如何用java RSA生成生成公鑰私鑰(非對稱加密)
阿新 • • 發佈:2019-01-25
言簡意賅,直接見程式碼:
package com; import java.security.Key; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.SecureRandom; import java.security.Signature; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Date; import java.util.HashMap; import java.util.Map; import javax.crypto.Cipher; import sun.misc.BASE64Decoder; import sun.misc.BASE64Encoder; public class CreateSecretKey { public static final String KEY_ALGORITHM = "RSA"; private static final String PUBLIC_KEY = "RSAPublicKey"; private static final String PRIVATE_KEY = "RSAPrivateKey"; public static final String SIGNATURE_ALGORITHM="MD5withRSA"; /** * RSA最大加密明文大小 */ private static final int MAX_ENCRYPT_BLOCK = 117; /** * RSA最大解密密文大小 */ private static final int MAX_DECRYPT_BLOCK = 128; //獲得公鑰字串 public static String getPublicKeyStr(Map<String, Object> keyMap) throws Exception { //獲得map中的公鑰物件 轉為key物件 Key key = (Key) keyMap.get(PUBLIC_KEY); //編碼返回字串 return encryptBASE64(key.getEncoded()); } //獲得私鑰字串 public static String getPrivateKeyStr(Map<String, Object> keyMap) throws Exception { //獲得map中的私鑰物件 轉為key物件 Key key = (Key) keyMap.get(PRIVATE_KEY); //編碼返回字串 return encryptBASE64(key.getEncoded()); } //獲取公鑰 public static PublicKey getPublicKey(String key) throws Exception { byte[] keyBytes; keyBytes = (new BASE64Decoder()).decodeBuffer(key); X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PublicKey publicKey = keyFactory.generatePublic(keySpec); return publicKey; } //獲取私鑰 public static PrivateKey getPrivateKey(String key) throws Exception { byte[] keyBytes; keyBytes = (new BASE64Decoder()).decodeBuffer(key); PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PrivateKey privateKey = keyFactory.generatePrivate(keySpec); return privateKey; } //解碼返回byte public static byte[] decryptBASE64(String key) throws Exception { return (new BASE64Decoder()).decodeBuffer(key); } //編碼返回字串 public static String encryptBASE64(byte[] key) throws Exception { return (new BASE64Encoder()).encodeBuffer(key); } //***************************簽名和驗證******************************* public static byte[] sign(byte[] data,String privateKeyStr) throws Exception{ PrivateKey priK = getPrivateKey(privateKeyStr); Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM); sig.initSign(priK); sig.update(data); return sig.sign(); } public static boolean verify(byte[] data,byte[] sign,String publicKeyStr) throws Exception{ PublicKey pubK = getPublicKey(publicKeyStr); Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM); sig.initVerify(pubK); sig.update(data); return sig.verify(sign); } //************************加密解密************************** public static byte[] encrypt(byte[] plainText,String publicKeyStr)throws Exception{ PublicKey publicKey = getPublicKey(publicKeyStr); Cipher cipher = Cipher.getInstance(KEY_ALGORITHM); cipher.init(Cipher.ENCRYPT_MODE, publicKey); int inputLen = plainText.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; int i = 0; byte[] cache; while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_ENCRYPT_BLOCK) { cache = cipher.doFinal(plainText, offSet, MAX_ENCRYPT_BLOCK); } else { cache = cipher.doFinal(plainText, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_ENCRYPT_BLOCK; } byte[] encryptText = out.toByteArray(); out.close(); return encryptText; } public static byte[] decrypt(byte[] encryptText,String privateKeyStr)throws Exception{ PrivateKey privateKey = getPrivateKey(privateKeyStr); Cipher cipher = Cipher.getInstance(KEY_ALGORITHM); cipher.init(Cipher.DECRYPT_MODE, privateKey); int inputLen = encryptText.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對資料分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptText, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptText, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] plainText = out.toByteArray(); out.close(); return plainText; } public static void main(String[] args) { Map<String, Object> keyMap; byte[] cipherText; String input = "Hello World!"; try { keyMap = initKey(); String publicKey = getPublicKeyStr(keyMap); System.out.println("公鑰------------------"); System.out.println(publicKey); String privateKey = getPrivateKeyStr(keyMap); System.out.println("私鑰------------------"); System.out.println(privateKey); System.out.println("測試可行性-------------------"); System.out.println("明文======="+input); cipherText = encrypt(input.getBytes(),publicKey); //加密後的東西 System.out.println("密文======="+new String(cipherText)); //開始解密 byte[] plainText = decrypt(cipherText,privateKey); System.out.println("解密後明文===== " + new String(plainText)); System.out.println("驗證簽名-----------"); String str="被簽名的內容"; System.out.println("\n原文:"+str); byte[] signature=sign(str.getBytes(),privateKey); boolean status=verify(str.getBytes(), signature,publicKey); System.out.println("驗證情況:"+status); } catch (Exception e) { e.printStackTrace(); } } }