The custom C secp256k1 implementation under quartz/src/main/c/ was never
wired into Gradle (no externalNativeBuild block) and only existed for the
3-way benchmark + cross-validation test against ACINQ on JVM/Android.
The C library has been split out to vitorpamplona/libschnorr256k1{,-kmp},
so the in-repo copy is dead weight.
This change replaces it with the published Maven Central artifact
`com.vitorpamplona:schnorr256k1-kmp:1.0.0`, scoped to test/benchmark
configurations only — production crypto continues to use ACINQ
secp256k1-kmp on JVM/Android and the pure-Kotlin Secp256k1 on native.
The Android AAR ships libschnorr256k1_jni.so for arm64-v8a and x86_64,
so the Android benchmark now exercises the C row automatically (no more
manual build_android.sh). On JVM the .so still has to be installed by the
developer; the cross-validation test and triple-benchmark gracefully skip
the C row when System.loadLibrary fails, matching prior behavior.
Verified on JVM: all 13 secp256k1 jvmTest classes pass (188 tests), and
ACINQ vs pure-Kotlin benchmark numbers match the documented baseline
within sandbox noise (verifySchnorr ~15k ops/s, signSchnorr cached
~33k ops/s, pubkeyCreate+Compress ~36k ops/s).
Removes ~5,100 LOC: quartz/src/main/c/ (4,500), Secp256k1InstanceC.*
expect/actual shim (560), Secp256k1C JNI declaration object.
https://claude.ai/code/session_01KnvpK2amcVZKfFiZJvHjVe
The reference port recomputed the inverse DCT cosine tables once per output
pixel — for a 32x24 decode that's ~43k redundant cos() calls. This change
lifts the tables out of the inner loop and caches them across decodes
keyed by (size, componentCount) so subsequent placeholders at the same
target size skip cosine evaluation entirely.
Additional wins:
- AC coefficients unpack into pre-sized DoubleArrays (no ArrayList<Double>
boxing, no post-hoc copy)
- truncated hashes are rejected up-front via a single length check instead
of mid-stream
- LPQA -> sRGB uses an inline branch clamp instead of a
min/max/round/coerceIn chain
Tests: 12 unit tests cover determinism across repeated decodes, cache
clearing, alpha preservation, aspect-ratio preservation both directions,
average-color drift bounds, truncated input rejection, and round-tripping
base64 vs. raw bytes. All green.
Bench: new ThumbHashBenchmark exercises opaque decode, alpha decode,
warm- and cold-cache decode, aspect-ratio probe, and the full
decodeKeepAspectRatio pipeline so the perf delta is visible on device.
Three SHA-256 implementations benchmarked on the same phone:
- sha256Android: Android's MessageDigest (BoringSSL + ARM64 CE hardware)
- sha256OurC: Our C SHA-256 (ARM64 CE hardware via JNI)
- sha256Kotlin: Kotlin's sha256 (platform MessageDigest on Android)
Also add nativeSha256 JNI method to expose our hardware SHA-256.
Why our C matches ACINQ on ARM64 despite different architectures:
- Our 4x64: 16 MUL+UMULH pairs per field mul
- ACINQ 5x52: 25 MUL+UMULH pairs per field mul
- We save 9 multiply pairs (~27ns on Cortex-X3) per fe_mul
- ACINQ saves ~6 normalizations with lazy reduction (~6ns)
- Net advantage: ~21ns per mul × 500 muls/verify > 0
- Plus our SHA-256 uses hardware CE, ACINQ's is software
https://claude.ai/code/session_011KVZhDcV2G7idNWEBz12GY
Add a complete C implementation of secp256k1 elliptic curve operations
alongside the existing Kotlin implementation, enabling direct comparison
and extraction of maximum performance from each platform (ARM64, x86_64).
C Implementation (quartz/src/main/c/secp256k1/):
- field.h/c: 5x52-bit limb field arithmetic with __int128 support and
lazy reduction (12-bit headroom per limb vs Kotlin's fully-packed 4x64)
- scalar.h/c: Scalar mod n arithmetic, GLV decomposition, wNAF encoding
- point.h/c: Jacobian point operations (3M+4S double, 8M+3S mixed add),
GLV+wNAF scalar multiplication, Strauss/Shamir dual scalar multiply,
Montgomery batch-to-affine, precomputed G tables (wNAF-12)
- schnorr.c: BIP-340 Schnorr sign/verify/verifyFast/verifyBatch with
pubkey decompression cache and precomputed tag hash prefixes
- sha256.c: Self-contained SHA-256 for BIP-340 tagged hashes
- secp256k1_c.h: Public API matching the Kotlin Secp256k1 object
- jni_bridge.c: JNI bridge for JVM/Android integration
- benchmark.c: Standalone C benchmark (cmake build)
- CMakeLists.txt: Build system with ARM64/x86_64 optimization flags
Kotlin Integration:
- Secp256k1InstanceC: expect/actual wrapper (commonMain/jvmMain/androidMain/nativeMain)
- Secp256k1C: JVM JNI binding class
- Secp256k1TripleBenchmark: Three-way JVM benchmark (ACINQ vs Kotlin vs Custom C)
- Secp256k1CBenchmark: Android benchmark for the C implementation
Current status: sign works correctly (verified against BIP-340 test vectors),
verify path needs ecmult_double_g debugging (GLV wNAF-12 table issue). The
comb table for ecmult_gen also needs fixing (currently falls back to GLV+wNAF).
