mines,

Director, Program Office.

[FR Doc. 97-24214 Filed 9-11-97; 8:45 am]

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