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Sign plaintext packets in licensed mode (#10969)

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* feat: sign licensed plaintext packets

Preserve and publish identity keys in licensed mode so existing XEdDSA signatures can authenticate plaintext traffic. Sign licensed broadcasts and direct messages when they fit, while keeping PKI encryption disabled and normal routing behavior unchanged.

* fix(security): persist licensed channel sanitation

* fix(security): close licensed migration lifecycle gaps

* fix(security): address licensed signing review feedback

* test: restore signing globals from Unity teardown

* fix(baseui): allow confirmed ham region selection

* fix(baseui): guard region picker validation

* style: trunk fmt

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Austin <vidplace7@gmail.com>
This commit is contained in:
Benjamin Faershtein
2026-07-27 02:57:15 +00:00
committed by GitHub
co-authored by GitHub Ben Meadors Austin
parent 45cb8e7500
commit 1e982fa78c
15 changed files with 576 additions and 49 deletions
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src/mesh/Router.cpp
+13 -7
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@@ -810,12 +810,17 @@ DecodeState perhapsDecode(meshtastic_MeshPacket *p)
}
bool decrypted = false;
bool pkiAttempted = false;
bool licensedPkiCandidate = false;
bool matchedChannel = false;
ChannelIndex chIndex = 0;
#if !(MESHTASTIC_EXCLUDE_PKI)
meshtastic_NodeInfoLite *ourNode = nullptr;
if (p->channel == 0 && isToUs(p) && p->to > 0 && !isBroadcast(p->to) && rawSize > MESHTASTIC_PKC_OVERHEAD &&
(ourNode = nodeDB->getMeshNode(p->to)) != nullptr && ourNode->public_key.size > 0) {
const bool pkiCandidate = p->channel == 0 && isToUs(p) && p->to > 0 && !isBroadcast(p->to) &&
rawSize > MESHTASTIC_PKC_OVERHEAD && (ourNode = nodeDB->getMeshNode(p->to)) != nullptr &&
ourNode->public_key.size > 0;
if (pkiCandidate && owner.is_licensed) {
licensedPkiCandidate = true;
} else if (pkiCandidate) {
pkiAttempted = true;
LOG_DEBUG("Attempt PKI decryption");
// Resolve the sender's key only for actual PKI-decrypt candidates, not every encrypted channel
@@ -998,7 +1003,8 @@ DecodeState perhapsDecode(meshtastic_MeshPacket *p)
return DecodeState::DECODE_SUCCESS;
} else {
LOG_WARN("No suitable channel found for decoding, hash was 0x%x!", p->channel);
return (matchedChannel || pkiAttempted) ? DecodeState::DECODE_FAILURE : DecodeState::DECODE_OPAQUE;
return (matchedChannel || pkiAttempted || licensedPkiCandidate) ? DecodeState::DECODE_FAILURE
: DecodeState::DECODE_OPAQUE;
}
}
@@ -1064,12 +1070,12 @@ meshtastic_Routing_Error perhapsEncode(meshtastic_MeshPacket *p)
// verification at every XEdDSA-enabled receiver that knows our key.
p->decoded.xeddsa_signature.size = 0;
#if !(MESHTASTIC_EXCLUDE_PKI) && !(MESHTASTIC_EXCLUDE_XEDDSA)
// Sign broadcast packets when the Data still fits a LoRa frame with the signature
// attached. This must be the exact encoded-size criterion, not a payload-size
// heuristic: a heuristic band where we sign-then-fail-TOO_LARGE breaks packets that
// Licensed packets stay plaintext, so sign both broadcasts and unicasts. Normal mode
// continues to sign broadcasts only. Use the exact encoded size: a payload-size heuristic
// where we sign-then-fail-TOO_LARGE breaks packets that
// were deliverable unsigned, and perhapsDecode() applies the mirror-image rule when
// deciding whether an unsigned broadcast from a known signer is a downgrade.
if (!p->pki_encrypted && isBroadcast(p->to) && signedDataFits(&p->decoded)) {
if (!p->pki_encrypted && (owner.is_licensed || isBroadcast(p->to)) && signedDataFits(&p->decoded)) {
if (crypto->xeddsa_sign(p->from, p->id, p->decoded.portnum, p->decoded.payload.bytes, p->decoded.payload.size,
p->decoded.xeddsa_signature.bytes)) {
p->decoded.xeddsa_signature.size = XEDDSA_SIGNATURE_SIZE;