Check arguments passed to secp256k1 methods (#94)

* Check arguments passed to secp256k1 methods

Illegal arguments will trigger an internal callback that prints to stderr and calls abort.
We already check arguments in our JNI and kotlin native code but had missed 2 checks (recid in ecdsaRecover, empty arrays in pubkeyCombine).

* Implement the same "tweak" checks in the native code and JNI code

The native code was missing checks on the "tweak" size (which must be 32 bytes)

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

@@ -352,6 +352,38 @@ class Secp256k1Test {
         }
     }
 
+    @Test
+    fun testInvalidArguments() {
+        assertFails {
+            Secp256k1.pubkeyCreate(ByteArray(32))
+        }
+        assertFails {
+            Secp256k1.pubkeyCreate(Hex.decode("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"))
+        }
+        assertFails {
+            Secp256k1.pubkeyParse(ByteArray(33))
+        }
+        assertFails {
+            Secp256k1.pubkeyParse(Hex.decode("03ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"))
+        }
+        assertFails {
+            Secp256k1.pubKeyCombine(arrayOf())
+        }
+        assertFails {
+            Secp256k1.pubKeyCombine(arrayOf(ByteArray(0)))
+        }
+        assertFails {
+            Secp256k1.signSchnorr(ByteArray(0), Hex.decode("0101010101010101010101010101010101010101010101010101010101010101"), null)
+        }
+        assertFails {
+            Secp256k1.ecdsaRecover(
+                Hex.decode("01010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101"),
+                Hex.decode("0202020202020202020202020202020202020202020202020202020202020202"),
+                -1
+            )
+        }
+    }
+
     @Test
     fun fuzzEcdsaSignVerify() {
         val random = Random.Default