[saag] New I-D: draft-yossif-psea-01 — Post-Session Execution Assurance (authority gap at execution time)

"[email protected], [email protected]" <[email protected]> Fri, 8 May 2026 10:32:22 +0300
Newsgroups gmane.ietf.saag
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List,

I have submitted an Informational Internet-Draft defining a security =
model for verifying human authority at execution time:

  draft-yossif-psea-01
  Post-Session Execution Assurance (PSEA): A Security Model for =
Verifying Authority at the Moment of Action
  https://datatracker.ietf.org/doc/draft-yossif-psea/

The problem statement: session-based security conflates authentication =
(who logged in) with execution authority (who is approving this specific =
action right now). In banking, healthcare, government, and critical =
infrastructure, this gap enables fraud and unauthorized execution within =
technically valid sessions.

PSEA defines five requirements that an implementation must satisfy to =
close this gap:
  1. Authority validated at the moment of execution, not at login
  2. Human presence demonstrated, not inferred from prior authentication
  3. Execution approval bound to a verified device state
  4. Cryptographic proof independent of session tokens or bearer =
credentials
  5. Proof generation independent of network connectivity

The model is intentionally agnostic to biometric modality, cryptographic =
scheme, and attestation mechanism. It defines what must be proven, not =
how.

A reference specification is maintained at =
https://github.com/yuthent/psea-spec and includes:
  - Formal P/S/E/A tier definitions
  - JSON Schema for the proof token
  - STRIDE-based threat model
  - OpenAPI 3.0 verification contract
  - RFC 6979 deterministic test vectors (20 vectors, 4 tiers)
  - Reference verifiers in Python and TypeScript

The draft explicitly distinguishes PSEA from MFA, continuous =
authentication, session hardening, risk-based authentication, and Zero =
Trust =E2=80=94 each of which addresses a different problem.

I am seeking technical review and critique, specifically:
  - Whether the problem definition is sound and the gap is genuinely =
unaddressed by existing models
  - Whether the five conformance requirements in Appendix B are =
technically sufficient
  - Whether the threat model in the reference spec correctly =
characterizes the attack surface
  - Whether this warrants a dedicated BOF or fits within an existing WG =
charter

Mohamad Khalil Yossif
Yuthent
[email protected]
https://yuthent.com/psea


=09
Mohamad Khalil Yossif
CEO =E2=80=93 Yuthent
Founder =E2=80=93 SwiftCrew, MK Digital, MK Electronics

=20
T: +972 50-931-1103 <tel:+972509311103>
E: [email protected] <mailto:[email protected]>
W: yuthent.com <https://yuthent.com/>	  =
<https://www.linkedin.com/in/mohamad-khalil-yossif-4b9781163/>
=20
  <https://yuthent.com/>
This email may contain confidential or sensitive information. If you are =
not the intended recipient, any review, use, disclosure, distribution, =
or copying is prohibited. If you received this message in error, please =
delete it immediately.


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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;"><div><p =
style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><span style=3D"font-family: =
Helvetica; font-size: 12px;">List,</span></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">I have submitted an =
Informational Internet-Draft defining a security model for verifying =
human authority at execution time:</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; =
</span>draft-yossif-psea-01</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>Post-Session Execution =
Assurance (PSEA): A Security Model for Verifying Authority at the Moment =
of Action</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; =
</span>https://datatracker.ietf.org/doc/draft-yossif-psea/</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">The problem statement: =
session-based security conflates authentication (who logged in) with =
execution authority (who is approving this specific action right now). =
In banking, healthcare, government, and critical infrastructure, this =
gap enables fraud and unauthorized execution within technically valid =
sessions.</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">PSEA defines five =
requirements that an implementation must satisfy to close this =
gap:</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>1. Authority validated at =
the moment of execution, not at login</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>2. Human presence =
demonstrated, not inferred from prior authentication</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>3. Execution approval =
bound to a verified device state</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>4. Cryptographic proof =
independent of session tokens or bearer credentials</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>5. Proof generation =
independent of network connectivity</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">The model is intentionally =
agnostic to biometric modality, cryptographic scheme, and attestation =
mechanism. It defines what must be proven, not how.</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">A reference specification is =
maintained at https://github.com/yuthent/psea-spec and =
includes:</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Formal P/S/E/A tier =
definitions</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- JSON Schema for the =
proof token</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- STRIDE-based threat =
model</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- OpenAPI 3.0 verification =
contract</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- RFC 6979 deterministic =
test vectors (20 vectors, 4 tiers)</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Reference verifiers in =
Python and TypeScript</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">The draft explicitly =
distinguishes PSEA from MFA, continuous authentication, session =
hardening, risk-based authentication, and Zero Trust =E2=80=94 each of =
which addresses a different problem.</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">I am seeking technical =
review and critique, specifically:</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Whether the problem =
definition is sound and the gap is genuinely unaddressed by existing =
models</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Whether the five =
conformance requirements in Appendix B are technically =
sufficient</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Whether the threat model =
in the reference spec correctly characterizes the attack =
surface</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-converted-space">&nbsp; </span>- Whether this warrants a =
dedicated BOF or fits within an existing WG charter</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; =
min-height: 14.0px"><br></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">Mohamad Khalil =
Yossif</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">Yuthent</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px =
Helvetica">[email protected]</font></p>
<p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px =
Helvetica">https://yuthent.com/psea</font></p>
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cellspacing=3D"0" border=3D"0" style=3D"direction: ltr !important;">
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                                    <td style=3D"padding-right: 15px; =
text-align: left;">
                                        <img =
src=3D"https://yuthent.com/public/assets/profile.jpg" width=3D"60" =
height=3D"60" alt=3D"Mohamad Khalil Yossif" style=3D"display: block; =
border-radius: 50%; width: 60px; height: 60px; border: 0;">
                                    </td>
                                    <td style=3D"font-family: Arial, =
sans-serif; line-height: 1.2; text-align: left;">
                                        <div style=3D"font-size: 18px; =
font-weight: bold; color: #002b5c;">Mohamad Khalil Yossif</div>
                                        <div style=3D"font-size: 13px; =
color: #333333; margin-top: 2px;">CEO =E2=80=93 Yuthent</div>
                                        <div style=3D"font-size: 11px; =
color: #777777; margin-top: 2px;">Founder =E2=80=93 SwiftCrew, MK =
Digital, MK Electronics</div>
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font-size: 13px; color: #333333; line-height: 1.5; text-align: left;">
                            <strong>T:</strong> <a =
href=3D"tel:+972509311103" style=3D"color: #002b5c; text-decoration: =
none;">+972 50-931-1103</a><br>
                            <strong>E:</strong> <a =
href=3D"mailto:[email protected]" style=3D"color: #002b5c; =
text-decoration: none;">[email protected]</a><br>
                            <strong>W:</strong> <a =
href=3D"https://yuthent.com" style=3D"color: #002b5c; text-decoration: =
none;">yuthent.com</a>
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message in error, please delete it immediately.
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