Field arithmetic is fully verified: 5x52 limbs with R=0x1000003D10 fold.
https://claude.ai/code/session_011KVZhDcV2G7idNWEBz12GY
Add verifySchnorrBatch to Secp256k1InstanceOurs wrapper and add
Android benchmark tests for batch(8) and batch(16).
To get per-event cost: ns/op ÷ batchSize.
JVM benchmark showed 4-7× speedup over individual verify.
Android results TBD.
https://claude.ai/code/session_01EMY5RnXb9rnsyU2KbXrSaY
Wire verifySchnorrFast (x-check only, no y-parity inversion) into:
- Secp256k1InstanceOurs wrapper for app-level usage
- Android benchmark as verifySchnorrFastOurs for Pixel 8 measurement
Expected: ~15% faster than verifySchnorrOurs (~100μs vs ~120μs on Pixel 8)
https://claude.ai/code/session_01EMY5RnXb9rnsyU2KbXrSaY
Creates Secp256k1Benchmark.kt in the benchmark module using AndroidX
Benchmark (Jetpack Microbenchmark) to measure all secp256k1 operations
on real Android hardware/emulator with proper warmup and statistics.
Benchmarks: verifySchnorr, signSchnorr, compressedPubKeyFor,
secKeyVerify, pubKeyCompress, privateKeyAdd, pubKeyTweakMulCompact.
Run with: ./gradlew :benchmark:connectedAndroidTest
The existing SignVerifyBenchmark already tests sign/verify through
Nip01Crypto, but this new benchmark tests the Secp256k1Instance
operations directly, matching the JVM benchmark for comparison.
https://claude.ai/code/session_01BhU63WUe9AhikZxRdw3Lpg
- Fully converts OpenTimestamp Java codebase to Kotlin, migrating the sync and async HTTP call interfaces to OkHttp and coroutines
- Redesigns parsing of relay commands, messages and filters for performance in Jackson.
- Starts the use of KotlinX Serialization when speed is not a requirement
- Migrates all Jackson field annotations to Kotlin Serialization
- Migrates Regex use in Quarts to Kotlin's Regex class
- Migrates Base64 from Android to Kotlin
- Migrates UUID from Android/Java to Kotlin
- Migrates LRUCache usage from Android/Java to Kotlin collections
- Migrates all String to bytearray conversions to Kotlin methods
- Migrates all System.arraycopy calls to kotlin native ones.
- Separates parsing code from the data classes Companion objects
- Exposes Rfc3986 normalizations to each platform.
- Exposes URI parsing classes to each platform.
- Exposes URL Encoders to each platform.
- Exposes BigDecimal to each platform.
- Exposes the Url Detector to each platform.
- Exposes MacInstances to each platform
- Exposes Diggest instances to each platform.
- Exposes a BitSet to each platform.
- Exposes GZip to each platform.
- Exposes Secp256k1 to each platform.
- Exposes SecureRandom to each platform.
- Exposes Time in seconds to each platform.
- Exposes the LargeCache to each platform.
- Exposes AES CBC and AES GCM encryption/decryption to each platform
- Migrate test assertions to Kotlin Tests
- Exposes Address class to each platform because of the Parceleable
- Creates our own ByteArrayOutputStream.
- Removes Lock features inside the Bloomfilters because we don't need data consistency/
- Migrates UserMetadata parser from Jackson to Kotlin serialization
- Removes the need for Static methods in each tag.
- Adds an event template serializer
- Adds KotlinX Datetime to migrate some of the date-based logs
- Adds support for LibSodium in the JVM platform
- Creates a shared test build for iOS targets
- Fixes several usages of Reflection when serializing classes
- Fixes a bug on loading RelayDB for the HintBloom filter test
- Increases the Bloom filter space to better use hints in the app.
- Removes support for iOS in x86
- Creates a Jackson mapper just for NIP-55, which stays in the Android build only.
- Keeps the event store in the android build as well.
- Removes @Syncronized tags in favor of Mutexes.
- Improved sendAndWaitForResponse NostrClient method to properly account for returns from each relay.
- Removes the need for GlobalScope and async calls in the downloadFirstEvent method.
- Restructures the parser and serialization of the relay messages and commands for performance with Jackson
- Removes the dependency on Jackson's error classes across the codebase.
- Moves the hint to quote tag extension methods to their own packages.
- Speeds up the generation of Bech32 addresses
- Migrates NIP-6 and Blossom uploads to use Kotlin Serialization
Claude