RSA解密时javax.crypto.BadPaddingException: Data must start with zero

解决方法：要在加密后产生的byte数组转成string时要在各byte之间加个标识符，我加了个空格，

然后再根据空格分隔转换回byte数组。如果不加标识符，由于byte值可能是一位到三位，无法知道某一个byte是在哪里结束。当然也可以在转成string时补0。或者转成16进制固定为两位长。

code:

public class RSATest {

public static void main(String[] args) {

try {

RSATest encrypt = new RSATest();

KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

keyPairGen.initialize(1024);

KeyPair keyPair = keyPairGen.generateKeyPair();

RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

String str = "Hello World!";

System.out.println("String will be encrypted: " + str);

byte[] e = encrypt.encrypt(publicKey, str.getBytes());

String tmp1 = encrypt.bytesToString(e);

System.out

.println("encrypted String's bytes, use

bytesToString() method convert bytes to string: " + tmp1);

String[] strArr = tmp1.split(" ");

int len = strArr.length;

byte[] clone = new byte[len];

for (int i = 0; i < len; i++) {

clone[i] = Byte.parseByte(strArr[i]);

}

System.out.println("convert to String, then back to bytes

again: " + encrypt.bytesToString(clone));

byte[] d = encrypt.decrypt(privateKey, clone);

System.out.println("decrypted String's bytes, use

bytesToString() method convert bytes to string:"

+ encrypt.bytesToString(d));

System.out.println("construct a string by decrypted

string's bytes: " + new String(d));

} catch (Exception e) {

e.printStackTrace();

}

}

protected String bytesToString(byte[] encrytpByte) {

String result = "";

for (Byte bytes : encrytpByte) {

result += bytes.toString() + " ";

}

return result;

}

protected byte[] encrypt(RSAPublicKey publicKey, byte[] obj) {

if (publicKey != null) {

try {

Cipher cipher = Cipher.getInstance("RSA");

cipher.init(Cipher.ENCRYPT_MODE, publicKey);

return cipher.doFinal(obj);

} catch (Exception e) {

e.printStackTrace();

}

}

return null;

}

protected byte[] decrypt(RSAPrivateKey privateKey, byte[] obj) {

if (privateKey != null) {

try {

Cipher cipher = Cipher.getInstance("RSA");

cipher.init(Cipher.DECRYPT_MODE, privateKey);

return cipher.doFinal(obj);

} catch (Exception e) {

e.printStackTrace();

}

}

return null;

}

}

运行结果：

String will be encrypted: Hello World!

encrypted String's bytes, use bytesToString() method convert bytes to

string: 79 62 -105 -47 -61 45 64 -11 -8 -120 30 31 37 -111 49 -30 88

-12 93 -77 3 39 -13 -18 68 -104 0 30 85 26 104 15 -126 -39 12 110 -84

68 -43 73 35 121 -20 -69 -84 85 -33 -123 -48 -68 -85 -106 41 -84 20

-17 87 -81 42 -67 -87 122 -2 37 74 27 103 112 58 -125 -87 -32 96 -56

65 -2 -103 -28 70 107 2 28 87 75 -8 -62 54 12 -7 -108 -123 120 -63 -83

13 -89 -21 58 -51 -84 66 25 103 -114 -14 110 80 58 74 95 -57 -73 -78

-46 56 -83 -72 -38 2 43 25 12 56 12 101 15 91 -37

convert to String, then back to bytes again: 79 62 -105 -47 -61 45 64

-11 -8 -120 30 31 37 -111 49 -30 88 -12 93 -77 3 39 -13 -18 68 -104 0

30 85 26 104 15 -126 -39 12 110 -84 68 -43 73 35 121 -20 -69 -84 85

-33 -123 -48 -68 -85 -106 41 -84 20 -17 87 -81 42 -67 -87 122 -2 37 74

27 103 112 58 -125 -87 -32 96 -56 65 -2 -103 -28 70 107 2 28 87 75 -8

-62 54 12 -7 -108 -123 120 -63 -83 13 -89 -21 58 -51 -84 66 25 103

-114 -14 110 80 58 74 95 -57 -73 -78 -46 56 -83 -72 -38 2 43 25 12 56

12 101 15 91 -37

decrypted String's bytes, use bytesToString() method convert bytes to

string:72 101 108 108 111 32 87 111 114 108 100 33

construct a string by decrypted string's bytes: Hello World!