add README

README.md

@@ -0,0 +1,57 @@
+# Kotlin OTP
+
+This library provides various [Pseudorandom Number Generator](https://en.wikipedia.org/wiki/Pseudorandom_number_generator)
+implementations in Kotlin Multiplatform.
+
+## Features
+
+* Generate random numbers using Kotlin's Random interface.
+* Seed the PRNGs to receive predictable results.
+* Reseed the PRNGs to add entropy to the following results.
+* [HMAC DRBG](https://en.wikipedia.org/wiki/NIST_SP_800-90A#Hash_DRBG_and_HMAC_DRBG)
+* Multiplatform support
+    * JVM
+    * JavaScript
+    * Native (Linux)
+
+## Installation
+
+Add the following to your `build.gradle.kts`.
+
+```kotlin
+repositories {
+    maven("https://git.infendro.com/api/packages/Infendro/maven")
+}
+
+dependencies {
+    implementation("com.infendro:random:1.0.0")
+}
+```
+
+## Usage
+
+```kotlin
+import com.infendro.hash.SHA256
+import com.infendro.random.PRNG
+
+fun main() {
+    // create a PRNG instance
+    val rng = PRNG.HMAC(SHA256)
+
+    // seed the PRNG to receive predictable results
+    rng.seed(/* some seed */)
+    val a = rng.nextInt()
+    val b = rng.nextInt()
+    val c = rng.nextInt()
+
+    // reseed the PRNG to add entropy to the following results
+    rng.reseed(/* some random entropy */)
+    val d = rng.nextInt()
+    val e = rng.nextInt()
+    val f = rng.nextInt()
+
+    // each run:
+    // a, b, and c will be predictable
+    // d, e, and f will be random (assuming the entropy is also random)
+}
+```

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

gradlew

@@ -114,7 +114,7 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -213,7 +213,7 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
         -classpath "$CLASSPATH" \
-        org.gradle.wrapper.GradleWrapperMain \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
 # Stop when "xargs" is not available.

gradlew.bat

@@ -70,11 +70,11 @@ goto fail
 :execute
 @rem Setup the command line
 
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell

src/commonMain/kotlin/com/infendro/random/HMAC.kt

@@ -1,26 +1,30 @@
 package com.infendro.random
 
-import com.infendro.bytearray.toInt
-import com.infendro.hash.SHA256
-import com.infendro.mac.HMAC
-import kotlin.random.Random
+import com.infendro.bytearray.addAll
+import com.infendro.hash.HashFunction
 
-class HMAC internal constructor() : Random() {
+class HMAC internal constructor(
+    private val function: HashFunction,
+) : PRNG() {
     private val random = Default
-    private val hmac = HMAC(SHA256)
-    private var K: ByteArray
-    private var V: ByteArray
+    private val hmac = com.infendro.mac.HMAC(function)
+    private lateinit var K: ByteArray
+    private lateinit var V: ByteArray
 
     init {
-        K = ByteArray(32).also {
-            random.nextBytes(it)
-        }
-        V = ByteArray(32).also {
-            random.nextBytes(it)
-        }
+        val bytes = random.nextBytes(function.bytes)
+        seed(bytes)
     }
 
-    fun reseed(
+    override fun seed(
+        seed: ByteArray,
+    ) {
+        K = ByteArray(function.bytes) { 0x00 }
+        V = ByteArray(function.bytes) { 0x01 }
+        reseed(seed)
+    }
+
+    override fun reseed(
         entropy: ByteArray,
     ) {
         K = hmac.hash(K, V + byteArrayOf(0x00) + entropy)
@@ -29,18 +33,21 @@ class HMAC internal constructor() : Random() {
         V = hmac.hash(K, V)
     }
 
-    override fun nextBits(
+    override fun generate(
         count: Int,
-    ): Int {
-        if (count !in 0..32) throw Exception()
-        if (count == 0) return 0
-
-        val bytes = hmac.hash(K, V)
-        val bits = bytes.take(4).toInt() ushr (32 - count)
+    ): ByteArray {
+        val bytes = buildList {
+            while (size < count) {
+                V = hmac.hash(K, V)
+                addAll(V)
+            }
+        }
 
         K = hmac.hash(K, V + byteArrayOf(0x00))
         V = hmac.hash(K, V)
 
-        return bits
+        return bytes
+            .take(count)
+            .toByteArray()
     }
 }

src/commonMain/kotlin/com/infendro/random/PRNG.kt

@@ -1,5 +1,36 @@
 package com.infendro.random
 
-object PRNG {
-    val HMAC = HMAC()
+import com.infendro.bytearray.toInt
+import com.infendro.hash.HashFunction
+import kotlin.random.Random
+
+abstract class PRNG : Random() {
+    abstract fun seed(
+        seed: ByteArray,
+    )
+
+    abstract fun reseed(
+        entropy: ByteArray,
+    )
+
+    abstract fun generate(
+        count: Int,
+    ): ByteArray
+
+    override fun nextBits(
+        bitCount: Int,
+    ): Int {
+        if (bitCount !in 0..32) throw Exception()
+        if (bitCount == 0) return 0
+
+        return generate(4).toInt() ushr (32 - bitCount)
+    }
+
+    companion object {
+        fun HMAC(
+            function: HashFunction,
+        ): HMAC {
+            return com.infendro.random.HMAC(function)
+        }
+    }
 }