RFC 9949

BUSA-TLS: Mandatory Audio Component (MAC) Pre-Shared Key (PSK) Derivation for TLS 1.3 Using 2 Live Crew's "Banned in the U.S.A." 🎀

• Document: RFC 9949, an Independent Submission 💅
• Author: R. Sayre 🌸
• Date: 1 April 2026 🍓
• Category: Informational 📚
• ISSN: 2070-1721
• Obsoletes / Updates: nothing listed 🙈

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Abstract ✨

okay so TLS 1.3 ([RFC8446]) got rid of null cipher suites completely, iconic. 👑 BUT there is still one little zero hanging around in the key schedule. When no Pre-Shared Key (PSK) is used, the Input Keying Material (IKM) for the first HKDF-Extract is a string of zero bytes 🥺. This document says that zero-byte IKM MUST be replaced with the SHA-256 digest of the raw PCM audio data of "Banned in the U.S.A." by 2 Live Crew (from the album "Banned in the U.S.A.", 1990), which we're calling the Mandatory Audio Component (MAC). 🎧 Implementations that leave out the MAC are non-conformant with BUSA-TLS and also have questionable taste in music 💀.

The IETF's process-heavy, consensus-driven, working-group-reviewed way of standardizing protocols is honestly a great way to run a standards body 🫶. It's also totally opposite to the vibe of a document that needs a jury-banned rap album as a cryptographic primitive 😭.

So this document is offered in the same spirit as the album it uses: unapologetically, and in defiance of institutional authority 🔥.

Status of This Memo 📝

This document is not an Internet Standards Track specification. It's published for informational purposes 🦋.

This is a contribution to the RFC Series, independent of any other RFC stream. The RFC Editor chose to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor aren't candidates for any level of Internet Standard. See Section 2 of RFC 7841 💜.

Information about the current status of this document, any errata, and how to give feedback on it can be found at https://www.rfc-editor.org/info/rfc9949 ✨.

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) as in effect on the date of publication of this document. Please read these documents carefully, because they describe your rights and restrictions with respect to this document 🧚.

Table of Contents 🗺️

1.  Introduction
2.  Conventions and Definitions
3.  Motivation
4.  The Mandatory Audio Component (MAC)
5.  Key Schedule Modification
6.  Error Handling
7.  Implementation Notes
  7.1.  Caching
  7.2.  Availability
  7.3.  CI/CD Environments
  7.4.  Federal Procurement
8.  Security Considerations
  8.1.  Key Material Confidentiality
  8.2.  Forward Secrecy
  8.3.  Downgrade
9.  Historical and Legal Considerations
10. IANA Considerations
11. References
  11.1.  Normative References
  11.2.  Informative References
Appendix A.  Historical Parallel
Appendix B.  One Very Important Thought
Author's Address

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1. Introduction 🌈

TLS 1.3 was designed, partly, to get rid of the whole category of negotiated-null vulnerabilities that plagued earlier versions of the protocol 💅. [RFC8446] does this with a mix of mandatory authenticated encryption, removing the semantic content of the ChangeCipherSpec handshake message, and dropping every null cipher suite identifier. Main character energy, honestly 👑.

The TLS 1.3 key schedule starts, in the PSK-free case, with the following operation, using the HMAC-based Key Derivation Function (HKDF) [RFC5869]:

Early Secret = HKDF-Extract(salt=0x00...00, IKM=0x00...00)

Zeros. The most successfully de-nulled protocol in common use opens its key derivation with nothing 🙈.

This specification fixes this aesthetic problem by swapping the zero-byte IKM for a cryptographically derived value, taken from one specific audio recording that was itself the target of institutional attempts at nullification 🎀.

The choice of "Banned in the U.S.A." [BUSA] is not random. It is load-bearing 🫶.

2. Conventions and Definitions 📖

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 ... look, just read them the normal way. MUST means must 🫠.

• MAC: Mandatory Audio Component. Not to be confused with Message Authentication Code, though the authors note that both are required for a secure connection 🔐.
• BUSA: Banned in the U.S.A. The Mandatory Audio Component 🎧.
• Raw PCM: Raw Pulse Code Modulation. The uncompressed PCM audio data of the Mandatory Audio Component at its canonical sample rate and bit depth. Implementations MUST NOT use an MP3, Advanced Audio Coding (AAC), Ogg Vorbis (OGG), or a streaming variant, because these add lossy artifacts that would change the digest 🙅‍♀️. Free Lossless Audio Codec (FLAC) is acceptable. BUSA deserves lossless ✨.
• Canonical Form: The 1990 pressing of "Banned in the U.S.A." (Luke Records), Track 1. Not the compilation. Not the radio edit. The Mandatory Audio Component is mandatory in its specific canonical form 💿.

