Completed random support functions

multiplatform-crypto-libsodium-bindings/src/jsMain/kotlin/com/ionspin/kotlin/crypto/JsSodiumInterface.kt

@@ -207,9 +207,18 @@ interface JsSodiumInterface {
     fun from_hex(data : String): Uint8Array
     fun from_string(data : String): Uint8Array
 
+    //  ---- > ---- Random ---- < -----
+
+    fun randombytes_buf(length: UInt) : Uint8Array
+    fun randombytes_buf_deterministic(length: UInt, seed : Uint8Array) : Uint8Array
+    fun randombytes_random() : UInt
+    fun randombytes_uniform(upper_bound: UInt) : UInt
+
     // ---- Utils end ----
 
 
 
 
+
+
 }

multiplatform-crypto-libsodium-bindings/src/jsMain/kotlin/com/ionspin/kotlin/crypto/util/LibsodiumRandom.kt

@@ -0,0 +1,48 @@
+package com.ionspin.kotlin.crypto.util
+
+import com.ionspin.kotlin.crypto.getSodium
+import ext.libsodium.com.ionspin.kotlin.crypto.toUByteArray
+import ext.libsodium.com.ionspin.kotlin.crypto.toUInt8Array
+
+/**
+ * Created by Ugljesa Jovanovic
+ * ugljesa.jovanovic@ionspin.com
+ * on 27-Sep-2020
+ */
+actual object LibsodiumRandom {
+    /**
+     * The randombytes_buf() function fills size bytes starting at buf with an unpredictable sequence of bytes.
+     */
+    actual fun buf(size: Int): UByteArray {
+        return getSodium().randombytes_buf(size).toUByteArray()
+    }
+
+    /**
+     * The randombytes_buf_deterministic function stores size bytes into buf indistinguishable from random bytes without knowing seed.
+     * For a given seed, this function will always output the same sequence. size can be up to 2^31 (~8GB) because we use kotlin arrays
+     * and they are limited by Int primitive type
+     * seed is randombytes_SEEDBYTES bytes long.
+     * This function is mainly useful for writing tests, and was introduced in libsodium 1.0.12. Under the hood, it uses the ChaCha20 stream cipher.
+     *
+     */
+    actual fun bufDeterministic(size: Int, seed: UByteArray): UByteArray {
+        return getSodium().randombytes_buf_deterministic(size.toUInt(), seed.toUInt8Array()).toUByteArray()
+    }
+
+    /**
+     * The randombytes_random() function returns an unpredictable value between 0 and 0xffffffff (included).
+     */
+    actual fun random(): UInt {
+        return getSodium().randombytes_random()
+    }
+
+    /**
+     * The randombytes_uniform() function returns an unpredictable value between 0 and upper_bound (excluded). Unlike r
+     * andombytes_random() % upper_bound, it guarantees a uniform distribution of the possible output values even when
+     * upper_bound is not a power of 2. Note that an upper_bound < 2 leaves only a single element to be chosen, namely 0
+     */
+    actual fun uniform(upperBound: UInt): UInt {
+        return getSodium().randombytes_uniform(upperBound)
+    }
+
+}