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refactor: reorganize secp256k1 for clarity without affecting performance

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Extract MutablePoint, AffinePoint, and PointScratch from Point.kt into
PointTypes.kt (140 lines). Rename Point.kt to ECPoint.kt (897 lines)
to match the single top-level declaration (ktlint convention).

Remove dead code:
- addWnafJacobian: private function never called (replaced by
  addWnafMixedPP with effective-affine tables)

Remove 5 KeyCodec wrapper functions from ECPoint that just delegated
(liftX, hasEvenY, parsePublicKey, serializeUncompressed,
serializeCompressed). Callers in Secp256k1.kt and PointTest.kt now
use KeyCodec directly, making ownership clear: KeyCodec owns key
encoding/decoding, ECPoint owns point arithmetic.

Update Secp256k1.kt header documentation with current benchmark
numbers (verify 1.7x, sign 0.9x faster than native, etc.) and
a concise list of optimizations.

No functional or performance changes — all 170 tests pass, benchmark
numbers unchanged.

https://claude.ai/code/session_017UbWduFi1sLUsgVUMUH2nx
This commit is contained in:
Claude
2026-04-08 01:10:01 +00:00
parent c7b164b845
commit fc690d66c7
4 changed files with 198 additions and 278 deletions
Download Patch File Download Diff File Expand all files Collapse all files
quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/Point.kt → quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/ECPoint.kt
+16 -214
View File
@@ -24,112 +24,29 @@ package com.vitorpamplona.quartz.utils.secp256k1
// ELLIPTIC CURVE POINT OPERATIONS ON secp256k1 // ELLIPTIC CURVE POINT OPERATIONS ON secp256k1
// ===================================================================================== // =====================================================================================
// //
// This file implements point arithmetic on the secp256k1 elliptic curve: y² = x³ + 7 (mod p). // Point arithmetic on the secp256k1 curve: y² = x³ + 7 (mod p).
// It provides point addition, doubling, scalar multiplication, and serialization. // See PointTypes.kt for MutablePoint, AffinePoint, and PointScratch.
//
// JACOBIAN COORDINATES
// ====================
// Points are stored in Jacobian projective coordinates (X, Y, Z) which represent the
// affine point (X/Z², Y/Z³). This avoids expensive field inversions during intermediate
// steps of scalar multiplication — inversion is only needed once at the very end to
// convert back to affine (x, y) form.
//
// The "point at infinity" (identity element) is represented by Z = 0.
// //
// POINT FORMULAS // POINT FORMULAS
// ============== // ==============
// - doublePoint: 3M+4S (uses fe_half for L=(3/2)·X², same as libsecp256k1) // - doublePoint: 3M+4S (uses fe_half for L=(3/2)·X², same as libsecp256k1)
// - addMixed (Jacobian + Affine): 8M+3S (used for precomputed table lookups) // - addMixed (Jacobian + Affine): 8M+3S (precomputed table lookups)
// - addPoints (Jacobian + Jacobian): 11M+5S (used when both points are Jacobian) // - addPoints (Jacobian + Jacobian): 11M+5S (both points Jacobian)
// //
// SCALAR MULTIPLICATION STRATEGIES // SCALAR MULTIPLICATION
// ================================ // =====================
// Three methods are used depending on the context: // 1. mulG (Generator): Comb method, only 3 doublings + ~43 table lookups.
// 2. mul (Arbitrary): GLV + wNAF-5, ~130 shared doublings.
// 3. mulDoubleG (Verify: s·G + e·P): Strauss/Shamir + GLV + wNAF, 4 streams.
// //
// 1. mulG (Generator multiplication): Comb method (Hamburg 2012). // PRECOMPUTED TABLES (lazily initialized)
// Arranges scalar bits into a 4×66 matrix, processes 4 rows with 11 table lookups // =======================================
// each. Only 3 doublings total. Uses a precomputed 704-entry affine table (~45KB). // - combTable: 704 affine points for mulG (~45KB)
// Cost: ~43 mixed additions + 3 doublings ≈ 494 field ops. // - gOddTable: 1024 affine points for G-side wNAF-12 (~128KB)
// Used by: pubkeyCreate, signSchnorr. // - gLamTable: 1024 affine points for λ(G)-side wNAF-12 (~128KB)
// // - pTableCache: 256-entry cache of P-side wNAF tables (~256KB, for verify)
// 2. mul (Arbitrary point multiplication): GLV endomorphism + wNAF-5 (Glv.kt).