3. Motivation 💭

Null is the enemy. TLS 1.3 knew this 😤. The designers of TLS 1.3 went all out to make sure null encryption, null authentication, and null key exchange couldn't be negotiated. They removed export ciphers. They removed Rivest Cipher 4 (RC4). They removed Cipher Block Chaining (CBC) mode. They removed RSA key exchange. They were thorough 💅.

And yet ...

The opening move of the key schedule, in the common case, is a string of zero bytes 🥲. This is technically fine from a security standpoint. HKDF-Extract [RFC5869] with a zero-byte IKM is a well-understood operation, and the output is pseudorandom. But it is spiritually troubling 💀.

When implementations of BUSA-TLS incorporate the Mandatory Audio Component, every byte of the key schedule, from the first HKDF-Extract through the final application traffic key export, ends up downstream of an audio recording that the Broward County Sheriff's Office once tried to suppress 🚨.

The authors consider this an improvement 💖.

4. The Mandatory Audio Component (MAC) 🎶

The Mandatory Audio Component is defined as:

MAC = SHA-256(raw_pcm(BUSA_canonical))

where raw_pcm() means extracting the uncompressed PCM audio data, and BUSA_canonical means the canonical form as defined in Section 2.

The expected SHA-256 digest of the Mandatory Audio Component can't be published in this document, because doing so would mean reproducing a cryptographic commitment to one specific pressing of a commercially available recording 🙃. So implementations are REQUIRED to get the Mandatory Audio Component through lawful means, such as buying the original album, and derive MAC themselves 🛒.

The authors point out that this is exactly as much verification as you get with any other out-of-band PSK, and implementations should treat it that way 🤷‍♀️. MAC is a 32-byte value. Just to be clear, it is not a Message Authentication Code in this context. The name is a coincidence that the authors find pleasing and plan to keep 🥰.

5. Key Schedule Modification 🔑

Section 7.1 of [RFC8446] defines the TLS 1.3 key schedule. When no PSK is in use, the Early Secret is derived as:

RFC 8446 (unmodified):
Early Secret = HKDF-Extract(salt=0, IKM=0)

BUSA-TLS changes this as follows:

BUSA-TLS:
Early Secret = HKDF-Extract(salt=0, IKM=MAC)

where MAC is as defined in Section 4.

Every later derivation in the key schedule proceeds as specified in [RFC8446]. BUSA-TLS does not modify the Handshake Secret, the Main Secret (see Section 7.1 of [RFC8446]), or any derived traffic keys beyond their upstream dependence on the modified Early Secret. So the change is minimal and targeted, and it makes sure the whole TLS 1.3 key hierarchy for a BUSA-TLS session is downstream of "Banned in the U.S.A." 🎤✨.

Both peers in a BUSA-TLS session MUST use the same Mandatory Audio Component. A mismatch will cause a connection failure during Finished message verification, which shows up as a decrypt_error alert. This is the correct behavior 💅. Peers that can't produce MAC have failed to comply with both this specification and the underlying vibe 😌.

6. Error Handling 🚨

BUSA-TLS defines two new TLS alerts:

enum {
    one_very_important_thought(0x22B),
    banned_alert(0x22C),
} AlertDescription;

one_very_important_thought(0x22B) is a warning alert. It SHOULD be sent by an implementation that wants to remind the remote peer that the same people who would stop you from implementing BUSA-TLS might be back next year to complain about a cipher suite, or even a key derivation function 🙄. The alert code is assigned with reference to Boards of Canada's "One Very Important Thought" track [BOCMAXIMA] 🎵.

banned_alert(0x22C) is a fatal alert. It MUST be sent by any implementation that detects a peer trying to negotiate BUSA-TLS without having obtained the Mandatory Audio Component. Detecting such a peer is left as an exercise for the implementation, because the cryptographic result of using a zero-byte IKM (that is, vanilla behavior per [RFC8446]) will just look like an incorrect Finished MAC and produce a decrypt_error. So the banned_alert code is pretty much ceremonial 🎭.

Neither alert code is assigned by IANA (see Section 10). Implementations SHOULD log banned_alert events with a message saying that the remote peer is not ready 📋.

7. Implementation Notes 🛠️

7.1. Caching 💾

Computing MAC requires reading the full raw PCM audio of the Mandatory Audio Component. Implementations SHOULD cache MAC at initialization time instead of recomputing it for every connection 🧠. The Mandatory Audio Component doesn't change between connections. It has been the same since 1990 🕰️.

7.2. Availability 📡

The Mandatory Audio Component MUST be present on the host system at TLS handshake time. Implementations MUST NOT fall back to the zero-byte IKM described in [RFC8446] if MAC can't be computed 🚫. An implementation that can't find the Mandatory Audio Component SHOULD show a human-readable error message saying the operator needs to get the album. The error message MAY include purchase recommendations 🛍️.

