Java中利用RSA演算法進行加密解密
阿新 • • 發佈：2019-02-17
首先需要兩個工具類
package cnsts.common.utils; import java.io.BufferedReader; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.math.BigInteger; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.PrivateKey; import java.security.PublicKey; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.RSAPublicKeySpec; import java.security.spec.X509EncodedKeySpec; import javax.crypto.Cipher; /** * Created by wk on 2017/2/14. */ public class RSAUtils { private static String RSA = "RSA"; /** *//** * RSA最大加密明文大小 */ private static final int MAX_ENCRYPT_BLOCK = 117; /** * 隨機生成RSA金鑰對(預設金鑰長度為1024) * * @return */ public static KeyPair generateRSAKeyPair() { return generateRSAKeyPair(1024); } /** * 隨機生成RSA金鑰對 * * @param keyLength * 金鑰長度，範圍：512～2048<br> * 一般1024 * @return */ public static KeyPair generateRSAKeyPair(int keyLength) { try { KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA); kpg.initialize(keyLength); return kpg.genKeyPair(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); return null; } } /** * 用公鑰加密 <br> * 每次加密的位元組數，不能超過金鑰的長度值減去11 * * @param data * 需加密資料的byte資料 * @param publicKey 公鑰 * @return 加密後的byte型資料 */ public static byte[] encryptData(byte[] data, PublicKey publicKey) { try { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding"); // 編碼前設定編碼方式及金鑰 cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 傳入編碼資料並返回編碼結果 int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對資料分段加密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_ENCRYPT_BLOCK) { cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_ENCRYPT_BLOCK; } byte[] encryptedData = out.toByteArray(); out.close(); return encryptedData; } catch (Exception e) { e.printStackTrace(); return null; } } /** * 用私鑰解密 * * @param encryptedData * 經過encryptedData()加密返回的byte資料 * @param privateKey * 私鑰 * @return */ public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey) { try { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding"); cipher.init(Cipher.DECRYPT_MODE, privateKey); return cipher.doFinal(encryptedData); } catch (Exception e) { e.printStackTrace(); return null; } } /** * 通過公鑰byte[](publicKey.getEncoded())將公鑰還原，適用於RSA演算法 * * @param keyBytes * @return * @throws NoSuchAlgorithmException * @throws InvalidKeySpecException */ public static PublicKey getPublicKey(byte[] keyBytes) throws NoSuchAlgorithmException, InvalidKeySpecException { X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(RSA); PublicKey publicKey = keyFactory.generatePublic(keySpec); return publicKey; } /** * 通過私鑰byte[]將公鑰還原，適用於RSA演算法 * * @param keyBytes * @return * @throws NoSuchAlgorithmException * @throws InvalidKeySpecException */ public static PrivateKey getPrivateKey(byte[] keyBytes) throws NoSuchAlgorithmException, InvalidKeySpecException { PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(RSA); PrivateKey privateKey = keyFactory.generatePrivate(keySpec); return privateKey; } /** * 使用N、e值還原公鑰 * * @param modulus * @param publicExponent * @return * @throws NoSuchAlgorithmException * @throws InvalidKeySpecException */ public static PublicKey getPublicKey(String modulus, String publicExponent) throws NoSuchAlgorithmException, InvalidKeySpecException { BigInteger bigIntModulus = new BigInteger(modulus); BigInteger bigIntPrivateExponent = new BigInteger(publicExponent); RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent); KeyFactory keyFactory = KeyFactory.getInstance(RSA); PublicKey publicKey = keyFactory.generatePublic(keySpec); return publicKey; } /** * 使用N、d值還原私鑰 * * @param modulus * @param privateExponent * @return * @throws NoSuchAlgorithmException * @throws InvalidKeySpecException */ public static PrivateKey getPrivateKey(String modulus, String privateExponent) throws NoSuchAlgorithmException, InvalidKeySpecException { BigInteger bigIntModulus = new BigInteger(modulus); BigInteger bigIntPrivateExponent = new BigInteger(privateExponent); RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent); KeyFactory keyFactory = KeyFactory.getInstance(RSA); PrivateKey privateKey = keyFactory.generatePrivate(keySpec); return privateKey; } /** * 從字串中載入公鑰 * * @param publicKeyStr * 公鑰資料字串 * @throws Exception * 載入公鑰時產生的異常 */ public static PublicKey loadPublicKey(String publicKeyStr) throws Exception { try { byte[] buffer = Base64Utils.decode(publicKeyStr); KeyFactory keyFactory = KeyFactory.getInstance(RSA); X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer); return (RSAPublicKey) keyFactory.generatePublic(keySpec); } catch (NoSuchAlgorithmException e) { throw new Exception("無此演算法"); } catch (InvalidKeySpecException e) { throw new Exception("公鑰非法"); } catch (NullPointerException e) { throw new Exception("公鑰資料為空"); } } /** * 從字串中載入私鑰<br> * 載入時使用的是PKCS8EncodedKeySpec（PKCS#8編碼的Key指令）。 * * @param privateKeyStr * @return * @throws Exception */ public static PrivateKey loadPrivateKey(String privateKeyStr) throws Exception { try { byte[] buffer = Base64Utils.decode(privateKeyStr); // X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer); PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer); KeyFactory keyFactory = KeyFactory.getInstance(RSA); return (RSAPrivateKey) keyFactory.generatePrivate(keySpec); } catch (NoSuchAlgorithmException e) { throw new Exception("無此演算法"); } catch (InvalidKeySpecException e) { throw new Exception("私鑰非法"); } catch (NullPointerException e) { throw new Exception("私鑰資料為空"); } } /** * 從檔案中輸入流中載入公鑰 * * @param in * 公鑰輸入流 * @throws Exception * 載入公鑰時產生的異常 */ public static PublicKey loadPublicKey(InputStream in) throws Exception { try { return loadPublicKey(readKey(in)); } 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"); } } /** * 從檔案中載入私鑰 * * @param in * 私鑰檔名 * @return 是否成功 * @throws Exception */ public static PrivateKey loadPrivateKey(InputStream in) throws Exception { try { return loadPrivateKey(readKey(in)); } 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"); } } /** * 讀取金鑰資訊 * * @param in * @return * @throws IOException */ private static String readKey(InputStream in) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(in)); String readLine = null; StringBuilder sb = new StringBuilder(); while ((readLine = br.readLine()) != null) { if (readLine.charAt(0) == '-') { continue; } else { sb.append(readLine); sb.append('\r'); } } return sb.toString(); } /** * 列印公鑰資訊 * * @param publicKey */ public static void printPublicKeyInfo(PublicKey publicKey) { RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey; System.out.println("----------RSAPublicKey----------"); System.out.println("Modulus.length=" + rsaPublicKey.getModulus().bitLength()); System.out.println("Modulus=" + rsaPublicKey.getModulus().toString()); System.out.println("PublicExponent.length=" + rsaPublicKey.getPublicExponent().bitLength()); System.out.println("PublicExponent=" + rsaPublicKey.getPublicExponent().toString()); } public static void printPrivateKeyInfo(PrivateKey privateKey) { RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey; System.out.println("----------RSAPrivateKey ----------"); System.out.println("Modulus.length=" + rsaPrivateKey.getModulus().bitLength()); System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString()); System.out.println("PrivateExponent.length=" + rsaPrivateKey.getPrivateExponent().bitLength()); System.out.println("PrivatecExponent=" + rsaPrivateKey.getPrivateExponent().toString()); } }
package cnsts.common.utils; import java.io.UnsupportedEncodingException; /** * Created by wk on 2017/2/14. */ public class Base64Utils { private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 }; /** * 加密 * * @param data * @return */ public static String encode(byte[] data) { StringBuffer sb = new StringBuffer(); int len = data.length; int i = 0; int b1, b2, b3; while (i < len) { b1 = data[i++] & 0xff; if (i == len) { sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[(b1 & 0x3) << 4]); sb.append("=="); break; } b2 = data[i++] & 0xff; if (i == len) { sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); sb.append(base64EncodeChars[(b2 & 0x0f) << 2]); sb.append("="); break; } b3 = data[i++] & 0xff; sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]); sb.append(base64EncodeChars[b3 & 0x3f]); } return sb.toString(); } /** * 解密 * * @param str * @return */ public static byte[] decode(String str) { try { return decodePrivate(str); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return new byte[] {}; } private static byte[] decodePrivate(String str) throws UnsupportedEncodingException { StringBuffer sb = new StringBuffer(); byte[] data = null; data = str.getBytes("US-ASCII"); int len = data.length; int i = 0; int b1, b2, b3, b4; while (i < len) { do { b1 = base64DecodeChars[data[i++]]; } while (i < len && b1 == -1); if (b1 == -1) break; do { b2 = base64DecodeChars[data[i++]]; } while (i < len && b2 == -1); if (b2 == -1) break; sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4))); do { b3 = data[i++]; if (b3 == 61) return sb.toString().getBytes("iso8859-1"); b3 = base64DecodeChars[b3]; } while (i < len && b3 == -1); if (b3 == -1) break; sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2))); do { b4 = data[i++]; if (b4 == 61) return sb.toString().getBytes("iso8859-1"); b4 = base64DecodeChars[b4]; } while (i < len && b4 == -1); if (b4 == -1) break; sb.append((char) (((b3 & 0x03) << 6) | b4)); } return sb.toString().getBytes("iso8859-1"); } }
然後新建一個用來加密解密的工具類
package cnsts.common.utils; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.InputStream; import java.security.PrivateKey; import java.security.PublicKey; public class SecurityUtils { /** * 解密 * @param cipherText 密文 * @return 返回解密後的字串 * @throws Exception */ public static String decrypt(String cipherText) throws Exception{ // 從檔案中得到私鑰 FileInputStream inPrivate = new FileInputStream( SecurityUtils.class.getClassLoader().getResource("").getPath() + "/pkcs8_private_key.pem"); PrivateKey privateKey = RSAUtils.loadPrivateKey(inPrivate); byte[] decryptByte = RSAUtils.decryptData(Base64Utils.decode(cipherText), privateKey); String decryptStr = new String(decryptByte,"utf-8"); return decryptStr; } /** * 加密 * @param plainTest 明文 * @return 返回加密後的密文 * @throws Exception */ public static String encrypt(String plainTest) throws Exception{ FileInputStream inPublic = new FileInputStream( SecurityUtils.class.getClassLoader().getResource("").getPath() + "/rsa_public_key.pem"); PublicKey publicKey = RSAUtils.loadPublicKey(inPublic); // 加密 byte[] encryptByte = RSAUtils.encryptData(plainTest.getBytes(), publicKey); String afterencrypt = Base64Utils.encode(encryptByte); return afterencrypt; } }