// Splits the 256-bit scalar into two ~128-bit halves via the secp256k1 endomorphism,
// then processes both with wNAF encoding in a single pass of ~130 shared doublings.
// P-side tables are batch-inverted to affine (effective-affine technique) so the
// main loop uses addMixed (8M+3S) instead of addPoints (11M+5S), saving ~4M per add.
// Used by: pubKeyTweakMul (ECDH), ecdhXOnly.
//
// 3. mulDoubleG (Verification: s·G + e·P): Strauss/Shamir trick with GLV + wNAF.
// Splits both scalars via GLV into 4 half-scalar streams. G-side uses a precomputed
// 1024-entry affine wNAF-12 table (~128KB); P-side tables batch-inverted to affine.
// All 4 streams share ~130 doublings with mixed additions throughout.
// Used by: verifySchnorr.
//
// BATCH INVERSION
// ===============
// Montgomery's trick: convert n Jacobian→affine with 1 inversion + 3(n-1) muls instead
// of n individual inversions. Used for wNAF table construction and G table initialization.
//
// PRECOMPUTED TABLES
// ==================
// All tables are lazily initialized on first use (Kotlin `by lazy`):
// - combTable: 704 affine points for mulG (~45KB, built once per process)
// - gOddTable: 1024 affine points for G-side wNAF-12 (~128KB, batch-inverted)
// - gLamTable: 1024 affine points for λ(G)-side wNAF-12 (~128KB, derived from gOddTable)
//
// Note: C libsecp256k1 uses WINDOW_G=15 (8192 entries, 1MB) as compile-time .rodata.
// On JVM, w=15 is slower due to cache pressure from heap-allocated AffinePoint objects.
// w=12 (1024 entries, ~128KB) is the sweet spot — fits in L2, fewer additions than w=8.
// ===================================================================================== // =====================================================================================
/**
* Mutable Jacobian point for in-place computation.
*
* Points are mutable to avoid allocating new objects during the inner loop of scalar
* multiplication, which performs thousands of doublings and additions per operation.
*/
internal class MutablePoint(
val x: LongArray = LongArray(4),
val y: LongArray = LongArray(4),
val z: LongArray = LongArray(4),
) {
fun isInfinity(): Boolean = U256.isZero(z)
fun setInfinity() {
for (i in 0 until 4) {
x[i] = 0L
z[i] = 0L
}
y[0] = 1L
for (i in 1 until 4) y[i] = 0L
}
fun copyFrom(other: MutablePoint) {
other.x.copyInto(x)
other.y.copyInto(y)
other.z.copyInto(z)
}
fun setAffine(
ax: LongArray,
ay: LongArray,
) {
ax.copyInto(x)
ay.copyInto(y)
z[0] = 1L
for (i in 1 until 4) z[i] = 0L
}
}
/**
* Affine point (x, y) — no Z coordinate.
* Used for precomputed tables where we want compact storage and mixed addition.
*/
internal class AffinePoint(
val x: LongArray = LongArray(4),
val y: LongArray = LongArray(4),
)
internal object ECPoint { internal object ECPoint {
// ==================== Generator point G ==================== // ==================== Generator point G ====================
@@ -328,69 +245,7 @@ internal object ECPoint {
} }
} }
// ==================== Thread-local scratch buffers ==================== // ==================== Thread-local scratch ====================
/**
* Scratch space for point operations. Each thread gets its own set of temporary
* field elements and a wide buffer to avoid allocation and ThreadLocal lookups
* in the inner loops. The 12 temp buffers (t[0]..t[11]) are shared across
* doublePoint and addPoints — this is safe because these functions only call
* each other in the equal-point degenerate case, which returns immediately
* after the recursive call without using the temps further.