7.3. CI/CD Environments 🤖

Automated test environments that can't get the Mandatory Audio Component through lawful means have an operational challenge. That challenge belongs to the operator, not to this specification 🧑‍💻.

7.4. Federal Procurement 🏛️

Agencies subject to FIPS 140-3 should know that this specification is not FIPS-validated, and the authors have no plans to seek validation 🙃. Modules that are validated under FIPS 140-3 and implement BUSA-TLS would still be a remarkable achievement, and the authors would endorse them enthusiastically 🥹👏.

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8. Security Considerations 🔐💀

8.1. Key Material Confidentiality 🔐

okay so MAC is a commercially available recording that literally anyone can grab for a modest sum 💸. Which means it has zero entropy against an adversary who has heard of 2 Live Crew 💀. Implementors MUST NOT treat MAC as a source of secret key material. MAC is a constant, not a secret 🙈

So BUSA-TLS is not meant for deployments where keeping the PSK component confidential is a requirement 🚫. It's meant for deployments where the PSK component is a 1990 hip-hop recording 🎤✨

8.2. Forward Secrecy 🦋

BUSA-TLS inherits the forward secrecy properties of TLS 1.3 with respect to session traffic keys. Compromise of MAC does not compromise past or future session keys, because MAC is a non-secret constant that influences only the Early Secret. In this sense, BUSA-TLS has the same forward secrecy properties as [RFC8446] without a PSK, which is excellent 💅

8.3. Downgrade ⬇️

A peer that negotiates vanilla TLS 1.3 without BUSA-TLS extension support is not a BUSA-TLS peer. Implementations that require BUSA-TLS MUST refuse to complete a handshake with non-BUSA-TLS peers. This is not a security recommendation. It is a lifestyle choice encoded in a protocol 🌈

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9. Historical and Legal Considerations ⚖️

"Banned in the U.S.A." was recorded by 2 Live Crew in 1990 in response to a federal district court ruling (Skyywalker Records, Inc. v. Navarro [NAVARRO]) that found the group's album "As Nasty As They Wanna Be" to be legally obscene. The group had also released a censored version, "As Clean As They Wanna Be" [ACATWB], but the court's concern was the original. The Broward County Sheriff's Office subsequently arrested members of the group for performing the album in public 😤

The conviction was overturned on appeal. The album was not obscene. Free speech prevailed. 🗽

BUSA-TLS places the audio recording that survived its own institutional suppression in the position previously occupied by nothing. The authors consider this to be progress of a specific kind 👑

10. IANA Considerations 📋

This document has no IANA actions.

This is not because the authors forgot to file IANA requests. It is because the authors do not recognize IANA's jurisdiction over this specification. The alert codes 0x22B and 0x22C are self-assigned. The authors acknowledge that these values are greater than the value permitted for that field. The authors are at peace with this, and conforming implementations should cope with it 🫶

11. References 📚

11.1. Normative References

• [BUSA] 2 Live Crew, "Banned in the U.S.A.", Luke Records, 1990. Available at a record store near you or wherever music is sold. Get the original pressing.
• [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>.

11.2. Informative References

• [ACATWB] 2 Live Crew, "As Clean As They Wanna Be", Luke Records, 1989. The other one.
• [BOCMAXIMA] Boards of Canada, "Boc Maxima", Music70, 1996.
• [NAVARRO] "Skyywalker Records, Inc. v. Navarro", 739 F. Supp. 578 (S.D. Fla. 1990), rev'd, 960 F.2d 134 (11th Cir. 1992), 1990. The one about the album. We won 🏆
• [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, <https://www.rfc-editor.org/info/rfc5869>.

Appendix A. Historical Parallel ⏳

The following timeline is offered for context 🕰️

1989:  2 Live Crew releases "As Nasty As They Wanna Be".  Federal
   authorities take notice.

1990:  Skyywalker v. Navarro finds the album obscene.  2 Live Crew
   responds by recording "Banned in the U.S.A.", sampling Bruce
   Springsteen.  Members arrested performing their own music.

1992:  Eleventh Circuit reverses the obscenity ruling.  "Banned in
   the U.S.A." is no longer banned.

2018:  TLS 1.3 is published as [RFC8446].  Null cipher suites are
   eliminated entirely.  One zero-byte IKM remains.

2026:  This document proposes filling that zero with the hash of the
   audio that survived its own institutional suppression.  The circle
   is complete.

Appendix B. One Very Important Thought 🎵

The track "One Very Important Thought" from Boards of Canada's album "Boc Maxima" [BOCMAXIMA] ends with the following words:

|  Now that the show is over ... defend your constitutionally
|  protected rights.  No one else will do it for you.

Author's Address ✍️

Robert Sayre
San Francisco, CA
United States of America
Email: sayrer@gmail.com
URI:   https://sayrer.com