AES 256 Kotlin.kt

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import java.security.SecureRandom
import javax.crypto.Cipher
import javax.crypto.KeyGenerator
import javax.crypto.SecretKey
import javax.crypto.spec.IvParameterSpec

fun encrypt(plainText: String, key: SecretKey): Pair<ByteArray, ByteArray> {
    val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    val iv = ByteArray(16)
    val random = SecureRandom()
    random.nextBytes(iv)
    cipher.init(Cipher.ENCRYPT_MODE, key, IvParameterSpec(iv))
    val encrypted = cipher.doFinal(plainText.toByteArray(Charsets.UTF_8))
    return Pair(iv, encrypted)
}

fun decrypt(iv: ByteArray, encrypted: ByteArray, key: SecretKey): String {
    val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    cipher.init(Cipher.DECRYPT_MODE, key, IvParameterSpec(iv))
    val decrypted = cipher.doFinal(encrypted)
    return String(decrypted, Charsets.UTF_8)
}

fun main() {
    val keyGenerator = KeyGenerator.getInstance("AES")
    keyGenerator.init(256)
    val key = keyGenerator.generateKey()

    val plainText = "Hello, World!"
    val (iv, encrypted) = encrypt(plainText, key)

    val decrypted = decrypt(iv, encrypted, key)

    println("Original message: $plainText")
    println("Encrypted message: ${String(encrypted, Charsets.UTF_8)}")
    println("Decrypted message: $decrypted")
}