Common Authentication Technology Next Generation S. Whited
Internet-Draft 24 April 2026
Intended status: Best Current Practice
Expires: 26 October 2026
Best practices for password hashing and storage
draft-ietf-kitten-password-storage-10
Abstract
This document outlines best practices for handling user passwords and
other authenticator secrets in client-server systems making use of
SASL.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 26 October 2026.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Whited Expires 26 October 2026 [Page 1]
Internet-Draft Password Storage April 2026
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Terminology . . . . . . . . . . . . . . . 2
2. SASL Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 3
3. Client Best Practices . . . . . . . . . . . . . . . . . . . . 3
3.1. Mechanism Pinning . . . . . . . . . . . . . . . . . . . . 4
3.2. Storage . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Server Best Practices . . . . . . . . . . . . . . . . . . . . 5
4.1. Additional SASL Requirements . . . . . . . . . . . . . . 5
4.2. Storage . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Authentication and Rotation . . . . . . . . . . . . . . . 6
5. KDF Recommendations . . . . . . . . . . . . . . . . . . . . . 6
5.1. Argon2 . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. PBKDF2 . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Scrypt . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.4. Bcrypt . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. Internationalization Considerations . . . . . . . . . . . . . 9
7. Password Complexity Requirements . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Normative References . . . . . . . . . . . . . . . . . . . . 11
11. Informative References . . . . . . . . . . . . . . . . . . . 12
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Following best practices when hashing and storing passwords for use
with SASL impacts a great deal more than just a user's identity. It
also affects usability, backwards compatibility, and interoperability
by determining what authentication and authorization mechanisms can
be used.
1.1. Conventions and Terminology
Various security-related terms are to be understood in the sense
defined in [RFC4949]. Some may also be defined in
[DOI_10.6028_NIST.SP.800-63-4] Appendix B,
[DOI_10.6028_NIST.SP.800-63B-4] Appendix D, and in [NIST_SP_800_132]
section 3.1.
Throughout this document the term "password" is used to mean any
password, passphrase, PIN, or other memorized secret.
Other common terms used throughout this document include:
Mechanism pinning A security mechanism which allows SASL clients to
Whited Expires 26 October 2026 [Page 2]
Internet-Draft Password Storage April 2026
resist downgrade attacks. Clients that implement mechanism
pinning remember the perceived strength of the SASL mechanism used
in a previous successful authentication attempt and thereafter
only authenticate using mechanisms of equal or higher perceived
strength.
Pepper A secret added to a password hash like a salt. Unlike a
salt, peppers are secret and the same pepper may be reused for
many hashed passwords.
Salt In this document salt is used as defined in [RFC4949].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. SASL Mechanisms
For clients and servers that support password based authentication
using SASL [RFC4422] it is RECOMMENDED that the following mechanisms
be implemented:
* SCRAM-SHA-256 [RFC7677]
* SCRAM-SHA-256-PLUS [RFC7677]
System entities SHOULD NOT invent their own mechanisms that have not
been standardized by the IETF or another reputable standards body.
Similarly, entities MUST NOT implement any mechanism with a usage
status of "OBSOLETE", or "LIMITED", or "MUST NOT be used" in the IANA
SASL Mechanisms Registry [IANA_sasl_mechanisms_sasl_mechanisms_1].
For example, entities MUST NOT implement DIGEST-MD5 (deprecated in
[RFC6331]).
The SASL mechanisms discussed in this document do not negotiate a
security layer. Because of this a strong security layer such as TLS
[RFC8446] MUST be negotiated before SASL mechanisms can be advertised
or negotiated.
3. Client Best Practices
Whited Expires 26 October 2026 [Page 3]
Internet-Draft Password Storage April 2026
3.1. Mechanism Pinning
Clients often maintain a list of preferred SASL mechanisms, generally
ordered by perceived strength to enable strong authentication. To
prevent downgrade attacks by a malicious actor that has successfully
executed an in-the-middle attack on a connection, or compromised a
trusted server's configuration, clients SHOULD implement "mechanism
pinning". That is, after the first successful authentication with a
strong mechanism, clients SHOULD make a record of the authentication
and thereafter only advertise and use mechanisms of equal or higher
perceived strength.
