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G7SensorKit on the watch, including but not limited to directAuth capability #80

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G7SensorKit on the watch, including but not limited to directAuth capability #80

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0338684
G7SensorKit-watchOS target and watch direct read
Oct 1, 2026
f146b03
Watch pairing: fast P-256, scan until found, watch display slot
ps2 Sep 30, 2026
99a4efa
Watch acquisition state lives in the manager, not user defaults
ps2 Sep 30, 2026
5e2b3b6
G7CGMManager: configuration sharing; role decided at run time
Oct 1, 2026
c26d928
Drop the one-time migration of the watch's old defaults keys
Oct 1, 2026
10ff9b0
Remove leftover watch acquisition code
Oct 1, 2026
dea30ee
Remove the bounded status read and the Reconnect action
Oct 1, 2026
03838bd
Decide by role and reading mode, not by platform
Oct 1, 2026
2eee5b8
Move the watch acquisition arm into one watchOS-only file
Oct 1, 2026
a195306
G7CGMManager: take localState at adopt
Oct 2, 2026
06cc18e
Watch search note: how long it takes, and the pairing prompt to accept
Oct 5, 2026
daf9195
Watch acquisition: re-check on any wake, not only at launch
Oct 5, 2026
de4e2ab
Watch search note: the pairing prompt is conditional
Oct 5, 2026
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256 changes: 254 additions & 2 deletions G7SensorKit.xcodeproj/project.pbxproj
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58 changes: 58 additions & 0 deletions G7SensorKit.xcodeproj/xcshareddata/xcschemes/G7SensorKit-watchOS.xcscheme
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Original file line number Diff line number Diff line change
@@ -0,0 +1,58 @@
<?xml version="1.0" encoding="UTF-8"?>
<Scheme
LastUpgradeVersion = "1620"
version = "1.3">
<BuildAction
parallelizeBuildables = "YES"
buildImplicitDependencies = "YES">
<BuildActionEntries>
<BuildActionEntry
buildForTesting = "YES"
buildForRunning = "YES"
buildForProfiling = "YES"
buildForArchiving = "YES"
buildForAnalyzing = "YES">
<BuildableReference
BuildableIdentifier = "primary"
BlueprintIdentifier = "FADE00000000000000000305"
BuildableName = "G7SensorKit.framework"
BlueprintName = "G7SensorKit-watchOS"
ReferencedContainer = "container:G7SensorKit.xcodeproj">
</BuildableReference>
</BuildActionEntry>
</BuildActionEntries>
</BuildAction>
<TestAction
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
shouldUseLaunchSchemeArgsEnv = "YES">
<Testables>
</Testables>
</TestAction>
<LaunchAction
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
launchStyle = "0"
useCustomWorkingDirectory = "NO"
ignoresPersistentStateOnLaunch = "NO"
debugDocumentVersioning = "YES"
debugServiceExtension = "internal"
allowLocationSimulation = "YES">
</LaunchAction>
<ProfileAction
buildConfiguration = "Release"
shouldUseLaunchSchemeArgsEnv = "YES"
savedToolIdentifier = ""
useCustomWorkingDirectory = "NO"
debugDocumentVersioning = "YES">
</ProfileAction>
<AnalyzeAction
buildConfiguration = "Debug">
</AnalyzeAction>
<ArchiveAction
buildConfiguration = "Release"
revealArchiveInOrganizer = "YES">
</ArchiveAction>
</Scheme>
109 changes: 3 additions & 106 deletions G7SensorKit/Crypto/G7P256.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -144,121 +144,18 @@ enum G7P256 {
})
}

// MARK: - Point arithmetic

/// Jacobian projective coordinates: (X, Y, Z) is the affine point
/// (X/Z², Y/Z³). Used internally so a scalar multiplication needs one
/// modular inversion at the end instead of one per bit.
private struct Jacobian {
var x: G7BigUInt
var y: G7BigUInt
var z: G7BigUInt

var isInfinity: Bool {
z.isZero
}

static let infinity = Jacobian(x: .one, y: .one, z: .zero)
}

private static func jacobian(from point: G7P256Point) -> Jacobian {
point.isInfinity ? .infinity : Jacobian(x: point.x, y: point.y, z: .one)
}

private static func affine(from point: Jacobian) -> G7P256Point {
guard !point.isInfinity, let zInverse = fieldInverse(point.z) else {
return .infinity
}
let zInverse2 = fieldSquare(zInverse)
let zInverse3 = fieldMul(zInverse2, zInverse)
return G7P256Point(x: fieldMul(point.x, zInverse2), y: fieldMul(point.y, zInverse3))
}