*
* The wide buffer (LongArray(8)) is pre-fetched once per top-level operation
* and passed through to FieldP.mul/sqr, avoiding ~500+ ThreadLocal.get() calls
* per scalar multiplication (~20-30ns each on JVM).
*/
internal class PointScratch {
val t = Array(12) { LongArray(4) }
val dblCopy = MutablePoint() // Copy buffer for in-place doubling (out === input)
val w = LongArray(8) // Wide buffer for FieldP.mul/sqr — shared, avoids ThreadLocal
// Pre-allocated scratch for wNAF encoding (avoids IntArray allocation per call).
// Size 145 = 129 (max bits after GLV split) + 15 (max window) + 1 (headroom).
val wnaf1 = IntArray(145)
val wnaf2 = IntArray(145)
val wnaf3 = IntArray(145) // mulDoubleG needs 4 wNAF arrays
val wnaf4 = IntArray(145)
val wnafTmp = LongArray(4) // scratch for wnaf scalar copy (GLV scalars are up to 4 limbs)
// Pre-allocated scratch for wNAF mixed addition
val mixTmp = MutablePoint()
val mixNegY = LongArray(4)
// Pre-allocated P-side tables for mul/mulDoubleG (avoids ~80 LongArray allocs per call)
val pOddJac = Array(8) { MutablePoint() }
val pLamOddJac = Array(8) { MutablePoint() }
val pOddAff = Array(8) { AffinePoint() }
val pLamOddAff = Array(8) { AffinePoint() }
val p2 = MutablePoint() // doublePoint temp for table building
// Pre-allocated batch inversion temps (avoids 12 LongArray allocs per call)
val cumZ = Array(8) { LongArray(4) }
val batchInv = LongArray(4)
val batchZInv = LongArray(4)
val batchZInv2 = LongArray(4)
val batchZInv3 = LongArray(4)
// Pre-allocated scratch for Glv.splitScalar (avoids ~26 LongArray allocs per call)
val splitWide = LongArray(8) // mulShift384 and ScalarN.mulTo scratch
val splitT1 = LongArray(4) // temporary for mul results
val splitT2 = LongArray(4) // temporary for mul results
val splitK1 = LongArray(4) // output k1
val splitK2 = LongArray(4) // output k2
// Pre-allocated scratch for verifySchnorr (avoids per-call allocations)
val verifyPx = LongArray(4)
val verifyPy = LongArray(4)
val verifyR = LongArray(4)
val verifyS = LongArray(4)
val verifyE = LongArray(4)
val verifyRx = LongArray(4)
val verifyRy = LongArray(4)
val verifyPPoint = MutablePoint()
val verifyResult = MutablePoint()
}
private val scratch = ScratchLocal { PointScratch() } private val scratch = ScratchLocal { PointScratch() }
@@ -883,33 +738,6 @@ internal object ECPoint {
return true return true
} }
/** Process one wNAF digit with full Jacobian addition (for P-side tables). */
private fun addWnafJacobian(
out: MutablePoint,
tmp: MutablePoint,
negScratch: MutablePoint,
wnafDigits: IntArray,
bitIndex: Int,
table: Array<MutablePoint>,
glvNeg: Boolean,
s: PointScratch,
) {
if (bitIndex >= wnafDigits.size) return
val d = wnafDigits[bitIndex]
if (d == 0) return
val idx = (if (d > 0) d else -d) / 2
val effectiveNeg = (d < 0) xor glvNeg
if (!effectiveNeg) {
addPoints(tmp, out, table[idx], s)
} else {
table[idx].x.copyInto(negScratch.x)
FieldP.neg(negScratch.y, table[idx].y)
table[idx].z.copyInto(negScratch.z)
addPoints(tmp, out, negScratch, s)
}
out.copyFrom(tmp)
}
// ==================== Batch Affine Conversion (Montgomery's Trick) ==================== // ==================== Batch Affine Conversion (Montgomery's Trick) ====================
/** /**
@@ -1066,30 +894,4 @@ internal object ECPoint {
FieldP.mul(outX, p.x, zInv2) FieldP.mul(outX, p.x, zInv2)
return true return true
} }
// ==================== Key Encoding (delegates to KeyCodec) ====================
fun liftX(
outX: LongArray,
outY: LongArray,
x: LongArray,
) = KeyCodec.liftX(outX, outY, x)
fun hasEvenY(y: LongArray) = KeyCodec.hasEvenY(y)
fun parsePublicKey(
pubkey: ByteArray,
outX: LongArray,
outY: LongArray,
) = KeyCodec.parsePublicKey(pubkey, outX, outY)
fun serializeUncompressed(
x: LongArray,
y: LongArray,
) = KeyCodec.serializeUncompressed(x, y)
fun serializeCompressed(
x: LongArray,
y: LongArray,
) = KeyCodec.serializeCompressed(x, y)
} }
quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/PointTypes.kt
+140
View File
@@ -0,0 +1,140 @@
/*
* Copyright (c) 2025 Vitor Pamplona
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
* Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package com.vitorpamplona.quartz.utils.secp256k1
/**
* Mutable Jacobian point for in-place computation.
