前言
最近項目中需要利用RSA進行加解密，RSA是目前最流行的，也是最為安全的一種加密方式，RSA利用公鑰和私鑰來作為密鑰，可以私鑰加密公鑰解密，也可以私鑰解密公鑰加密。
坑點:
當伺服器端給到我私鑰的時候（利用openssL生成），我無論怎麼去解析私鑰，都會抛出私鑰非法，後來發現在生成私鑰的時候并沒有轉換成PCK8标準的，由于背景是php，php中是不需要轉換的，是以在這點上花了些時間踩坑。
RSATools.java工具類:
public class RSATools {
//密鑰對
static String privateKeyWubo ="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";
/**
* 私鑰
*/
private RSAPrivateKey privateKey;
/**
* 公鑰
*/
private RSAPublicKey publicKey;
/**
* 位元組資料轉字元串專用集合
*/
private static final char[] HEX_CHAR= {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* 擷取私鑰
* @return 目前的私鑰對象
*/
public RSAPrivateKey getPrivateKey() {
return privateKey;
}
/**
* 擷取公鑰
* @return 目前的公鑰對象
*/
public RSAPublicKey getPublicKey() {
return publicKey;
}
/**
* 随機生成密鑰對
*/
public void genKeyPair(){
KeyPairGenerator keyPairGen= null;
try {
keyPairGen= KeyPairGenerator.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
keyPairGen.initialize(, new SecureRandom());
KeyPair keyPair= keyPairGen.generateKeyPair();
this.privateKey= (RSAPrivateKey) keyPair.getPrivate();
this.publicKey= (RSAPublicKey) keyPair.getPublic();
}
/**
* 從檔案中輸入流中加載公鑰
* @param in 公鑰輸入流
* @throws Exception 加載公鑰時産生的異常
*/
public void loadPublicKey(InputStream in) throws Exception{
try {
BufferedReader br= new BufferedReader(new InputStreamReader(in));
String readLine= null;
StringBuilder sb= new StringBuilder();
while((readLine= br.readLine())!=null){
if(readLine.charAt()=='-'){
continue;
}else{
sb.append(readLine);
sb.append('\r');
}
}
loadPublicKey(sb.toString());
} catch (IOException e) {
throw new Exception("公鑰資料流讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("公鑰輸入流為空");
}
}
/**
* 從字元串中加載公鑰
* @param publicKeyStr 公鑰資料字元串
* @throws Exception 加載公鑰時産生的異常
*/
public void loadPublicKey(String publicKeyStr) throws Exception{
try {
BASE64Decoder base64Decoder= new BASE64Decoder();
byte[] buffer= base64Decoder.decodeBuffer(publicKeyStr);
KeyFactory keyFactory= KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec= new X509EncodedKeySpec(buffer);
this.publicKey= (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公鑰非法");
} catch (IOException e) {
throw new Exception("公鑰資料内容讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("公鑰資料為空");
}
}
/**
* 從檔案中加載私鑰
* @param keyFileName 私鑰檔案名
* @return 是否成功
* @throws Exception
*/
public void loadPrivateKey(InputStream in) throws Exception{
try {
BufferedReader br= new BufferedReader(new InputStreamReader(in));
String readLine= null;
StringBuilder sb= new StringBuilder();
while((readLine= br.readLine())!=null){
if(readLine.charAt()=='-'){
continue;
}else{
sb.append(readLine);
sb.append('\r');
}
}
loadPrivateKey(sb.toString());
} catch (IOException e) {
throw new Exception("私鑰資料讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("私鑰輸入流為空");
}
}
public void loadPrivateKey(String privateKeyStr) throws Exception{
try {
BASE64Decoder base64Decoder= new BASE64Decoder();
byte[] buffer= base64Decoder.decodeBuffer(privateKeyStr);
PKCS8EncodedKeySpec keySpec= new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory= KeyFactory.getInstance("RSA");
this.privateKey= (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("私鑰非法");
} catch (IOException e) {
throw new Exception("私鑰資料内容讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("私鑰資料為空");
}
}
/**
* 私鑰加密過程
* @param rsaPrivateKey 私鑰
* @param plainTextData 明文資料
* @return
* @throws Exception 加密過程中的異常資訊
*/
public byte[] encrypt(RSAPrivateKey rsaPrivateKey,byte[] plainTextData)throws Exception{
if (privateKey== null){
try {
throw new Exception("解密私鑰為空, 請設定");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] result = cipher.doFinal(plainTextData);
return result;
} catch (InvalidKeyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此加密算法");
} catch (InvalidKeySpecException e) {
throw new Exception("加密公鑰非法,請檢查");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (IllegalBlockSizeException e) {
throw new Exception("明文長度非法");
} catch (BadPaddingException e) {
