Add initial public key transformer

bundler/src/main/java/dev/openrs2/bundler/transform/PublicKeyTransformer.kt

@@ -0,0 +1,57 @@
+package dev.openrs2.bundler.transform
+
+import com.github.michaelbull.logging.InlineLogger
+import dev.openrs2.asm.classpath.ClassPath
+import dev.openrs2.asm.classpath.Library
+import dev.openrs2.asm.transform.Transformer
+import org.bouncycastle.crypto.params.RSAKeyParameters
+import org.objectweb.asm.tree.ClassNode
+import org.objectweb.asm.tree.LdcInsnNode
+import org.objectweb.asm.tree.MethodNode
+
+class PublicKeyTransformer(private val key: RSAKeyParameters) : Transformer() {
+    private var exponents = 0
+    private var moduli = 0
+
+    init {
+        require(!key.isPrivate)
+    }
+
+    override fun preTransform(classPath: ClassPath) {
+        exponents = 0
+        moduli = 0
+    }
+
+    override fun transformCode(classPath: ClassPath, library: Library, clazz: ClassNode, method: MethodNode): Boolean {
+        for (insn in method.instructions) {
+            if (insn !is LdcInsnNode) {
+                continue
+            }
+
+            when (insn.cst) {
+                JAGEX_EXPONENT -> {
+                    insn.cst = key.exponent.toString()
+                    exponents++
+                }
+                JAGEX_MODULUS -> {
+                    insn.cst = key.modulus.toString()
+                    moduli++
+                }
+            }
+        }
+
+        return false
+    }
+
+    override fun postTransform(classPath: ClassPath) {
+        logger.info { "Replaced $exponents exponents and $moduli moduli" }
+    }
+
+    companion object {
+        private val logger = InlineLogger()
+        private const val JAGEX_EXPONENT =
+            "58778699976184461502525193738213253649000149147835990136706041084440742975821"
+        private const val JAGEX_MODULUS = "71629005252297980327618167912305272963293132912323242902378492635012082079" +
+            "72894053929065636522363163621000728841182238772712427862772219676577293600221789"
+    }
+}