| name | size-monitor |
| description | Monitor and optimize the signer JAR size to stay under the 1 MB budget. Use when adding new classes or dependencies to signer/, or when the user is concerned about JAR size. |
Signer JAR Size Monitor
The signer MIDlet must fit in a 1 MB JAR (1,048,576 bytes) to run on the Nokia C1-01. This includes all application classes AND the tree-shaken Bouncy Castle crypto library.
Current Budget
| Component | Size | Notes |
|---|
| Application classes | ~50 KB | 27 Java source files |
| Bouncy Castle (pruned) | ~236 KB | After ProGuard tree-shaking |
| Total JAR | ~286 KB | Well under budget |
| Budget remaining | ~738 KB | Available for M1c-M1e features |
Check Current Size
make size-check
ls -la signer/dist/BurnerWallet.jar 2>/dev/null
Size Optimization Strategies
ProGuard Configuration
The build uses ProGuard 7.8.2 with -microedition. Key settings in signer/build.xml:
- Bouncy Castle is injected as
-injars (not -libraryjars) for aggressive tree-shaking
-keep class org.burnerwallet.** preserves all app classes-keep class * extends javax.microedition.midlet.MIDlet preserves the entry point- Unused BC classes are stripped automatically
If Size Grows Too Large
-
Check ProGuard output for which BC classes survived:
jar tf signer/dist/BurnerWallet.jar | grep bouncycastle | wc -l
-
Review unused imports in signer source that pull in BC classes:
grep -r "import org.bouncycastle" signer/src/ | sort -u
-
Consider splitting features across MIDlet suites (last resort)
-
Avoid adding new third-party libraries — every dependency goes through ProGuard
Size Impact Estimates for M1c-M1e
| Feature | Estimated Size Impact |
|---|
| PSBT parser | +15-25 KB |
| BIP143 sighash | +5-10 KB |
| QR code generator | +30-50 KB (depends on library) |
| QR code reader (camera) | +20-40 KB |
| Transaction serializer | +5-10 KB |
| Total M1c-M1e estimate | +75-135 KB |
| Projected total | ~360-420 KB |
Even with all planned features, we should stay well under 1 MB.
When to Run Size Check
- After adding any new Java source file to
signer/src/
- After adding new Bouncy Castle imports
- After modifying ProGuard configuration
- Before every PR that touches
signer/
- As part of CI (automated in
make test)