throw new Exception("明文資料已損壞");
}
return null;
}
/**
* 解密過程
* @param rsaPublicKey 公鑰
* @param cipherData 密文資料
* @return 明文
* @throws Exception 解密過程中的異常資訊
*/
//公鑰解密
public String decrypt(RSAPublicKey rsaPublicKey,byte[] cipherData) throws Exception{
try {
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, publicKey);
byte[] result = cipher.doFinal(cipherData);
return new String(result);
} catch (InvalidKeyException e) {
throw new Exception("解密私鑰非法,請檢查");
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此解密算法");
} catch (InvalidKeySpecException e) {
throw new Exception("解密私鑰非法,請檢查");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (IllegalBlockSizeException e) {
throw new Exception("密文長度非法");
} catch (BadPaddingException e) {
throw new Exception("密文資料已損壞");
}
}
/**
* 加密過程
* @param publicKey 公鑰
* @param plainTextData 明文資料
* @return
* @throws Exception 加密過程中的異常資訊
*/
public byte[] gonyaoEncrypt(RSAPublicKey publicKey, byte[] plainTextData) throws Exception{
if(publicKey== null){
throw new Exception("加密公鑰為空, 請設定");
}
Cipher cipher= null;
try {
cipher= Cipher.getInstance("RSA/ECB/PKCS1Padding", new BouncyCastleProvider());
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] output= cipher.doFinal(plainTextData);
return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此加密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
}catch (InvalidKeyException e) {
throw new Exception("加密公鑰非法,請檢查");
} catch (IllegalBlockSizeException e) {
throw new Exception("明文長度非法");
} catch (BadPaddingException e) {
throw new Exception("明文資料已損壞");
}
}
/**
* 解密過程
* @param privateKey 私鑰
* @param cipherData 密文資料
* @return 明文
* @throws Exception 解密過程中的異常資訊
*/
public byte[] siyaoDecrypt(RSAPrivateKey privateKey, byte[] cipherData) throws Exception{
if (privateKey== null){
throw new Exception("解密私鑰為空, 請設定");
}
Cipher cipher= null;
try {
cipher= Cipher.getInstance("RSA/ECB/PKCS1Padding", new BouncyCastleProvider());
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] output= cipher.doFinal(cipherData);
return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此解密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
}catch (InvalidKeyException e) {
throw new Exception("解密私鑰非法,請檢查");
} catch (IllegalBlockSizeException e) {
throw new Exception("密文長度非法");
} catch (BadPaddingException e) {
throw new Exception("密文資料已損壞");
}
}
/**
* 位元組資料轉十六進制字元串
* @param data 輸入資料
* @return 十六進制内容
*/
public static String byteArrayToString(byte[] data){
StringBuilder stringBuilder= new StringBuilder();
for (int i=; i<data.length; i++){
//取出位元組的高四位 作為索引得到相應的十六進制辨別符 注意無符号右移
stringBuilder.append(HEX_CHAR[(data[i] & )>>> ]);
//取出位元組的低四位 作為索引得到相應的十六進制辨別符
stringBuilder.append(HEX_CHAR[(data[i] & )]);
if (i<data.length-){
stringBuilder.append(' ');
}
}
return stringBuilder.toString();
}
}
測試函數:
public static void main(String[] args){
RSATools rsaEncrypt= new RSATools();
//加載公鑰
try {
// rsaEncrypt.loadPublicKey(new FileInputStream("rsa_public_key.pem"));
rsaEncrypt.loadPublicKey(publicKeyWubo);
System.out.println("加載公鑰成功");
} catch (Exception e) {
System.err.println(e.getMessage());
System.err.println("加載公鑰失敗");
}
//加載私鑰
try {
// rsaEncrypt.loadPrivateKey(new FileInputStream("rsa_private_key.pem"));
rsaEncrypt.loadPrivateKey(privateKeyWubo);
System.out.println("加載私鑰成功");
} catch (Exception e) {
System.err.println(e.getMessage());
System.err.println("加載私鑰失敗");
}
//測試字元串
String encryptStr= "test";
System.out.println("加密前:");
System.out.println(encryptStr);
try {
//加密
byte[] enResult = rsaEncrypt.siyaoEncrypt(rsaEncrypt.getPrivateKey(), encryptStr.getBytes());
//解密
String result = rsaEncrypt.gongyaoDecrypt(rsaEncrypt.getPublicKey(), enResult);
System.out.println("加密後:"+com.yctc.test.Base64.encode(enResult));
System.out.println("解密後:"+result);
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
無論是公鑰加密私鑰解密，還是公鑰解密私鑰加密，都是一樣的，關鍵在于私鑰加密就必須要公鑰解密，公鑰加密就必須要私鑰解密。
![一張圖了解RSA加解密與加驗簽[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)