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babafeng/java-rsa-demo-RSACrypto

Created December 28, 2016 03:07
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使用java-rsa加密解密
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java-rsa-demo-RSACrypto
import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
/**
* @author babafeng
* @date : 2016年12月28日 上午11:05:06
*/
public class RSACrypto {
public static HashMap<String, Object> generateKeys() throws NoSuchAlgorithmException {
HashMap<String, Object> map = new HashMap<String, Object>();
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey pubkey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey prikey = (RSAPrivateKey) keyPair.getPrivate();
map.put("PubKey", pubkey);
map.put("PriKey", prikey);
return map;
}
public static HashMap<String, Object> generateKeys(int nbits) throws NoSuchAlgorithmException {
HashMap<String, Object> map = new HashMap<String, Object>();
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(nbits);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey pubkey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey prikey = (RSAPrivateKey) keyPair.getPrivate();
map.put("PubKey", pubkey);
map.put("PriKey", prikey);
return map;
}
public static RSAPublicKey getPublicKey(String modulus, String exponent)
throws NoSuchAlgorithmException, InvalidKeySpecException {
BigInteger mod = new BigInteger(modulus);
BigInteger exp = new BigInteger(exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(mod, exp);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
}
public static RSAPrivateKey getPrivateKey(String modulus, String exponent)
throws NoSuchAlgorithmException, InvalidKeySpecException {
BigInteger mod = new BigInteger(modulus);
BigInteger exp = new BigInteger(exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(mod, exp);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
}
public static String[] splitString(String string, int len) {
int integer = string.length() / len;
int mod = string.length() % len;
int tmp = 0;
if (mod != 0) {
tmp = 1;
}
String[] strings = new String[integer + tmp];
String str = "";
for (int i = 0; i < integer + tmp; i++) {
if (i == integer + tmp - 1 && mod != 0) {
str = string.substring(i * len, i * len + mod);
} else {
str = string.substring(i * len, i * len + len);
}
strings[i] = str;
}
return strings;
}
public static byte[][] splitArray(byte[] data, int len) {
int integer = data.length / len;
int mod = data.length % len;
int tmp = 0;
if (mod != 0) {
tmp = 1;
}
byte[][] arrays = new byte[integer + tmp][];
byte[] arr;
for (int i = 0; i < integer + tmp; i++) {
arr = new byte[len];
if (i == integer + tmp - 1 && mod != 0) {
System.arraycopy(data, i * len, arr, 0, mod);
} else {
System.arraycopy(data, i * len, arr, 0, len);
}
arrays[i] = arr;
}
return arrays;
}
public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
byte[] bcd = new byte[asc_len / 2];
int j = 0;
for (int i = 0; i < (asc_len + 1) / 2; i++) {
bcd[i] = asc_to_bcd(ascii[j++]);
bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
}
return bcd;
}
public static byte asc_to_bcd(byte asc) {
byte bcd;
if ((asc >= '0') && (asc <= '9'))
bcd = (byte) (asc - '0');
else if ((asc >= 'A') && (asc <= 'F'))
bcd = (byte) (asc - 'A' + 10);
else if ((asc >= 'a') && (asc <= 'f'))
bcd = (byte) (asc - 'a' + 10);
else
bcd = (byte) (asc - 48);
return bcd;
}
public static String bcd2Str(byte[] bytes) {
char temp[] = new char[bytes.length * 2], val;
for (int i = 0; i < bytes.length; i++) {
val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
val = (char) (bytes[i] & 0x0f);
temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
}
return new String(temp);
}
public static String encrypt(RSAPublicKey pubkey, String message) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubkey);
int key_len = pubkey.getModulus().bitLength() / 8;
String[] messages = splitString(message, key_len);
String encodes = "";
for (String s : messages) {
encodes += bcd2Str(cipher.doFinal(s.getBytes()));
}
return encodes;
}
public static String encrypt(RSAPrivateKey pubkey, String message) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubkey);
int key_len = pubkey.getModulus().bitLength() / 8;
String[] messages = splitString(message, key_len);
String encodes = "";
for (String s : messages) {
encodes += bcd2Str(cipher.doFinal(s.getBytes()));
}
return encodes;
}
public static String decrypt(RSAPrivateKey prikey, String encode) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, prikey);
int key_len = prikey.getModulus().bitLength() / 8;
byte[] bytes = encode.getBytes();
byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
String decodes = "";
byte[][] arrays = splitArray(bcd, key_len);
for (byte[] arr : arrays) {
decodes += new String(cipher.doFinal(arr));
}
return decodes;
}
public static String decrypt(RSAPublicKey prikey, String encode) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, prikey);
int key_len = prikey.getModulus().bitLength() / 8;
byte[] bytes = encode.getBytes();
byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
String decodes = "";
byte[][] arrays = splitArray(bcd, key_len);
for (byte[] arr : arrays) {
decodes += new String(cipher.doFinal(arr));
}
return decodes;
}
public static void main(String args[]) throws NoSuchAlgorithmException, InvalidKeySpecException,
InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
// 初始化RSA公钥和私钥
HashMap<String, Object> keys = generateKeys(512);
// 获得公钥和私钥
RSAPublicKey publicKey = (RSAPublicKey) keys.get("PubKey");
RSAPrivateKey privateKey = (RSAPrivateKey) keys.get("PriKey");
// 使用公钥加密
System.out.println(encrypt(publicKey, "123456789"));
// 使用私钥解密
System.out.println(decrypt(privateKey, encrypt(publicKey, "123456789")));
// 使用私钥加密
System.out.println(encrypt(privateKey, "123456789"));
// 使用公钥解密
System.out.println(decrypt(publicKey, encrypt(privateKey, "123456789")));
}
}
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