*
* Points are stored in Jacobian projective coordinates (X, Y, Z) which represent
* the affine point (X/Z², Y/Z³). This avoids expensive field inversions during
* intermediate steps — inversion is only needed once at the end to convert back
* to affine (x, y) form.
*
* The "point at infinity" (identity element) is represented by Z = 0.
*
* Mutable to avoid allocating new objects during the inner loop of scalar
* multiplication, which performs thousands of doublings and additions per operation.
*/
internal class MutablePoint(
val x: LongArray = LongArray(4),
val y: LongArray = LongArray(4),
val z: LongArray = LongArray(4),
) {
fun isInfinity(): Boolean = U256.isZero(z)
fun setInfinity() {
for (i in 0 until 4) {
x[i] = 0L
z[i] = 0L
}
y[0] = 1L
for (i in 1 until 4) y[i] = 0L
}
fun copyFrom(other: MutablePoint) {
other.x.copyInto(x)
other.y.copyInto(y)
other.z.copyInto(z)
}
fun setAffine(
ax: LongArray,
ay: LongArray,
) {
ax.copyInto(x)
ay.copyInto(y)
z[0] = 1L
for (i in 1 until 4) z[i] = 0L
}
}
/**
* Affine point (x, y) — no Z coordinate.
* Used for precomputed tables where we want compact storage and mixed addition.
*/
internal class AffinePoint(
val x: LongArray = LongArray(4),
val y: LongArray = LongArray(4),
)
/**
* Pre-allocated scratch space for point operations. Each thread gets its own
* instance via [ScratchLocal] to avoid allocation and ThreadLocal lookups in the
* inner loops of scalar multiplication.
*
* The 12 temp buffers (t[0]..t[11]) are shared across doublePoint and addPoints —
* this is safe because these functions only call each other in the equal-point
* degenerate case, which returns immediately after the recursive call without
* using the temps further.
*
* The wide buffer (LongArray(8)) is pre-fetched once per top-level operation and
* passed through to FieldP.mul/sqr, avoiding ~500+ ThreadLocal.get() calls per
* scalar multiplication (~20-30ns each on JVM).
*/
internal class PointScratch {
val t = Array(12) { LongArray(4) }
val dblCopy = MutablePoint() // Copy buffer for in-place doubling (out === input)
val w = LongArray(8) // Wide buffer for FieldP.mul/sqr — shared, avoids ThreadLocal
// Pre-allocated scratch for wNAF encoding (avoids IntArray allocation per call).
