SQL-based authentication: Difference between revisions

=={{header|Kotlin}}==

{{trans|Java}}

<lang scala>// Version 1.2.41

import java.sql.Connection

import java.sql.DriverManager

import java.sql.ResultSet

import java.security.MessageDigest

import java.security.SecureRandom

import java.math.BigInteger

class UserManager {

private lateinit var dbConnection: Connection

private fun md5(message: String): String {

val hexString = StringBuilder()

val bytes = message.toByteArray()

val md = MessageDigest.getInstance("MD5")

val dig = md.digest(bytes)

for (i in 0 until dig.size) {

val hex = (0xff and dig[i].toInt()).toString(16)

if (hex.length == 1) hexString.append('0')

hexString.append(hex)

}

return hexString.toString()

}

fun connectDB(host: String, port: Int, db: String, user: String, pwd: String) {

Class.forName("com.mysql.jdbc.Driver")

dbConnection = DriverManager.getConnection(

"jdbc:mysql://$host:$port/$db", user, pwd

)

}

fun createUser(user: String, pwd: String): Boolean {

val random = SecureRandom()

val salt = BigInteger(130, random).toString(16)

val insert = "INSERT INTO users " +

"(username, pass_salt, pass_md5) " +

"VALUES (?, ?, ?)"

try {

val pstmt = dbConnection.prepareStatement(insert)

with (pstmt) {

setString(1, user)

setString(2, salt)

setString(3, md5(salt + pwd))

val rowCount = executeUpdate()

close()

if (rowCount == 0) return false

}

return true

}

catch (ex: Exception) {

return false

}

}

fun authenticateUser(user: String, pwd: String): Boolean {

val select = "SELECT pass_salt, pass_md5 FROM users WHERE username = ?"

lateinit var res: ResultSet

try {

val pstmt = dbConnection.prepareStatement(select)

with (pstmt) {

setString(1, user)

res = executeQuery()

res.next() // assuming that username is unique

val passSalt = res.getString(1)

val passMD5 = res.getString(2)

close()

return passMD5 == md5(passSalt + pwd)

}

}

catch (ex: Exception) {

return false

}

finally {

if (!res.isClosed) res.close()

}

}

fun closeConnection() {

if (!dbConnection.isClosed) dbConnection.close()

}

}

fun main(args: Array<String>) {

val um = UserManager()

with (um) {

try {

connectDB("localhost", 3306, "test", "root", "admin")

if (createUser("johndoe", "test")) println("User created")

if (authenticateUser("johndoe", "test")) {

println("User authenticated")

}

}

catch(ex: Exception) {

ex.printStackTrace()

}

finally {

closeConnection()

}

}

}</lang>