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对称加密算法

常见的算法

1.DES : Data Encryption standard

2.AES : Advanced Encryption standard

自己可以指定密钥，用密钥就可以破解了

也就是 加密和解密是互逆的

底层的原理一般是操作二进制

下面是 DES加密解密算法的 API ，因为用UTF-8编码，会报错，因此必须是用 Base64编码一下

import java.security.Keyimport java.util.*import javax.crypto.Cipherimport javax.crypto.SecretKeyFactoryimport javax.crypto.spec.DESKeySpec/** * @Author  lyr * @create 2020/6/29 19:49 */fun main() {
       val util = DESCrypt()    val result = (util.encrypt("hello world"))    println(result)    println(util.decrypt((result)))}class DESCrypt {
       private val password = "12345677"    fun encrypt(yourWords: String): String {
           val cipher = Cipher.getInstance("DES")        val kf = SecretKeyFactory.getInstance("DES")        val keySpec = DESKeySpec(password.toByteArray())        val key: Key? = kf.generateSecret(keySpec)        cipher.init(Cipher.ENCRYPT_MODE, key)        val s = cipher.doFinal(yourWords.toByteArray())        return Base64.getEncoder().encodeToString(s)    }    fun decrypt(cryptograph: String): String? {
           val cipher = Cipher.getInstance("DES")        val kfactory = SecretKeyFactory.getInstance("DES")        val keySpec = DESKeySpec(password.toByteArray())        val key: Key? = kfactory.generateSecret(keySpec)        cipher.init(Cipher.DECRYPT_MODE, key)        val res = (cipher.doFinal(Base64.getDecoder().decode(cryptograph)))        return String(res)    }}

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