Change hash function

hybrid-crypto/src/main/java/me/pisal/hybridcrypto/aes/AESCipher.kt

@@ -13,8 +13,20 @@ import javax.crypto.spec.PBEKeySpec
 import javax.crypto.spec.SecretKeySpec
 
 class AESCipher(
+    /**
+     * Recommended by OWASP: 16 (bytes)
+     */
     private val aesKeySizeInBytes: Int,
+
+    /**
+     * Recommended by OWASP: "AES/CBC/PKCS7Padding"
+     */
     private val aesMode: String = "AES/CBC/PKCS7Padding",
+
+    /**
+     * Recommended: 100 good an equilibrium between robustness and performance.
+     * The bigger, the more secure, but slower at the same time.
+     */
     private val keyIterationCount: Int = 100
 ) {
 

hybrid-crypto/src/main/java/me/pisal/hybridcrypto/hybrid/HybridCrypto.kt

@@ -6,7 +6,6 @@ import me.pisal.hybridcrypto.rsa.RSACipher
 import java.io.Serializable
 import java.security.MessageDigest
 import java.security.SecureRandom
-import kotlin.experimental.and
 
 /**
  * A combined crypto mechanism of
@@ -67,15 +66,24 @@ class HybridCrypto private constructor() {
     }
 
     private fun sha512(message: String): String {
+        val bytes = message.toByteArray()
         val md = MessageDigest.getInstance("SHA-512")
-        val digest = md.digest(message.toByteArray())
-        val builder = StringBuilder()
-        for (i in digest.indices) {
-            builder.append(((digest[i] and 0xff.toByte()) + 0x100)
-                .toString(16)
-                .substring(1))
-        }
-        return builder.toString()
+        val digest = md.digest(bytes)
+        return digest.fold("") { str, it -> str + "%02x".format(it) }
+
+//        val bytes = input.toByteArray()
+//        val md = MessageDigest.getInstance("SHA-512")
+//        val digest = md.digest(bytes)
+//        return digest.fold("") { str, it -> str + "%02x".format(it) }
+//        val md = MessageDigest.getInstance("SHA-512")
+//        val digest = md.digest(message.toByteArray())
+//        val builder = StringBuilder()
+//        for (i in digest.indices) {
+//            builder.append(((digest[i] and 0xff.toByte()) + 0x100)
+//                .toString(16)
+//                .substring(1))
+//        }
+//        return builder.toString()
     }
 
     data class Configuration(