Question

我有一个硬编码密钥，我希望在将其存储到SharedPreferences之前对其进行加密。这是我到目前为止的代码：

public class TokenEncryptor {

    private final static String TOKEN_KEY = "91a29fa7w46d8x41";

    public static String encrypt(String plain) {
        try {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
            SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
            cipher.init(Cipher.ENCRYPT_MODE, newKey, ivSpec);
            return new String(cipher.doFinal(plain.getBytes()));
        } catch (Exception e) {
            Ln.e(e);
            return null;
        }
    }

    public static String decrypt(String encoded) {
        try {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
            SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
            cipher.init(Cipher.DECRYPT_MODE, newKey, ivSpec);
            return new String(cipher.doFinal(encoded.getBytes()));
        } catch (Exception e) {
            Ln.e(e);
            return null;
        }
    }
}

似乎是在decrypt方法结束时捕获异常：

javax.crypto.IllegalBlockSizeException: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length

有人能指出我正确的方向吗？我有一种感觉，我做错了实例化IvParameterSpec。

Answer 1

使用AES加密字符串时，会得到一个字节数组。尝试将这些字节直接转换为字符串（new String(cipher.doFinal(plaintextBytes))）将导致各种问题。如果您要求加密方法的输出为字符串，请使用Base64而不是尝试直接转换。在解密方法中，在解密字节数组之前，将Base64字符串转换回字节数组。

此外，请勿使用getBytes()，因为输出取决于系统默认值。使用getBytes("utf-8")或其他。这消除了歧义。

Answer 2

万一有人对此感兴趣（或者感觉懒得做研究），这里是AES-256加密和解密的结果代码，我把它放在一起，在接受的答案和评论的帮助下：< / p>

public class TokenEncryptor {

    private final static String TOKEN_KEY = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw";

    public static String encrypt(String plain) {
        try {
            byte[] iv = new byte[16];
            new SecureRandom().nextBytes(iv);
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
            byte[] cipherText = cipher.doFinal(plain.getBytes("utf-8"));
            byte[] ivAndCipherText = getCombinedArray(iv, cipherText);
            return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP);
        } catch (Exception e) {
            Ln.e(e);
            return null;
        }
    }

    public static String decrypt(String encoded) {
        try {
            byte[] ivAndCipherText = Base64.decode(encoded, Base64.NO_WRAP);
            byte[] iv = Arrays.copyOfRange(ivAndCipherText, 0, 16);
            byte[] cipherText = Arrays.copyOfRange(ivAndCipherText, 16, ivAndCipherText.length);

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
            return new String(cipher.doFinal(cipherText), "utf-8");
        } catch (Exception e) {
            Ln.e(e);
            return null;
        }
    }

    private static byte[] getCombinedArray(byte[] one, byte[] two) {
        byte[] combined = new byte[one.length + two.length];
        for (int i = 0; i < combined.length; ++i) {
            combined[i] = i < one.length ? one[i] : two[i - one.length];
        }
        return combined;
    }

}

Answer 3

@Oleksiy答案的科特琳版。

<script src="https://gist.github.com/kasim1011/a5a9644a60c33a4df3c29f4b34cf93a4.js"></script>

import android.util.Base64
import java.util.*
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec

private const val algorithm = "AES"
private const val tokenKey = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw"
private const val padding = "AES/CBC/PKCS5Padding"
private const val ivSize = 16

fun String.encryptAES(): String {
    val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
    val secretKey = SecretKeySpec(tokenBytes, algorithm)

    val ivByteArray = ByteArray(ivSize)
    val iv = IvParameterSpec(ivByteArray)

    val cipher = Cipher.getInstance(padding)
    cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv)

    val cipherText = cipher.doFinal(toByteArray(Charsets.UTF_8))
    val ivAndCipherText = getCombinedArray(ivByteArray, cipherText)

    return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP)
}

fun String.decryptAES(): String {
    val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
    val secretKey = SecretKeySpec(tokenBytes, algorithm)

    val ivAndCipherText = Base64.decode(this, Base64.NO_WRAP)
    val cipherText = Arrays.copyOfRange(ivAndCipherText, ivSize, ivAndCipherText.size)

    val ivByteArray = Arrays.copyOfRange(ivAndCipherText, 0, ivSize)
    val iv = IvParameterSpec(ivByteArray)

    val cipher = Cipher.getInstance(padding)
    cipher.init(Cipher.DECRYPT_MODE, secretKey, iv)

    return cipher.doFinal(cipherText).toString(Charsets.UTF_8)
}

private fun getCombinedArray(one: ByteArray, two: ByteArray): ByteArray {
    val combined = ByteArray(one.size + two.size)
    for (i in combined.indices) {
        combined[i] = if (i < one.size) one[i] else two[i - one.size]
    }
    return combined
}

尝试使用AES加密和解密字符串时出现IllegalBlockSizeException

3 个答案: