further optimize HMAC-DRBG

src/commonMain/kotlin/com/infendro/random/csprng/HMAC-DRBG.kt

@@ -6,7 +6,7 @@ import com.infendro.mac.HMAC
 import com.infendro.random.CSPRNG
 import kotlin.properties.Delegates.notNull
 
-class `HMAC-DRBG` internal constructor(
+class `HMAC-DRBG`(
     private val function: HashFunction,
 ) : CSPRNG() {
     private val hmac = HMAC(function)
@@ -14,6 +14,8 @@ class `HMAC-DRBG` internal constructor(
     private var k: ByteArray by notNull()
     private var v: ByteArray by notNull()
 
+    private val buffer = ByteArray(function.bytes + 1)
+
     override fun seed(seed: ByteArray) {
         k = ByteArray(function.bytes) { 0x00 }
         v = ByteArray(function.bytes) { 0x01 }
@@ -21,17 +23,28 @@ class `HMAC-DRBG` internal constructor(
     }
 
     override fun reseed(entropy: ByteArray) {
-        k = hmac.hash(k, v + byteArrayOf(0x00) + entropy)
-        v = hmac.hash(k, v)
-        k = hmac.hash(k, v + byteArrayOf(0x01) + entropy)
-        v = hmac.hash(k, v)
+        val value = ByteArray(v.size + 1 + entropy.size)
+
+        v.copyInto(value)
+        value[v.size] = 0x00
+        entropy.copyInto(value, v.size + 1)
+        hmac.hashInto(k, value, k)
+        hmac.hashInto(k, v, v)
+
+        value[v.size] = 0x01
+        hmac.hashInto(k, value, k)
+        hmac.hashInto(k, v, v)
     }
 
     override fun generate(): Int {
-        v = hmac.hash(k, v)
+        hmac.hashInto(k, v, v)
         val result = v.toInt()
-        k = hmac.hash(k, v + byteArrayOf(0x00))
-        v = hmac.hash(k, v)
+
+        v.copyInto(buffer)
+        buffer[v.size] = 0x00
+        hmac.hashInto(k, buffer, k)
+        hmac.hashInto(k, v, v)
+
         return result
     }
 }

src/commonMain/kotlin/com/infendro/random/prng/LCG.kt

@@ -5,7 +5,7 @@ import com.infendro.hash.sha2.`SHA-256`
 import com.infendro.random.PRNG
 import kotlin.properties.Delegates.notNull
 
-class LCG internal constructor() : PRNG() {
+class LCG : PRNG() {
     private val a: Long = 25214903917L
     private val c: Long = 11L
     private val mask: Long = (1L shl 48) - 1