RSA公钥私钥在在实际应用的具体运用
在《在Linux下如何使用openssl生成RSA公钥和私钥对》一文中，讲述了在Linux环境下如何生成RSA公钥和私钥，但在Java中，我们又是如何去很好的用它们呢？下面我来看下两个案例，特别是RSA私钥的生成是有输入密码的（在生产环境上一般都应该是这样用的），即在产生**对时有输入密码，如输出了12345678。
一.加签验签
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.Security;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.util.Arrays;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMReader;
import org.bouncycastle.openssl.PasswordFinder;
import org.bouncycastle.util.encoders.Hex;
public class SignatureExample {
public static void main(String [] args) throws Exception {
Security.addProvider(new BouncyCastleProvider());
String message = "hello world";
File privateKey = new File("C:/test/key");
KeyPair keyPair = readKeyPair(privateKey, "12345678".toCharArray());
Signature signature = Signature.getInstance("SHA256WithRSAEncryption");
signature.initSign(keyPair.getPrivate());
signature.update(message.getBytes());
byte [] signatureBytes = signature.sign();
System.out.println(new String(Hex.encode(signatureBytes)));
Signature verifier = Signature.getInstance("SHA256WithRSAEncryption");
verifier.initVerify(keyPair.getPublic());
verifier.update(message.getBytes());
if (verifier.verify(signatureBytes)) {
System.out.println("Signature is valid");
} else {
System.out.println("Signature is invalid");
}
}
private static KeyPair readKeyPair(File privateKey, char [] keyPassword) throws IOException {
FileReader fileReader = new FileReader(privateKey);
PEMReader r = new PEMReader(fileReader, new DefaultPasswordFinder(keyPassword));
try {
return (KeyPair) r.readObject();
} catch (IOException ex) {
throw new IOException("The private key could not be decrypted", ex);
} finally {
r.close();
fileReader.close();
}
}
private static class DefaultPasswordFinder implements PasswordFinder {
private final char [] password;
private DefaultPasswordFinder(char [] password) {
this.password = password;
}
@Override
public char[] getPassword() {
return Arrays.copyOf(password, password.length);
}
}
}
二.通过JSch上传文件到SFTP，并从SFTP服务器上下载
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
import java.util.Date;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.io.Closeables;
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.SftpATTRS;
import com.jcraft.jsch.SftpException;
public class SftpUtil {
private final static Logger logger = LoggerFactory.getLogger(SftpUtil.class);
private final static String STYLE_yyyyMMdd = "yyyyMMdd";
public static String getCurrentDir() {
return new SimpleDateFormat(STYLE_yyyyMMdd).format(new Date());
}
private static boolean isDirExist(ChannelSftp sftp, String directory) {
boolean isDirExistFlag = false;
try {
SftpATTRS sftpATTRS = sftp.lstat(directory);
isDirExistFlag = sftpATTRS.isDir();
}catch(Exception e) {
isDirExistFlag = false;
}
return isDirExistFlag;
}
private static boolean createDir(ChannelSftp sftp, String dirPath) {
boolean res = false;
try {
sftp.cd("/");
if(isDirExist(sftp, dirPath)) {
return true;
}
String pathArray[] = dirPath.split("/");
for(String path : pathArray) {
if(path.equals("")) {
continue;
}
if(isDirExist(sftp, path)) {
sftp.cd(path);
}else {
sftp.mkdir(path);
sftp.cd(path);
}
}
res = true;
}catch(Exception e) {
res = false;
logger.warn("创建目录异常!", e);
}finally {
try {
sftp.cd("/");
} catch (SftpException e) {
logger.warn("切换到根目录异常!", e);
}
}
return res;
}
/**
* 上传文件
*/
public static void upload(String user, String ip, int port, String password, String privateKeyPath, String passPhrase, String remoteFileName,
String remoteFilePath, String localFileName) throws Exception {
ChannelSftp sftp = null;
FileInputStream input = null;
Session sshSession = null;
try {
JSch jsch = new JSch();
sshSession = jsch.getSession(user, ip, port);
// 判断鉴权方式
if(StringUtils.isNotEmpty(password)) {
sshSession.setPassword(password);
}else if(StringUtils.isNotEmpty(passPhrase)){
jsch.addIdentity(privateKeyPath, passPhrase);
}else {
jsch.addIdentity(privateKeyPath);
}
sshSession.setConfig("StrictHostKeyChecking", "no");
sshSession.connect();
Channel channel = sshSession.openChannel("sftp");
channel.connect();
sftp = (ChannelSftp) channel;
if (sftp != null && sftp.isConnected()) {
File file = new File(localFileName);
input = new FileInputStream(file);
if(remoteFilePath != null && StringUtils.isNotEmpty(remoteFilePath.trim())) {
if(createDir(sftp, remoteFilePath.trim())) {
sftp.cd(remoteFilePath.trim());
}
}
sftp.put(input, remoteFileName);
sftp.quit();
}
} finally {
if (input != null) {
try {
Closeables.close(input, false);
} finally {
input = null;
}
}
if (sftp != null) {
try {
sftp.disconnect();
} finally {
sftp = null;
}
}
if (sshSession != null) {
try {
sshSession.disconnect();
} finally {
sshSession = null;
}
}
}
}
/**
* 下载文件
*/
public static void download(String user, String ip, int port, String password, String privateKeyPath, String passPhrase, String remoteFileName,
String remoteFilePath, String localFileName) throws Exception {
ChannelSftp sftp = null;
OutputStream output = null;
Session sshSession = null;
try {
JSch jsch = new JSch();
sshSession = jsch.getSession(user, ip, port);
// 判断鉴权方式
if(StringUtils.isNotEmpty(password)) {
sshSession.setPassword(password);
}else if(StringUtils.isNotEmpty(passPhrase)){
jsch.addIdentity(privateKeyPath, passPhrase);
}else {
jsch.addIdentity(privateKeyPath);
}
sshSession.setConfig("StrictHostKeyChecking", "no");
sshSession.connect();
Channel channel = sshSession.openChannel("sftp");
channel.connect();
sftp = (ChannelSftp) channel;
if (sftp != null && sftp.isConnected()) {
if(remoteFilePath != null && StringUtils.isNotEmpty(remoteFilePath.trim())) {
if(createDir(sftp, remoteFilePath.trim())) {
sftp.cd(remoteFilePath.trim());
}
}
output = new FileOutputStream(localFileName, true);
sftp.get(remoteFileName, output);
sftp.quit();
}
} finally {
if (output != null) {
try {
Closeables.close(output, false);
} finally {
output = null;
}
}
if (sftp != null) {
try {
sftp.disconnect();
} finally {
sftp = null;
}
}
if (sshSession != null) {
try {
sshSession.disconnect();
} finally {
sshSession = null;
}
}
}
}
public static void main(String[] args) throws Exception {
//upload("sftpuser", "10.107.97.20", 57001, null, "C:/Users/bijian/Desktop/test/key", "123456", "a.txt", getCurrentDir(), "C:/Users/bijian/Desktop/bijian.txt");
download("sftpuser", "10.107.97.20", 57001, null, "C:/Users/bijian/Desktop/test/key", "123456", "b.txt", getCurrentDir(), "C:/Users/bijian/Desktop/bijian02.txt");
//upload("sftpuser", "10.107.97.20", 57001, "12345678", null, null, "a.txt", getCurrentDir(), "C:/Users/bijian/Desktop/bijian.txt");
download("sftpuser", "10.107.97.20", 57001, "12345678", null, null, "b.txt", getCurrentDir(), "C:/Users/bijian/Desktop/bijian02.txt");
}
}