/// Point doubling, using the a = -3 shortcut ("dbl-2001-b").
private static func double(_ point: Jacobian) -> Jacobian {
guard !point.isInfinity, !point.y.isZero else {
return .infinity
}
let delta = fieldSquare(point.z)
let gamma = fieldSquare(point.y)
let beta = fieldMul(point.x, gamma)
let alpha = fieldMul(
G7BigUInt(3),
fieldMul(fieldSub(point.x, delta), fieldAdd(point.x, delta))
)
let eightBeta = fieldMul(G7BigUInt(8), beta)
let x = fieldSub(fieldSquare(alpha), eightBeta)
let z = fieldSub(fieldSub(fieldSquare(fieldAdd(point.y, point.z)), gamma), delta)
let y = fieldSub(
fieldMul(alpha, fieldSub(fieldMul(G7BigUInt(4), beta), x)),
fieldMul(G7BigUInt(8), fieldSquare(gamma))
)
return Jacobian(x: x, y: y, z: z)
}

/// Point addition ("add-2007-bl").
private static func add(_ lhs: Jacobian, _ rhs: Jacobian) -> Jacobian {
if lhs.isInfinity {
return rhs
}
if rhs.isInfinity {
return lhs
}

let z1z1 = fieldSquare(lhs.z)
let z2z2 = fieldSquare(rhs.z)
let u1 = fieldMul(lhs.x, z2z2)
let u2 = fieldMul(rhs.x, z1z1)
let s1 = fieldMul(lhs.y, fieldMul(rhs.z, z2z2))
let s2 = fieldMul(rhs.y, fieldMul(lhs.z, z1z1))

if u1 == u2 {
return s1 == s2 ? double(lhs) : .infinity
}

let h = fieldSub(u2, u1)
let i = fieldSquare(fieldMul(G7BigUInt(2), h))
let j = fieldMul(h, i)
let r = fieldMul(G7BigUInt(2), fieldSub(s2, s1))
let v = fieldMul(u1, i)

let x = fieldSub(fieldSub(fieldSquare(r), j), fieldMul(G7BigUInt(2), v))
let y = fieldSub(
fieldMul(r, fieldSub(v, x)),
fieldMul(G7BigUInt(2), fieldMul(s1, j))
)
let z = fieldMul(
fieldSub(fieldSub(fieldSquare(fieldAdd(lhs.z, rhs.z)), z1z1), z2z2),
h
)
return Jacobian(x: x, y: y, z: z)
}

// MARK: - Public operations
// MARK: - Point arithmetic (fixed-width field, see `G7P256Field`)

static func add(_ lhs: G7P256Point, _ rhs: G7P256Point) -> G7P256Point {
affine(from: add(jacobian(from: lhs), jacobian(from: rhs)))
(G7P256Jacobian(lhs) + G7P256Jacobian(rhs)).affine
}

/// Left-to-right double-and-add. Not constant time: the values being
/// multiplied here are ephemeral handshake scalars on a link that is
/// already physically local, and the alternative is a much larger
/// implementation to audit.
static func multiply(_ point: G7P256Point, by scalar: G7BigUInt) -> G7P256Point {
let scalar = scalar.modulo(order)
guard !scalar.isZero, !point.isInfinity else {
return .infinity
}

let base = jacobian(from: point)
var result = Jacobian.infinity
for index in stride(from: scalar.bitWidth - 1, through: 0, by: -1) {
result = double(result)
if scalar.bit(at: index) {
result = add(result, base)
}
}
return affine(from: result)
return G7P256Jacobian(point).multiplied(byBigEndian: scalar.bigEndianBytes(paddedTo: 32)).affine
}

static func multiplyGenerator(by scalar: G7BigUInt) -> G7P256Point {
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