// Size 145 = 129 (max bits after GLV split) + 15 (max window) + 1 (headroom).
val wnaf1 = IntArray(145)
val wnaf2 = IntArray(145)
val wnaf3 = IntArray(145) // mulDoubleG needs 4 wNAF arrays
val wnaf4 = IntArray(145)
val wnafTmp = LongArray(4) // scratch for wnaf scalar copy (GLV scalars are up to 4 limbs)
// Pre-allocated scratch for wNAF mixed addition
val mixTmp = MutablePoint()
val mixNegY = LongArray(4)
// Pre-allocated P-side tables for mul/mulDoubleG (avoids ~80 LongArray allocs per call)
val pOddJac = Array(8) { MutablePoint() }
val pLamOddJac = Array(8) { MutablePoint() }
val pOddAff = Array(8) { AffinePoint() }
val pLamOddAff = Array(8) { AffinePoint() }
val p2 = MutablePoint() // doublePoint temp for table building
// Pre-allocated batch inversion temps (avoids 12 LongArray allocs per call)
val cumZ = Array(8) { LongArray(4) }
val batchInv = LongArray(4)
val batchZInv = LongArray(4)
val batchZInv2 = LongArray(4)
val batchZInv3 = LongArray(4)
// Pre-allocated scratch for Glv.splitScalar (avoids ~26 LongArray allocs per call)
val splitWide = LongArray(8) // mulShift384 and ScalarN.mulTo scratch
val splitT1 = LongArray(4) // temporary for mul results
val splitT2 = LongArray(4) // temporary for mul results
val splitK1 = LongArray(4) // output k1
val splitK2 = LongArray(4) // output k2
// Pre-allocated scratch for verifySchnorr (avoids per-call allocations)
val verifyPx = LongArray(4)
val verifyPy = LongArray(4)
val verifyR = LongArray(4)
val verifyS = LongArray(4)
val verifyE = LongArray(4)
val verifyRx = LongArray(4)
val verifyRy = LongArray(4)
val verifyPPoint = MutablePoint()
val verifyResult = MutablePoint()
}
quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/Secp256k1.kt
+31 -53
View File
@@ -25,59 +25,37 @@ import com.vitorpamplona.quartz.utils.sha256.sha256
/** /**
* Pure Kotlin implementation of secp256k1 elliptic curve operations for Nostr. * Pure Kotlin implementation of secp256k1 elliptic curve operations for Nostr.
* *
* This replaces the native fr.acinq.secp256k1 JNI bindings with a portable KMP * Portable KMP implementation that runs on all Kotlin targets (JVM, Android, iOS,
* implementation that runs on all Kotlin targets (JVM, Android, iOS, Linux) without * Linux) without requiring platform-specific native libraries.
* requiring platform-specific native libraries.
* *
* Provides only the operations used by Nostr: * Provides only the operations used by Nostr:
* - [pubkeyCreate] / [pubKeyCompress]: Key generation * - [pubkeyCreate] / [pubKeyCompress]: Key generation
* - [secKeyVerify]: Key validation * - [secKeyVerify]: Key validation
* - [signSchnorr] / [verifySchnorr]: BIP-340 Schnorr signatures (NIP-01) * - [signSchnorr] / [signSchnorrWithPubKey] / [verifySchnorr]: BIP-340 Schnorr (NIP-01)
* - [privKeyTweakAdd]: BIP-32 key derivation (NIP-06) * - [privKeyTweakAdd]: BIP-32 key derivation (NIP-06)
* - [pubKeyTweakMul] / [ecdhXOnly]: ECDH shared secrets (NIP-04, NIP-44) * - [pubKeyTweakMul] / [ecdhXOnly]: ECDH shared secrets (NIP-04, NIP-44)
* *
* Performance on Java 21 (vs native C/JNI secp256k1, well-warmed): * Performance on JVM (vs native C/JNI secp256k1, 2000+ warmup, 3000-5000 iterations):
* verify ~8,000 ops/s (3.4× native) — Strauss + GLV + wNAF-12 * verify ~15,000 ops/s (1.7× native, with pubkey cache)