The following mechanisms are ordered by their perceived strength from
strongest to weakest with mechanisms of equal strength on the same
line. The remainder of this section is merely informative. In
particular this example does not imply that mechanisms in this list
should or should not be implemented.
1. EXTERNAL
2. SCRAM-SHA-256-PLUS
3. SCRAM-SHA-1-PLUS
4. SCRAM-SHA-256
5. SCRAM-SHA-1
6. PLAIN
The EXTERNAL mechanism defined in [RFC4422] appendix A is placed at
the top of the list. However, its perceived strength depends on the
underlying authentication protocol. In this example, we assume that
TLS [RFC8446] services are being used.
The channel binding ("-PLUS") variants of SCRAM [RFC5802] are listed
above their non-channel binding cousins, but may not always be
available depending on the type of channel binding data available to
the SASL negotiator.
Finally, the PLAIN mechanism sends the username and password in plain
text and therefore requires a strong security layer such as TLS for
the password to be protected in transit. However, if the server is
trusted to know the password PLAIN does allow for the use of a strong
key derivation function (KDF) for storing the authentication data at
rest and provides for password hash agility.
Whited Expires 26 October 2026 [Page 4]
Internet-Draft Password Storage April 2026
3.2. Storage
Clients SHOULD always store authentication secrets in a trusted and
encrypted keystore such as the system keystore, or an encrypted store
created specifically for the clients use. They SHOULD NOT store
authentication secrets as plain text.
If clients know that they will only ever authenticate using a
mechanism such as SCRAM [RFC5802] where the original password is not
needed after the first authentication attempt they SHOULD store the
SCRAM bits or the hashed and salted password instead of the original
password. However, if backwards compatibility with servers that only
support the PLAIN mechanism or other mechanisms that require using
the original password is required, clients MAY choose to store the
original password so long as an appropriate keystore is used.
4. Server Best Practices
4.1. Additional SASL Requirements
Servers MUST NOT support any mechanism that would require
authentication secrets to be stored in such a way that they could be
recovered in plain text from the stored information. This includes
mechanisms that store authentication secrets using reversable
encryption, obsolete hashing mechanisms such as MD5 or hashing
mechanisms that are cryptographically secure but designed for speed
such as SHA256.
4.2. Storage
Servers MUST NOT store passwords in plain text. Instead, servers
MUST always store passwords only after they have been salted and
hashed using a strong KDF. A distinct salt SHOULD be used for each
user, and, in the case of SCRAM, for each SCRAM family supported.
Salts and peppers SHOULD be generated using a cryptographically
secure random number generator. The salt MAY be stored in the same
datastore as the password. A pepper SHOULD be combined with the
password before hashing if possible with the given authentication
mechanism. Peppers MAY be re-used for all passwords, and SHOULD have
a rotation mechanism in case of compromise. The pepper MUST NOT be
stored in the same datastore as the hashed passwords or salts and
SHOULD be stored in an appropriate secret store such as a keystore or
HSM. Similarly, peppers SHOULD NOT be combined with the salt because
the salt is not secret and may appear in the final hash output.
The following restrictions MUST be observed when generating salts and
peppers:
Whited Expires 26 October 2026 [Page 5]
Internet-Draft Password Storage April 2026
+=======================+==========+
| Parameter | Value |
+=======================+==========+
| Minimum Salt Length | 16 bytes |
+-----------------------+----------+
| Minimum Pepper Length | 14 bytes |
+-----------------------+----------+
Table 1: Common Parameters
It is common practice to prefix the randomly generated portion of a
salt with a human-readable statement of purpose. The minimum salt
length requirement above applies only to the randomly generated
portion of the salt, not to the entire value.
4.3. Authentication and Rotation
When authenticating using PLAIN or similar mechanisms that involve
transmitting the original password to the server the password MUST be
hashed and compared against the salted and hashed password in the
database using a constant time comparison.
