歐尼斯特

import java.math.BigInteger
import java.security.KeyFactory
import java.security.PublicKey
import java.security.spec.RSAPublicKeySpec
import javax.crypto.Cipher


object RSAEncryptUtil {
   private var n: BigInteger? = null
   private var e: BigInteger? = null
   private var result: String? = null

   /**
    * RSA加密
    *
    * @param password 內容
    */
   fun RSAEncrypt(password: ByteArray): String? {
       if (password.isEmpty()) {
           return null
       }
       val keySpec = RSAPublicKeySpec(n, e)
       val kf: KeyFactory = KeyFactory.getInstance("RSA")
       val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")
       val keyPublic: PublicKey = kf.generatePublic(keySpec)

       cipher.init(Cipher.ENCRYPT_MODE, keyPublic)
       val encryptData: ByteArray = cipher.doFinal(password)
       return encryptData.toHexString()
   }

   fun setPublic(keyModule: String?, keyExponent: String?) {
       if (keyModule == null && keyExponent == null) {
           n = null
           e = null
           result = null
           return
       }
       n = BigInteger(keyModule, 16)
       e = BigInteger(keyExponent, 16)
   }
}

其中toHexString

為Kotlin的extension