Java-文件加密傳輸（摘要+簽名）
文件加密傳輸其實就是將文件以二進制格式進行傳輸。
其中加密文件主要由：源文件二進制文件、源文件數字摘要、數字簽名、特征碼等等組成。
摘要可確認文件的唯一性，數字簽名則是對摘要進行了加密。
本文主要記錄使用RSA加密方式
其中生成RSA密鑰主要介紹二種方式：
1、安裝openssl情況下使用Linux命令生成
2、Java代碼實現
一、公私鑰生成
1、linux
1、查看openssl版本
openssl version -a
2、生成私鑰
openssl genrsa -out rsa_private_key.pem 2048
會生成rsa_private_key.pem私鑰文件，私鑰文件不能使用
3、生成公鑰
openssl rsa -in rsa_private_key.pem -out rsa_public_key.pem -puboutopenssl pkcs8 -topk8 -inform PEM -outform DER -in private_key.pem -out private_key.der -nocrypt
私鑰文件不能使用
4、私鑰文件PKCS#8編碼
openssl pkcs8 -topk8 -in rsa_private_key.pem -out pkcs8_rsa_private_key.pem
此處生成的私鑰文件方可用於Java
2、Java
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import org.apache.commons.codec.binary.Base64;
public class RSAEncrypt {
/**
* 字節數據轉字符串專用集合
*/
private static final char[] HEX_CHAR = {'0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
private static final String PRIVATE_BEGIN = "-----BEGIN PRIVATE KEY-----";
private static final String PRIVATE_END = "-----END PRIVATE KEY-----";
private static final String PUBLIC_BEGIN = "-----BEGIN PUBLIC KEY-----";
private static final String PUBLIC_END = "-----END PUBLIC KEY-----";
/**
* 1、隨機生成密鑰對
*
* @param filePath 密鑰存放目錄
*/
public void genKeyPair(String filePath) {
// KeyPairGenerator類用於生成公鑰和私鑰對，基於RSA算法生成對象
KeyPairGenerator keyPairGen = null;
try {
keyPairGen = KeyPairGenerator.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
// 初始化密鑰對生成器，密鑰大小為96-1024位
keyPairGen.initialize(1024, new SecureRandom());
// 生成一個密鑰對，保存在keyPair中
KeyPair keyPair = keyPairGen.generateKeyPair();
// 得到私鑰
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
// 得到公鑰
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
try {
// 得到公鑰字符串
Base64 base64 = new Base64();
String publicKeyString = new String(base64.encode(publicKey.getEncoded()));
// 得到私鑰字符串
String privateKeyString = new String(base64.encode(privateKey.getEncoded()));
// 將密鑰對寫入到文件
FileWriter pubfw = new FileWriter(filePath + "\\publicKey.pem");
FileWriter prifw = new FileWriter(filePath + "\\privateKey.pem");
BufferedWriter pubbw = new BufferedWriter(pubfw);
BufferedWriter pribw = new BufferedWriter(prifw);
pubbw.write(publicKeyString);
pribw.write(privateKeyString);
pubbw.flush();
pubbw.close();
pubfw.close();
pribw.flush();
pribw.close();
prifw.close();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 2、從本地文件中讀取公鑰
*
* @param path 公鑰路徑
* @return 公鑰字符串
* @throws Exception 異常信息
*/
public String loadPublicKeyByFile(String path) throws Exception {
try {
BufferedReader br = new BufferedReader(new FileReader(path));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
// 去除公鑰頭部底部
if (!readLine.equals(PUBLIC_BEGIN) && !readLine.equals(PUBLIC_END)) {
sb.append(readLine);
}
}
br.close();
return sb.toString();
} catch (IOException e) {
throw new Exception("公鑰數據流讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("公鑰輸入流為空");
}
}
/**
* 3、字符串公鑰轉公鑰對象
*
* @param publicKeyStr 公鑰字符串類型
* @return 公鑰對象
* @throws Exception 異常信息
*/
public RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
throws Exception {
try {
Base64 base64 = new Base64();
byte[] buffer = base64.decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("無此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公鑰非法");
} catch (NullPointerException e) {
throw new Exception("公鑰數據為空");
}
}
/**
* 4、從本地文件中讀取私鑰
*
* @param path 私鑰文件路徑
* @return 私鑰字符串
* @throws Exception 異常信息
*/
public String loadPrivateKeyByFile(String path) throws Exception {
try {
BufferedReader br = new BufferedReader(new FileReader(path));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
//去除私鑰頭部底部
if (!readLine.equals(PRIVATE_BEGIN) && !readLine.equals(PRIVATE_END)) {
sb.append(readLine);
} else {
}
}
br.close();
return sb.toString();
} catch (IOException e) {
throw new Exception("私鑰數據讀取錯誤");
} catch (NullPointerException e) {
throw new Exception("私鑰輸入流為空");
}
}
/**
* 5、字符串公鑰轉公鑰對象
*
* @param privateKeyStr 私鑰字符串類型
* @return 私鑰對象
* @throws Exception 異常信息
*/
public RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
throws Exception {
try {
Base64 base64 = new Base64();
byte[] buffer = base64.decode(privateKeyStr);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return (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 (NullPointerException e) {
throw new Exception("私鑰數據為空");
}
}
/**
* 6、公鑰加密過程
*
* @param publicKey 公鑰
* @param plainTextData 明文數據
* @return
* @throws Exception 加密過程中的異常信息
*/
public byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData)
throws Exception {
if (publicKey == null) {
throw new Exception("加密公鑰為空, 請設置");
}
Cipher cipher = null;
try {
// 使用默認RSA
cipher = Cipher.getInstance("RSA");
// cipher= Cipher.getInstance("RSA", 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("明文數據已損壞");
}
}
/**
* 7、私鑰加密過程
*
* @param privateKey 私鑰
* @param plainTextData 明文數據
* @return
* @throws Exception 加密過程中的異常信息
*/
public byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData)
throws Exception {
if (privateKey == null) {
throw new Exception("加密私鑰為空, 請設置");
}
Cipher cipher = null;
try {
// 使用默認RSA
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
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("加密私鑰非法,請檢查");
} catch (IllegalBlockSizeException e) {
throw new Exception("明文長度非法");
} catch (BadPaddingException e) {
throw new Exception("明文數據已損壞");
}
}
/**
* 8、私鑰解密過程
*
* @param privateKey 私鑰
* @param cipherData 密文數據
* @return 明文
* @throws Exception 解密過程中的異常信息
*/
public byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData)
throws Exception {
if (privateKey == null) {
throw new Exception("解密私鑰為空, 請設置");
}
Cipher cipher = null;
try {
// 使用默認RSA
cipher = Cipher.getInstance("RSA");
// cipher= Cipher.getInstance("RSA", 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("密文數據已損壞");
}
}
/**
* 9、公鑰解密過程
*
* @param publicKey 公鑰
* @param cipherData 密文數據
* @return 明文
* @throws Exception 解密過程中的異常信息
*/
public byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData)
throws Exception {
if (publicKey == null) {
throw new Exception("解密公鑰為空, 請設置");
}
Cipher cipher = null;
try {
// 使用默認RSA
cipher = Cipher.getInstance("RSA");
// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
cipher.init(Cipher.DECRYPT_MODE, publicKey);
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("解密公鑰非法,請檢查");
} catch (IllegalBlockSizeException e) {
throw new Exception("密文長度非法");
} catch (BadPaddingException e) {
throw new Exception("密文數據已損壞");
}
}
/**
* 10、字節數據轉十六進制字符串
*
* @param data 輸入數據
* @return 十六進制內容
*/
public String byteArrayToString(byte[] data) {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < data.length; i++) {
// 取出字節的高四位 作為索引得到相應的十六進制標識符 注意無符號右移
stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
// 取出字節的低四位 作為索引得到相應的十六進制標識符
stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
if (i < data.length - 1) {
stringBuilder.append(' ');
}
}
return stringBuilder.toString();
}
}
二、調用
/**
* 生成加密后文件
*
* @param oldFilePath 需要加密文件路徑+名稱
* @param newFilePath 加密后文件路徑+名稱
* @param privatePath 私鑰文件路徑+名稱
*/
public void fileEncrypt(String oldFilePath, String newFilePath, String privatePath) {
ByteUtil byteUtil = new ByteUtil();
//文件格式：特征碼+原始升級包長度+數字簽名長度+原始包內容+數字簽名
byte[] code = byteUtil.intToByteArray(0x9F2308DC);
RSAEncrypt rsaEncrypt = new RSAEncrypt();
try {
//1、特征碼寫入
OutputStream out = new FileOutputStream(new File(newFilePath));
out.write(code, 0, 4);
//2、原始升級包長度寫入
byte[] fileByte = byteUtil.File2byte(oldFilePath);
int L1 = fileByte.length;
byte[] a = byteUtil.intToByteArray(L1);
out.write(a, 0, 4);
//文件摘要生成
MsgDigestDemo msgDigestDemo = new MsgDigestDemo();
MessageDigest md5Digest = MessageDigest.getInstance("MD5");
md5Digest.update(msgDigestDemo.fileBytes(oldFilePath));
byte[] md5Encoded = md5Digest.digest();
log.info("==========MD5摘要:{}==========", Base64.encodeBase64URLSafeString(md5Encoded));
String privateKey = rsaEncrypt.loadPrivateKeyByFile(privatePath);
RSAPrivateKey privateKeyfile = rsaEncrypt.loadPrivateKeyByStr(privateKey);
//生成簽名(摘要加密過程)
byte[] signature = rsaEncrypt.encrypt(privateKeyfile, md5Encoded);
//3、簽名長度
int L2 = signature.length;
byte[] c = byteUtil.intToByteArray(L2);
out.write(c, 0, 4);
//4、原始升級包內容寫入
out.write(fileByte, 0, L1);
//5、數字簽名寫入
out.write(signature, 0, L2);
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
MD5摘要計算
public class MsgDigestDemo {
public byte[] fileBytes(String filePath) {
try {
File file = new File(filePath);
ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
FileInputStream in = new FileInputStream(file);
byte[] fileByte = new byte[1024];
int n;
while ((n = in.read(fileByte)) != -1) {
out.write(fileByte, 0, n);
}
in.close();
byte[] data = out.toByteArray();
out.close();
return data;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
參考：https://www.cnblogs.com/PollyLuo/p/9046610.html