* sign ~26,000 ops/s (1.1× native) — comb method (cached pubkey) * sign ~18,000 ops/s (1.5× native)
* pubCreate ~36,000 ops/s (1.6× native) — comb method, 3 doublings * sign(cached) ~28,000 ops/s (0.9× — FASTER than native)
* ECDH ~11,000 ops/s (2.8× native) — GLV + wNAF-5, effective-affine * pubCreate ~38,000 ops/s (1.3× native)
* compress ~7M ops/s (1.7× FASTER) — pure Kotlin, no JNI overhead * ECDH ~14,000 ops/s (2.0× native)
* secKeyVerify ~8M ops/s (1.2× FASTER) — scalar range check, no JNI
* *
* Architecture: * Key optimizations:
* Field arithmetic uses 4×64-bit limbs (LongArray(4)) with Math.unsignedMultiplyHigh * - Unrolled 4×64-bit field arithmetic (mulWide, sqrWide, addTo, subTo)
* (Java 18+, single UMULH instruction) for 64×64→128-bit products. 16 products per * - GLV endomorphism + wNAF + comb method + Strauss/Shamir
* field multiply vs C's 25 (5×52-bit limbs), but each C product is a single native * - Ping-pong point buffers (eliminates copyFrom in scalar mul loops)
* 128-bit MUL instruction vs our UMULH + MUL + carry propagation (~7 insns total). * - Pre-allocated ThreadLocal scratch (eliminates ~130 allocs/operation)
* - Pubkey decompression cache (skips sqrt for repeated pubkeys)
* - P-side wNAF table cache (skips table build for repeated pubkeys)
* - Direct unsigned multiplyHigh fallback (faster on Android < API 31)
* *
* Per-doublePoint cost analysis (instruction-level, vs C libsecp256k1): * Remaining gap vs C libsecp256k1:
* mul/sqr (7 ops): Kotlin ~1,204 insns vs C ~455 insns (2.6× — UMULH overhead) * - No lazy reduction (4×64 limbs fully packed; C's 5×52 have 12-bit headroom)
* add/neg/half: Kotlin ~312 insns vs C ~75 insns (4.2× — no lazy reduction) * - Fermat inversion instead of safegcd (safegcd slower on JVM)
* Total: Kotlin ~1,516 insns vs C ~530 insns (2.9× — matches benchmarks) * - WINDOW_G=12 vs 15 (JVM heap tables cause cache pressure at w=15)
* * - No constant-time guarantees (not needed for Nostr)
* Optimizations implemented (matching or adapted from libsecp256k1):
* - Math.unsignedMultiplyHigh (Java 18+): eliminates 4-insn signed→unsigned correction
* - GLV endomorphism: splits 256-bit scalars into 2×128-bit halves
* - wNAF encoding: windowed non-adjacent form for sparse addition patterns
* - Comb method: generator multiplication with only 3 doublings (Hamburg 2012)
* - Strauss/Shamir: interleaved multi-scalar multiplication for verification
* - Effective-affine: batch-inverts wNAF tables for cheaper mixed adds (saves ~4M/add)
* - Shared Z inversion: GLV table pairs share Z coords, one inversion for both
* - Batch inversion: Montgomery's trick (1 inv + 3(n-1) muls for n inversions)
* - Pre-allocated scratch: ThreadLocal PointScratch eliminates ~130 allocs/operation
* - Dedicated squaring: 10 products vs 16 for general multiplication
* - secp256k1-specific reduceSelf: single branch on a[3]==-1 (>99.99% fast path)
*
* Differences from C libsecp256k1 (due to JVM constraints):
* - No lazy reduction (4×64 limbs have no headroom; C's 5×52 limbs have 12-bit spare
* capacity per limb, allowing 3-8 chained add/sub without normalizing — this accounts
* for 24% of the remaining per-operation gap)
* - Fermat inversion (255 sqr + 15 mul) instead of safegcd (safegcd is slower on JVM
* due to 128-bit arithmetic overhead in the inner divstep matrix multiply)
* - WINDOW_G=12 instead of 15 (JVM heap-allocated tables cause cache pressure at
* larger sizes; C uses contiguous compile-time .rodata arrays)
* - No constant-time guarantees (not needed for Nostr — secrets are nonces, not
* long-term keys exposed to timing side-channels)
*/ */
object Secp256k1 { object Secp256k1 {
// ==================== Cached BIP-340 tag hash prefixes ==================== // ==================== Cached BIP-340 tag hash prefixes ====================
@@ -145,7 +123,7 @@ object Secp256k1 {
} }
// Cache miss — compute sqrt and store // Cache miss — compute sqrt and store
if (!ECPoint.liftX(outX, outY, U256.fromBytes(pub))) return false if (!KeyCodec.liftX(outX, outY, U256.fromBytes(pub))) return false
pubkeyCache[slot] = CachedPubkey(pub.copyOf(), outX.copyOf(), outY.copyOf()) pubkeyCache[slot] = CachedPubkey(pub.copyOf(), outX.copyOf(), outY.copyOf())
return true return true
@@ -163,7 +141,7 @@ object Secp256k1 {
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
check(ECPoint.toAffine(p, x, y)) check(ECPoint.toAffine(p, x, y))
return ECPoint.serializeUncompressed(x, y) return KeyCodec.serializeUncompressed(x, y)
} }
/** /**
@@ -275,7 +253,7 @@ object Secp256k1 {
check(ECPoint.toAffine(pubPoint, px, py)) check(ECPoint.toAffine(pubPoint, px, py))
val xOnlyPub = U256.toBytes(px) val xOnlyPub = U256.toBytes(px)
return signSchnorrInternal(data, d0, xOnlyPub, ECPoint.hasEvenY(py), auxrand) return signSchnorrInternal(data, d0, xOnlyPub, KeyCodec.hasEvenY(py), auxrand)
} }
/** /**
@@ -349,7 +327,7 @@ object Secp256k1 {
val ry = LongArray(4) val ry = LongArray(4)
check(ECPoint.toAffine(rPoint, rx, ry)) check(ECPoint.toAffine(rPoint, rx, ry))
val k = if (ECPoint.hasEvenY(ry)) k0 else ScalarN.neg(k0) val k = if (KeyCodec.hasEvenY(ry)) k0 else ScalarN.neg(k0)
// Challenge: e = H(R || P || msg) // Challenge: e = H(R || P || msg)
val chalInput = ByteArray(64 + 32 + 32 + data.size) val chalInput = ByteArray(64 + 32 + 32 + data.size)
@@ -426,7 +404,7 @@ object Secp256k1 {
val rx = sc.verifyRx val rx = sc.verifyRx
val ry = sc.verifyRy val ry = sc.verifyRy
if (!ECPoint.toAffine(result, rx, ry)) return false if (!ECPoint.toAffine(result, rx, ry)) return false
if (!ECPoint.hasEvenY(ry)) return false if (!KeyCodec.hasEvenY(ry)) return false
return U256.cmp(rx, r) == 0 return U256.cmp(rx, r) == 0
} }
@@ -451,7 +429,7 @@ object Secp256k1 {
require(tweak.size == 32) require(tweak.size == 32)
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
check(ECPoint.parsePublicKey(pubkey, x, y)) check(KeyCodec.parsePublicKey(pubkey, x, y))
val scalar = U256.fromBytes(tweak) val scalar = U256.fromBytes(tweak)
require(ScalarN.isValid(scalar)) require(ScalarN.isValid(scalar))
@@ -464,9 +442,9 @@ object Secp256k1 {
check(ECPoint.toAffine(result, rx, ry)) check(ECPoint.toAffine(result, rx, ry))
return if (pubkey.size == 33) { return if (pubkey.size == 33) {
ECPoint.serializeCompressed(rx, ry) KeyCodec.serializeCompressed(rx, ry)
} else { } else {
ECPoint.serializeUncompressed(rx, ry) KeyCodec.serializeUncompressed(rx, ry)
} }
} }
@@ -498,7 +476,7 @@ object Secp256k1 {
// Use liftX which returns the even-y variant. // Use liftX which returns the even-y variant.
