[암호화] AES 인코딩, 디코딩 (AES/CBC/PKCS5PADDING/Hex) - Kotlin

 

/* 인코딩, 디코딩 */

CryptoConverter.kt

import org.springframework.boot.context.properties.ConfigurationProperties
import org.springframework.stereotype.Component
import java.util.*
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
import javax.persistence.AttributeConverter
import javax.persistence.Convert

@Convert
class CryptoConverter(
    private val aes256Config: AES256Config
)  : AttributeConverter<String, String> {

    private val key = aes256Config.key
    private val iv = aes256Config.iv
    private val secretKeySpec = SecretKeySpec(key!!.toByteArray(), "AES")
    private val ivParameterSpec = IvParameterSpec(iv!!.toByteArray())

    // 인코딩
    override fun convertToDatabaseColumn(payload: String): String? {
        val cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING")
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec)
        val encrypted = cipher.doFinal(payload.toByteArray(charset("UTF-8")))

        return byteArrayToHex(encrypted)
    }

    // 디코딩
    override fun convertToEntityAttribute(payload: String): String {
        val bytesOfPayload = Base64.getDecoder().decode(payload)
        val cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING")
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec)

        val originMessage = cipher.doFinal(hexToByteArray(payload))

        return String(originMessage)
    }

    // 헥사 -> 바이트
    fun hexToByteArray(hex: String?): ByteArray? {
        if (hex == null || hex.isEmpty()) {
            return null
        }
        val ba = ByteArray(hex.length / 2)
        for (i in ba.indices) {
            ba[i] = hex.substring(2 * i, 2 * i + 2).toInt(16).toByte()
        }
        return ba
    }

    // 바이트 -> 헥사
    fun byteArrayToHex(ba: ByteArray?): String? {
        if (ba == null || ba.isEmpty()) {
            return null
        }
        val sb = StringBuffer(ba.size * 2)
        var hexNumber: String
        for (x in ba.indices) {
            hexNumber = "0" + Integer.toHexString(0xff and ba[x].toInt())
            sb.append(hexNumber.substring(hexNumber.length - 2))
        }
        return sb.toString()
    }

    // application.yml 에서 key, iv 값 가져오기
    @Component
    @ConfigurationProperties(prefix = "aes256")
    data class AES256Config(
        var key: String?,
        var iv : String?
    )
}

application.yml

aes256:
  key: "ghj76ytrf12345567tyuijhgfre8990098765435tg212346789hgf"
  iv: "gh567cfvbn456iol"

/* 테스트 */

import com.test.CryptoConverter
import org.junit.jupiter.api.Test
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.context.properties.EnableConfigurationProperties
import org.springframework.boot.test.context.SpringBootTest
import org.springframework.test.context.TestConstructor
import org.springframework.test.context.TestPropertySource

@TestConstructor(autowireMode = TestConstructor.AutowireMode.ALL)
@EnableConfigurationProperties(CryptoConverter.AES256Config::class)
@TestPropertySource("classpath:application.yml")
@SpringBootTest(classes = [CryptoConverter::class])
class CryptoTest2 @Autowired constructor(
    private val cryptoConverter: CryptoConverter,
    val aeS256Config: CryptoConverter.AES256Config
){

    @Test
    fun `인코딩테스트`() {
        println(aeS256Config.key)
        println(aeS256Config.iv)
        println(cryptoConverter.convertToDatabaseColumn("1234123412341234"))
    }

    @Test
    fun `디코딩테스트`() {
        println(cryptoConverter.convertToEntityAttribute("7faf598710b84257cbb6f6fca720ef4fb8be41640ab24df86ee152c8e97e1918"))
    }
}