本文實例講述了Java RSA加密解密實現方法。分享給大家供大家參考，具體如下：
該工具類中用到了BASE64，需要借助第三方類庫：javabase64-1.3.1.jar
javabase64-1.3.1.jar 本站下載地址。
注意：
RSA加密明文最大長度117字節，解密要求密文最大長度為128字節，所以在加密和解密的過程中需要分塊進行。
RSA加密對明文的長度是有限制的，如果加密數據過大會拋出如下異常：
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Exception in thread "main" javax.crypto.IllegalBlockSizeException: Data must not be longer than 117 bytes at com.sun.crypto.provider.RSACipher.a(DashoA13*..) at com.sun.crypto.provider.RSACipher.engineDoFinal(DashoA13*..) at javax.crypto.Cipher.doFinal(DashoA13*..) |
RSAUtils.java
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package security;import java.io.ByteArrayOutputStream;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.Signature;import java.security.interfaces.RSAPrivateKey;import java.security.interfaces.RSAPublicKey;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import java.util.HashMap;import java.util.Map;import javax.crypto.Cipher;/** *//** * <p> * RSA公鑰/私鑰/簽名工具包 * </p> * <p> * 羅納德·李維斯特（Ron [R]ivest）、阿迪·薩莫爾（Adi [S]hamir）和倫納德·阿德曼（Leonard [A]dleman） * </p> * <p> * 字符串格式的密鑰在未在特殊說明情況下都為BASE64編碼格式<br/> * 由于非對稱加密速度極其緩慢，一般文件不使用它來加密而是使用對稱加密，<br/> * 非對稱加密算法可以用來對對稱加密的密鑰加密，這樣保證密鑰的安全也就保證了數據的安全 * </p> * * @author IceWee * @date 2012-4-26 * @version 1.0 */public class RSAUtils { /** *//** * 加密算法RSA */ public static final String KEY_ALGORITHM = "RSA"; /** *//** * 簽名算法 */ public static final String SIGNATURE_ALGORITHM = "MD5withRSA"; /** *//** * 獲取公鑰的key */ private static final String PUBLIC_KEY = "RSAPublicKey"; /** *//** * 獲取私鑰的key */ private static final String PRIVATE_KEY = "RSAPrivateKey"; /** *//** * 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; /** *//** * <p> * 生成密鑰對(公鑰和私鑰) * </p> * * @return * @throws Exception */ public static Map<String, Object> genKeyPair() throws Exception { KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM); keyPairGen.initialize(1024); KeyPair keyPair = keyPairGen.generateKeyPair(); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); Map<String, Object> keyMap = new HashMap<String, Object>(2); keyMap.put(PUBLIC_KEY, publicKey); keyMap.put(PRIVATE_KEY, privateKey); return keyMap; } /** *//** * <p> * 用私鑰對信息生成數字簽名 * </p> * * @param data 已加密數據 * @param privateKey 私鑰(BASE64編碼) * * @return * @throws Exception */ public static String sign(byte[] data, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec); Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM); signature.initSign(privateK); signature.update(data); return Base64Utils.encode(signature.sign()); } /** *//** * <p> * 校驗數字簽名 * </p> * * @param data 已加密數據 * @param publicKey 公鑰(BASE64編碼) * @param sign 數字簽名 * * @return * @throws Exception * */ public static boolean verify(byte[] data, String publicKey, String sign) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PublicKey publicK = keyFactory.generatePublic(keySpec); Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM); signature.initVerify(publicK); signature.update(data); return signature.verify(Base64Utils.decode(sign)); } /** *//** * <P> * 私鑰解密 * </p> * * @param encryptedData 已加密數據 * @param privateKey 私鑰(BASE64編碼) * @return * @throws Exception */ public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key privateK = keyFactory.generatePrivate(pkcs8KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, privateK); int inputLen = encryptedData.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] decryptedData = out.toByteArray(); out.close(); return decryptedData; } /** *//** * <p> * 公鑰解密 * </p> * * @param encryptedData 已加密數據 * @param publicKey 公鑰(BASE64編碼) * @return * @throws Exception */ public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key publicK = keyFactory.generatePublic(x509KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, publicK); int inputLen = encryptedData.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] decryptedData = out.toByteArray(); out.close(); return decryptedData; } /** *//** * <p> * 公鑰加密 * </p> * * @param data 源數據 * @param publicKey 公鑰(BASE64編碼) * @return * @throws Exception */ public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key publicK = keyFactory.generatePublic(x509KeySpec); // 對數據加密 Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, publicK); int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段加密 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; } /** *//** * <p> * 私鑰加密 * </p> * * @param data 源數據 * @param privateKey 私鑰(BASE64編碼) * @return * @throws Exception */ public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key privateK = keyFactory.generatePrivate(pkcs8KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, privateK); int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段加密 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; } /** *//** * <p> * 獲取私鑰 * </p> * * @param keyMap 密鑰對 * @return * @throws Exception */ public static String getPrivateKey(Map<String, Object> keyMap) throws Exception { Key key = (Key) keyMap.get(PRIVATE_KEY); return Base64Utils.encode(key.getEncoded()); } /** *//** * <p> * 獲取公鑰 * </p> * * @param keyMap 密鑰對 * @return * @throws Exception */ public static String getPublicKey(Map<String, Object> keyMap) throws Exception { Key key = (Key) keyMap.get(PUBLIC_KEY); return Base64Utils.encode(key.getEncoded()); }} |
Base64Utils.java
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package security;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import it.sauronsoftware.base64.Base64;/** *//** * <p> * BASE64編碼解碼工具包 * </p> * <p> * 依賴javabase64-1.3.1.jar * </p> * * @author IceWee * @date 2012-5-19 * @version 1.0 */public class Base64Utils { /** *//** * 文件讀取緩沖區大小 */ private static final int CACHE_SIZE = 1024; /** *//** * <p> * BASE64字符串解碼為二進制數據 * </p> * * @param base64 * @return * @throws Exception */ public static byte[] decode(String base64) throws Exception { return Base64.decode(base64.getBytes()); } /** *//** * <p> * 二進制數據編碼為BASE64字符串 * </p> * * @param bytes * @return * @throws Exception */ public static String encode(byte[] bytes) throws Exception { return new String(Base64.encode(bytes)); } /** *//** * <p> * 將文件編碼為BASE64字符串 * </p> * <p> * 大文件慎用，可能會導致內存溢出 * </p> * * @param filePath 文件絕對路徑 * @return * @throws Exception */ public static String encodeFile(String filePath) throws Exception { byte[] bytes = fileToByte(filePath); return encode(bytes); } /** *//** * <p> * BASE64字符串轉回文件 * </p> * * @param filePath 文件絕對路徑 * @param base64 編碼字符串 * @throws Exception */ public static void decodeToFile(String filePath, String base64) throws Exception { byte[] bytes = decode(base64); byteArrayToFile(bytes, filePath); } /** *//** * <p> * 文件轉換為二進制數組 * </p> * * @param filePath 文件路徑 * @return * @throws Exception */ public static byte[] fileToByte(String filePath) throws Exception { byte[] data = new byte[0]; File file = new File(filePath); if (file.exists()) { FileInputStream in = new FileInputStream(file); ByteArrayOutputStream out = new ByteArrayOutputStream(2048); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); data = out.toByteArray(); } return data; } /** *//** * <p> * 二進制數據寫文件 * </p> * * @param bytes 二進制數據 * @param filePath 文件生成目錄 */ public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception { InputStream in = new ByteArrayInputStream(bytes); File destFile = new File(filePath); if (!destFile.getParentFile().exists()) { destFile.getParentFile().mkdirs(); } destFile.createNewFile(); OutputStream out = new FileOutputStream(destFile); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); }} |
RSATester.java
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package security;import java.util.Map;public class RSATester { static String publicKey; static String privateKey; static { try { Map<String, Object> keyMap = RSAUtils.genKeyPair(); publicKey = RSAUtils.getPublicKey(keyMap); privateKey = RSAUtils.getPrivateKey(keyMap); System.err.println("公鑰: \n\r" + publicKey); System.err.println("私鑰： \n\r" + privateKey); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) throws Exception { test(); testSign(); } static void test() throws Exception { System.err.println("公鑰加密——私鑰解密"); String source = "這是一行沒有任何意義的文字，你看完了等于沒看，不是嗎？"; System.out.println("\r加密前文字：\r\n" + source); byte[] data = source.getBytes(); byte[] encodedData = RSAUtils.encryptByPublicKey(data, publicKey); System.out.println("加密后文字：\r\n" + new String(encodedData)); byte[] decodedData = RSAUtils.decryptByPrivateKey(encodedData, privateKey); String target = new String(decodedData); System.out.println("解密后文字: \r\n" + target); } static void testSign() throws Exception { System.err.println("私鑰加密——公鑰解密"); String source = "這是一行測試RSA數字簽名的無意義文字"; System.out.println("原文字：\r\n" + source); byte[] data = source.getBytes(); byte[] encodedData = RSAUtils.encryptByPrivateKey(data, privateKey); System.out.println("加密后：\r\n" + new String(encodedData)); byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, publicKey); String target = new String(decodedData); System.out.println("解密后: \r\n" + target); System.err.println("私鑰簽名——公鑰驗證簽名"); String sign = RSAUtils.sign(encodedData, privateKey); System.err.println("簽名:\r" + sign); boolean status = RSAUtils.verify(encodedData, publicKey, sign); System.err.println("驗證結果:\r" + status); }} |
希望本文所述對大家java程序設計有所幫助。
原文鏈接：http://blog.csdn.net/centralperk/article/details/8538697