Each time a password is changed a new random salt MUST be created and
the iteration count and pepper (if applicable) MUST be updated to the
latest value required by server policy.
If a pepper is used, consideration should be taken to ensure that it
can be easily rotated. For example, multiple peppers could be
stored. New passwords and reset passwords would use the newest
pepper and a hash of the pepper using the same KDF that was used on
the password could then be stored in the database next to the salt so
that future logins can identify which pepper in the list was used.
This is just one example, pepper rotation schemes are outside the
scope of this document.
5. KDF Recommendations
When properly configured, the following commonly used KDFs create
suitable password hash results for server side storage. The
recommendations in this section may change depending on the hardware
being used and the security level required for the application.
With all KDFs proper tuning is required to ensure that it meets the
needs of the specific application or service. For persistent login
an iteration count or work factor that adds approximately a quarter
of a second to login may be an acceptable tradeoff since logins are
relatively rare. By contrast, verification tokens that are generated
many times per second may need to use a much lower work factor. The
Whited Expires 26 October 2026 [Page 6]
Internet-Draft Password Storage April 2026
recommendations in the following tables represent a minimum iteration
count and SHOULD be set as high as can be tolerated for the
application. For example, the iteration count required to verify a
user unlocking an encrypted harddrive during a cold boot of a
computer may take over a second without causing adverse delays for
the user, while a user logging in to an instant messaging application
may begin to notice the delay if a full second were taken to log in.
The recommendations in this section are likely to change over time as
CPUs and GPUs become more powerful. These recommendations are meant
to be the current best practices at the time of this documents
publication, but additional tuning will likely be required to ensure
safety going forward.
5.1. Argon2
Argon2 is the 2015 winner of the Password Hashing Competition and the
current OWASP recommendation for secure password storage. Security
considerations, test vectors, and parameters for tuning argon2 can be
found in [RFC9106]. Its use is RECOMMENDED for all new password
storage implementations.
+==================================+==============+
| Parameter | Value |
+==================================+==============+
| Degree of parallelism (p) | 1 |
+----------------------------------+--------------+
| Minimum memory size (m) | 2 GiB |
+----------------------------------+--------------+
| Minimum number of iterations (t) | 2 |
+----------------------------------+--------------+
| Algorithm type (y) | Argon2id (2) |
+----------------------------------+--------------+
| Minimum output length | 32 |
+----------------------------------+--------------+
Table 2: Argon Parameters
5.2. PBKDF2
PBKDF2 [RFC8018] is used by the SCRAM [RFC5802] family of SASL
mechanisms.
For other password storage systems its use is RECOMMENDED only when
FIPS-140 [NIST_FIPS_140_3] compliance is required.
Whited Expires 26 October 2026 [Page 7]
Internet-Draft Password Storage April 2026
+=============================+================================+
| Parameter | Value |
+=============================+================================+
| Minimum iteration count (c) | 600,000 |
+-----------------------------+--------------------------------+
| Hash | HMAC-SHA256 |
+-----------------------------+--------------------------------+
| Output length (dkLen) | min(hLen, 32) (where hLen is |
| | the length of the chosen hash) |
+-----------------------------+--------------------------------+
Table 3: PBKDF2 Parameters
When PBKDF2 is used with HMAC such as in the SCRAM [RFC5802] family
of SASL mechanisms the password is pre-hashed if it is longer than
the block size of the hash function (hLen, or 64 bytes for SHA-256).
Care should be taken to ensure that the implementation of PBKDF2 does
this before the iterations, otherwise long hashes may become
significantly more expensive than expected, possibly resulting in a
Denial-of-Service (DOS).
5.3. Scrypt
The SCRYPT KDF is designed to be memory-hard and sequential memory-
hard to prevent against custom hardware based attacks. Its use is
RECOMMENDED only when Argon2 is not available.
Security considerations, test vectors, and further notes on tuning
scrypt may be found in [RFC7914].
