从RSA编码的AES密钥生成AES密钥
Posted
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了从RSA编码的AES密钥生成AES密钥相关的知识,希望对你有一定的参考价值。
我想要做的是使用AES加密字符串,使用RSA加密AES密钥getEncoded()值,然后解密该AES getEncoded()值,以便获取我的原始字符串。公钥是从用户证书加载的,私钥是从文件加载的。代码如下。
public class Main {
public static void main(String[] args) throws Exception {
String myString = "My Message";
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(128);
SecretKey secretKey = keyGenerator.generateKey();
byte[] initializationVector = new byte[128 / 8];//16
SecureRandom prng = new SecureRandom();
prng.nextBytes(initializationVector);
Cipher AESCipherForEncryption = Cipher.getInstance("AES/CBC/PKCS5PADDING");
AESCipherForEncryption.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(initializationVector));
byte[] byteVersionOfMyMessage = myString.getBytes();
byte[] byteVersionOfCipherText = AESCipherForEncryption.doFinal(byteVersionOfMyMessage);
String cipherText = new BASE64Encoder().encode(byteVersionOfCipherText);
InputStream in1 = new FileInputStream("user.crt");
CertificateFactory cf1 = CertificateFactory.getInstance("X509");
Certificate c1 = cf1.generateCertificate(in1);
X509Certificate toSendcert = (X509Certificate) c1;
PublicKey publicKey = toSendcert.getPublicKey();
String cipherTextRSA = encryptRSA(publicKey, new String(secretKey.getEncoded()));
String decypheredRSA = decryptRSA(getPrivateKey("user.pk8", "RSA"), cipherTextRSA);
System.out.println(cipherTextRSA);
System.out.println(decypheredRSA);
SecretKey originalKey = new SecretKeySpec(new String(decypheredRSA.getBytes("UTF-8")).getBytes(), 0, new String(decypheredRSA.getBytes("UTF-8")).getBytes().length, "AES");
Cipher AESCipherForDecryption = Cipher.getInstance("AES/CBC/PKCS5PADDING");
AESCipherForDecryption.init(Cipher.DECRYPT_MODE, originalKey, new IvParameterSpec(initializationVector));
byte[] byteVersionOfDecriptedText = AESCipherForDecryption.doFinal(new BASE64Decoder().decodeBuffer(cipherText));
String decMessage = new String(byteVersionOfDecriptedText);
System.out.println(decMessage);
}
public static String encryptRSA(PublicKey pubKey, String message) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
Base64.Encoder encoder = Base64.getEncoder();
String encryptedString = encoder.encodeToString(cipher.doFinal(message.getBytes("UTF-8")));
return encryptedString;
}
public static PrivateKey getPrivateKey(String filename, String algorithm) throws Exception {
File f = new File(filename);
FileInputStream fis = new FileInputStream(f);
DataInputStream dis = new DataInputStream(fis);
byte[] keyBytes = new byte[(int) f.length()];
dis.readFully(keyBytes);
dis.close();
String temp = new String(keyBytes);
String privKeyPEM = temp.replace("-----BEGIN PRIVATE KEY-----", "");
privKeyPEM = privKeyPEM.replace("-----END PRIVATE KEY-----", "");
privKeyPEM = privKeyPEM.replace("
", "");
byte[] decoded = Base64.getDecoder().decode(privKeyPEM);
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
KeyFactory kf = KeyFactory.getInstance(algorithm);
return kf.generatePrivate(spec);
}
public static String decryptRSA(PrivateKey prKey, String encrypted) throws Exception {
Base64.Decoder decoder = Base64.getDecoder();
byte[] input = decoder.decode(encrypted);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, prKey);
return new String(cipher.doFinal(input));
}
我一直得到的错误是:
Exception in thread "main" java.security.InvalidKeyException: Invalid AES key length: 28 bytes
at com.sun.crypto.provider.AESCipher.engineGetKeySize(AESCipher.java:509)
at javax.crypto.Cipher.passCryptoPermCheck(Cipher.java:1067)
at javax.crypto.Cipher.checkCryptoPerm(Cipher.java:1038)
at javax.crypto.Cipher.implInit(Cipher.java:805)
at javax.crypto.Cipher.chooseProvider(Cipher.java:864)
at javax.crypto.Cipher.init(Cipher.java:1396)
at javax.crypto.Cipher.init(Cipher.java:1327)
at com.company.Main.main(Main.java:79)
如果我不加密和解密secretKey.getEncoded()
值,只使用没有RSA的AES它可以正常工作。如果我只使用公钥加密一些字符串,并使用私有密码解密它也可以使用RSA。我的问题是:“我如何使用RSA正确加密和解密secretKey.getEncoded()
值,以便我可以正确加密和解密myString
?”。
答案
new String(secretKey.getEncoded())
这不起作用,因为AES密钥包含随机字节,并不是每个字节都是字符代表。 Java中标准字符串转换的问题在于它丢弃了未知字符和字节,而不是在编码/解码期间生成异常。
RSA对字节进行操作,您不应将密钥转换为字符串,然后再将其转换回字节,因为转换可能是有损的(例如,丢弃32个字节中的4个)。
或者 - 甚至可能更好 - 你可能想尝试密码的包装模式。这应该与那里的一些硬件解决方案兼容。在这种情况下,你甚至不必打电话给getEncoded
。
OAEP加密和经过身份验证的加密模式(如GCM)应优先于PKCS#1填充(Sun提供商的默认设置)和CBC模式加密。
以上是关于从RSA编码的AES密钥生成AES密钥的主要内容,如果未能解决你的问题,请参考以下文章