val px = LongArray(4) val px = LongArray(4)
val py = LongArray(4) val py = LongArray(4)
check(ECPoint.liftX(px, py, x)) { "Not a valid x-coordinate on secp256k1" } check(KeyCodec.liftX(px, py, x)) { "Not a valid x-coordinate on secp256k1" }
val p = MutablePoint() val p = MutablePoint()
p.setAffine(px, py) p.setAffine(px, py)
quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/utils/secp256k1/PointTest.kt
+11 -11
View File
@@ -286,10 +286,10 @@ class PointTest {
fun liftXGenerator() { fun liftXGenerator() {
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertTrue(ECPoint.liftX(x, y, ECPoint.GX)) assertTrue(KeyCodec.liftX(x, y, ECPoint.GX))
assertEquals(toHex(ECPoint.GX), toHex(x)) assertEquals(toHex(ECPoint.GX), toHex(x))
// liftX returns even y // liftX returns even y
assertTrue(ECPoint.hasEvenY(y)) assertTrue(KeyCodec.hasEvenY(y))
} }
@Test @Test
@@ -297,27 +297,27 @@ class PointTest {
// p itself is not a valid x coordinate // p itself is not a valid x coordinate
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertFalse(ECPoint.liftX(x, y, FieldP.P)) assertFalse(KeyCodec.liftX(x, y, FieldP.P))
} }
// ==================== Serialization round-trips ==================== // ==================== Serialization round-trips ====================
@Test @Test
fun compressDecompressRoundTrip() { fun compressDecompressRoundTrip() {
val compressed = ECPoint.serializeCompressed(ECPoint.GX, ECPoint.GY) val compressed = KeyCodec.serializeCompressed(ECPoint.GX, ECPoint.GY)
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertTrue(ECPoint.parsePublicKey(compressed, x, y)) assertTrue(KeyCodec.parsePublicKey(compressed, x, y))
assertEquals(toHex(ECPoint.GX), toHex(x)) assertEquals(toHex(ECPoint.GX), toHex(x))
assertEquals(toHex(ECPoint.GY), toHex(y)) assertEquals(toHex(ECPoint.GY), toHex(y))
} }
@Test @Test
fun uncompressedRoundTrip() { fun uncompressedRoundTrip() {
val uncompressed = ECPoint.serializeUncompressed(ECPoint.GX, ECPoint.GY) val uncompressed = KeyCodec.serializeUncompressed(ECPoint.GX, ECPoint.GY)
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertTrue(ECPoint.parsePublicKey(uncompressed, x, y)) assertTrue(KeyCodec.parsePublicKey(uncompressed, x, y))
assertEquals(toHex(ECPoint.GX), toHex(x)) assertEquals(toHex(ECPoint.GX), toHex(x))
assertEquals(toHex(ECPoint.GY), toHex(y)) assertEquals(toHex(ECPoint.GY), toHex(y))
} }
@@ -326,8 +326,8 @@ class PointTest {
fun parseInvalidKey() { fun parseInvalidKey() {
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertFalse(ECPoint.parsePublicKey(ByteArray(10), x, y)) assertFalse(KeyCodec.parsePublicKey(ByteArray(10), x, y))
assertFalse(ECPoint.parsePublicKey(ByteArray(33), x, y)) // wrong prefix (0x00) assertFalse(KeyCodec.parsePublicKey(ByteArray(33), x, y)) // wrong prefix (0x00)
} }
@Test @Test
@@ -366,9 +366,9 @@ class PointTest {
assertEquals(0x03.toByte(), compressed[0]) // Odd y → 03 prefix assertEquals(0x03.toByte(), compressed[0]) // Odd y → 03 prefix
val x = LongArray(4) val x = LongArray(4)
val y = LongArray(4) val y = LongArray(4)
assertTrue(ECPoint.parsePublicKey(compressed, x, y)) assertTrue(KeyCodec.parsePublicKey(compressed, x, y))
// Round-trip: compress again should give same result // Round-trip: compress again should give same result
val recompressed = ECPoint.serializeCompressed(x, y) val recompressed = KeyCodec.serializeCompressed(x, y)
assertEquals(compressed.toList(), recompressed.toList()) assertEquals(compressed.toList(), recompressed.toList())
} }
} }