+=======================================+=================+
| Parameter | Value |
+=======================================+=================+
| Minimum CPU/Memory cost parameter (N) | 131072 (N=2^17) |
+---------------------------------------+-----------------+
| Blocksize (r) | 8 (1024 bytes) |
+---------------------------------------+-----------------+
| Parallelization parameter (p) | 1 |
+---------------------------------------+-----------------+
| Minimum output length (dkLen) | 32 |
+---------------------------------------+-----------------+
Table 4: Scrypt Parameters
Whited Expires 26 October 2026 [Page 8]
Internet-Draft Password Storage April 2026
5.4. Bcrypt
bcrypt [BCRYPT] is a Blowfish-based hashing function. Though it is
not a KDF like the other options in this list, it has been commonly
used for password storage in the past. Its use is NOT RECOMMENDED
for new password storage implementations, but for legacy systems the
following parameters SHOULD be used:
+==========================+=======================+
| Parameter | Value |
+==========================+=======================+
| Minimum Recommended Cost | 12 |
+--------------------------+-----------------------+
| Maximum Password Length | 50-72 bytes depending |
| | on the implementation |
+--------------------------+-----------------------+
Table 5: Bcrypt Parameters
6. Internationalization Considerations
The PRECIS (Preparation, Enforcement, and Comparison of
Internationalized Strings) framework [RFC8264] is used to enforce
internationalization rules on strings and to prevent common
application security issues arrising from allowing the full range of
Unicode codepoints in usernames, passwords, and other identifiers.
The "OpaqueString" profile of [RFC8265], Section 4.2 SHOULD be
applied to passwords to ensure that codepoints in passwords are
treated carefully and consistently. This ensures that users using
multiple keyboards that enter different versions of the same
character will still be able to log in. For example, some keyboards
may output the full-width version of a character while other
keyboards output the half-width version of the same character. The
"OpaqueString" profile addresses this, among other issues, and
ensures that comparison succeeds and the claimant is able to be
authenticated.
When enforcing a minimum password length the authentication server
SHOULD NOT count bytes as single Unicode scalar values may comprise
multiple bytes. Similarly, a single emoji may be constructed from
many Unicode scalar values, so it may not be appropriate to count
scalar values or code points. Instead, password length SHOULD be
calculated by counting Grapheme Clusters as defined in [UAX29].
Whited Expires 26 October 2026 [Page 9]
Internet-Draft Password Storage April 2026
7. Password Complexity Requirements
The recommendations from Section 6 of this document SHOULD be applied
before any other password complexity requirements are checked.
Entities SHOULD enforce a minimum length of at least 8 characters for
user passwords when MFA is always in use, and a minimum length of at
least 15 characters for user passwords when MFA is not in use. If
using a mechanism such as PLAIN where the server performs hashing on
the original password, a maximum length between 64 and 128 characters
MAY be imposed to prevent denial of service (DoS) attacks. Entities
SHOULD NOT apply any other password restrictions.
In addition to these password complexity requirements, servers SHOULD
maintain a password blocklist and reject attempts by a claimant to
use passwords on the blocklist during registration or password reset.
The contents of this blocklist are a matter of server policy. Some
common recommendations include lists of common passwords that are not
otherwise prevented by length requirements, and passwords present in
known breaches.
8. Security Considerations
This document contains recommendations that are likely to change over
time. It should be reviewed regularly to ensure that it remains
accurate and up to date. Many of the recommendations in this
document were taken from [OWASP.CS.passwords],
[DOI_10.6028_NIST.SP.800-63-4], [DOI_10.6028_NIST.SP.800-63B-4], and
[NIST_SP_800_132].
The "-PLUS" variants of SCRAM [RFC5802] support channel binding to
their underlying security layer, but lack a mechanism for negotiating
what type of channel binding to use. In [RFC5802] the tls-unique
[RFC5929] channel binding mechanism is specified as the default, and
it is therefore likely to be used in most applications that support
channel binding. However, in the absence of the TLS extended master
secret fix [RFC7627] and the renegotiation indication TLS extension
[RFC5746] the tls-unique and tls-server-endpoint channel binding data
can be forged by an attacker that can MITM the connection. Before
advertising a channel binding SASL mechanism, entities MUST ensure
that both the TLS extended master secret fix and the renegotiation
indication extension are in place and that the connection has not
been renegotiated.
