Fixup for #6 (native signature format detection) (#8)

* Fixup for #6

Behaviour was changed in the JNI wapper but not in Kotlin native code.

* Set version to 0.2.1-1.4-M3

build.gradle.kts

@@ -24,7 +24,7 @@ buildscript {
 
 allprojects {
     group = "fr.acinq.secp256k1"
-    version = "0.2.0-1.4-M3"
+    version = "0.2.1-1.4-M3"
 
     repositories {
         jcenter()

src/nativeMain/kotlin/fr/acinq/secp256k1/Secp256k1Native.kt

@@ -18,10 +18,10 @@ public object Secp256k1Native : Secp256k1 {
         val sig = alloc<secp256k1_ecdsa_signature>()
         val nativeBytes = toNat(input)
 
-        val result = when (input.size) {
+        val result = when {
-            64 -> secp256k1_ecdsa_signature_parse_compact(ctx, sig.ptr, nativeBytes)
+            input.size == 64 -> secp256k1_ecdsa_signature_parse_compact(ctx, sig.ptr, nativeBytes)
-            in 70..73 -> secp256k1_ecdsa_signature_parse_der(ctx, sig.ptr, nativeBytes, input.size.convert())
+            input.size < 64 -> throw Secp256k1Exception("Unknown signature format")
-            else -> throw Secp256k1Exception("Unknown signature format")
+            else -> secp256k1_ecdsa_signature_parse_der(ctx, sig.ptr, nativeBytes, input.size.convert())
         }
         result.requireSuccess("cannot parse signature (size = ${input.size} sig = ${Hex.encode(input)}")
         return sig

tests/src/commonTest/kotlin/fr/acinq/secp256k1/Secp256k1Test.kt

@@ -1,5 +1,6 @@
 package fr.acinq.secp256k1
 
+import kotlin.random.Random
 import kotlin.test.*
 
 
@@ -265,4 +266,24 @@ class Secp256k1Test {
             Hex.encode(der).toUpperCase(),
         )
     }
+
+    @Test
+    fun testFormatConversion() {
+        val random = Random.Default
+
+        fun randomBytes(length: Int): ByteArray {
+            val buffer = ByteArray(length)
+            random.nextBytes(buffer)
+            return buffer
+        }
+
+        repeat(200) {
+            val priv = randomBytes(32)
+            val pub = Secp256k1.pubkeyCreate(priv)
+            val data = randomBytes(32)
+            val sig = Secp256k1.sign(data, priv)
+            val der = Secp256k1.compact2der(sig)
+            Secp256k1.verify(der, data, pub)
+        }
+    }
 }