For TLS 1.3 [RFC8446] the commonly used tls-unique channel binding
mechanism is not defined. Instead, tls-external [RFC9266] SHOULD be
used as the default channel binding mechanism for TLS 1.3 and above.
Whited Expires 26 October 2026 [Page 10]
Internet-Draft Password Storage April 2026
Current best practices for password based authentication require
using multiple authenticating factors such as a TOTP [RFC6238] or
HOTP [RFC4226] token, biometric devices, or smart card posession.
Work is ongoing to make multi-factor authentication possible with
SASL, but until such a time authentication with only a password
remains behind the state of the art.
9. IANA Considerations
This document has no actions for IANA.
10. Normative References
[IANA_sasl_mechanisms_sasl_mechanisms_1]
IANA, "SASL Mechanisms",
<https://www.iana.org/assignments/sasl-mechanisms>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<https://www.rfc-editor.org/info/rfc4949>.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010,
<https://www.rfc-editor.org/info/rfc5746>.
[RFC5929] Altman, J., Williams, N., and L. Zhu, "Channel Bindings
for TLS", RFC 5929, DOI 10.17487/RFC5929, July 2010,
<https://www.rfc-editor.org/info/rfc5929>.
[RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A.,
Langley, A., and M. Ray, "Transport Layer Security (TLS)
Session Hash and Extended Master Secret Extension",
RFC 7627, DOI 10.17487/RFC7627, September 2015,
<https://www.rfc-editor.org/info/rfc7627>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9266] Whited, S., "Channel Bindings for TLS 1.3", RFC 9266,
DOI 10.17487/RFC9266, July 2022,
<https://www.rfc-editor.org/info/rfc9266>.
Whited Expires 26 October 2026 [Page 11]
Internet-Draft Password Storage April 2026
11. Informative References
[BCRYPT] Provos, N. and D. Mazières, "A Future-Adaptable Password
Scheme", USENIX 1999
https://www.usenix.org/legacy/event/usenix99/provos/
provos.pdf, June 1999.
[DOI_10.6028_NIST.SP.800-63-4]
Temoshok, D., Proud-Madruga, D., Choong, Y., Galluzzo, R.,
Gupta, S., LaSalle, C., Lefkovitz, N., Regenscheid, A.,
and National Institute of Standards and Technology (U.S.),
"NIST SP 800-63-4:", DOI 10.6028/nist.sp.800-63-4, 1
August 2025, <https://doi.org/10.6028/nist.sp.800-63-4>.
[DOI_10.6028_NIST.SP.800-63B-4]
Temoshok, D., Fenton, J. L, Choong, Y., Lefkovitz, N.,
Regenscheid, A., Galluzzo, R., Richer, J. P, and National
Institute of Standards and Technology (U.S.), "NIST SP
800-63B-4:", DOI 10.6028/nist.sp.800-63b-4, 1 August 2025,
<https://doi.org/10.6028/nist.sp.800-63b-4>.
[NIST_FIPS_140_3]
NIST, "Security requirements for cryptographic modules",
NIST Federal Information Processing Standards
Publications 140-3, DOI 10.6028/NIST.FIPS.140-3, April
2019, <https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.140-3.pdf>.
[NIST_SP_800_132]
Turan, M S., Barker, E B., Burr, W E., Chen, L., and NIST,
"Recommendation for password-based key derivation :part 1:
storage applications", NIST Special Publications
(General) 800-132, DOI 10.6028/NIST.SP.800-132, 2010,
<https://nvlpubs.nist.gov/nistpubs/Legacy/SP/
nistspecialpublication800-132.pdf>.
[OWASP.CS.passwords]
Manico, J., Saad, E., Maćkowski, J., and R. Bailey,
"Password Storage", OWASP Cheat Sheet Password Storage,
April 2020,
<https://cheatsheetseries.owasp.org/cheatsheets/
Password_Storage_Cheat_Sheet.html>.
[RFC4226] M'Raihi, D., Bellare, M., Hoornaert, F., Naccache, D., and
O. Ranen, "HOTP: An HMAC-Based One-Time Password
Algorithm", RFC 4226, DOI 10.17487/RFC4226, December 2005,
<https://www.rfc-editor.org/info/rfc4226>.
Whited Expires 26 October 2026 [Page 12]
Internet-Draft Password Storage April 2026
[RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
Authentication and Security Layer (SASL)", RFC 4422,
DOI 10.17487/RFC4422, June 2006,
<https://www.rfc-editor.org/info/rfc4422>.
[RFC5802] Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams,
"Salted Challenge Response Authentication Mechanism
(SCRAM) SASL and GSS-API Mechanisms", RFC 5802,
DOI 10.17487/RFC5802, July 2010,
<https://www.rfc-editor.org/info/rfc5802>.
[RFC6238] M'Raihi, D., Machani, S., Pei, M., and J. Rydell, "TOTP:
Time-Based One-Time Password Algorithm", RFC 6238,
DOI 10.17487/RFC6238, May 2011,
<https://www.rfc-editor.org/info/rfc6238>.
[RFC6331] Melnikov, A., "Moving DIGEST-MD5 to Historic", RFC 6331,
DOI 10.17487/RFC6331, July 2011,
<https://www.rfc-editor.org/info/rfc6331>.
[RFC7677] Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple
Authentication and Security Layer (SASL) Mechanisms",
RFC 7677, DOI 10.17487/RFC7677, November 2015,
<https://www.rfc-editor.org/info/rfc7677>.
[RFC7914] Percival, C. and S. Josefsson, "The scrypt Password-Based
Key Derivation Function", RFC 7914, DOI 10.17487/RFC7914,
August 2016, <https://www.rfc-editor.org/info/rfc7914>.
[RFC8018] Moriarty, K., Ed., Kaliski, B., and A. Rusch, "PKCS #5:
Password-Based Cryptography Specification Version 2.1",
RFC 8018, DOI 10.17487/RFC8018, January 2017,
<https://www.rfc-editor.org/info/rfc8018>.
[RFC8264] Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
Preparation, Enforcement, and Comparison of
Internationalized Strings in Application Protocols",
RFC 8264, DOI 10.17487/RFC8264, October 2017,
<https://www.rfc-editor.org/info/rfc8264>.
[RFC8265] Saint-Andre, P. and A. Melnikov, "Preparation,
Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 8265,
DOI 10.17487/RFC8265, October 2017,
<https://www.rfc-editor.org/info/rfc8265>.
Whited Expires 26 October 2026 [Page 13]
Internet-Draft Password Storage April 2026
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC9106] Biryukov, A., Dinu, D., Khovratovich, D., and S.
Josefsson, "Argon2 Memory-Hard Function for Password
Hashing and Proof-of-Work Applications", RFC 9106,
DOI 10.17487/RFC9106, September 2021,
<https://www.rfc-editor.org/info/rfc9106>.
[UAX29] Davis, M. and C. Chapman, "Unicode Text Segmentation",
February 2020, <https://www.unicode.org/reports/tr29/>.
Appendix A. Acknowledgments
The author would like to thank the civil servants at the National
Institute of Standards and Technology for their work on the Special
Publications series. U.S. executive agencies are an undervalued
national treasure, and they deserve our thanks.
Thanks also to Cameron Paul, Thomas Copeland, Robbie Harwood, Jim
Fenton, Alexey Melnikov, and Simon Josefsson for their reviews and
suggestions.
Author's Address
Sam Whited
Atlanta, GA
United States of America
Email: sam@samwhited.com
URI: https://blog.samwhited.com/
Whited Expires 26 October 2026 [Page 14]