iOS客户端与JAVA服务器之间的RSA加密解密

文章转载自：http://www.cnblogs.com/makemelike/articles/3802518.html　　在网上找了许多篇关于RSA加密解密的文章与博客，是很有帮助，但比较零散与不简洁。　　(至于RSA的基本原理，大家可以看 阮一峰的网络日志 的 RSA算法原理（一） 和 RSA算法原理（二） )　　这篇文章只是做一个整理，帮大家理清一下步骤的而已（ 英文版本请看 RSAEncrypt and Decrypt in IOS and JAVA ）。

一、首先，打开Terminal， 生成必要的公钥、私钥、证书:

openssl genrsa -out private_key.pem 1024

openssl req -new -key private_key.pem -out rsaCertReq.csr

openssl x509 -req -days 3650 -in rsaCertReq.csr -signkey private_key.pem -out rsaCert.crt

openssl x509 -outform der -in rsaCert.crt -out public_key.der　　　　　　　　　　　　　　　// Create public_key.der For IOS

openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt　　// Create private_key.p12 For IOS. 这一步，请记住你输入的密码，IOS代码里会用到

openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout　　　　　　　　　　　　　// Create rsa_public_key.pem For Java
　
openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt　　　　　// Create pkcs8_private_key.pem For Java

12345678910111213上面七个步骤，总共生成7个文件。其中　public_key.der 和 private_key.p12 这对公钥私钥是给IOS用的， rsa_public_key.pem 和 pkcs8_private_key.pem　是给JAVA用的。　　它们的源都来自一个私钥：private_key.pem ， 所以IOS端加密的数据，是可以被JAVA端解密的，反过来也一样。

二、IOS 代码:

　　先请你把 public_key.der 和 private_key.p12 拖进你的Xcode项目里去 ， 也请引入 Security.framework 以及 NSData+Base64.h/m (Download) 到项目里。　　RSAEncryptor.h:　　

#import <Foundation/Foundation.h>

@interface RSAEncryptor : NSObject

#pragma mark - Instance Methods

-(void) loadPublicKeyFromFile: (NSString*) derFilePath;
-(void) loadPublicKeyFromData: (NSData*) derData;

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password;
-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password;

-(NSString*) rsaEncryptString:(NSString*)string;
-(NSData*) rsaEncryptData:(NSData*)data ;

-(NSString*) rsaDecryptString:(NSString*)string;
-(NSData*) rsaDecryptData:(NSData*)data;

#pragma mark - Class Methods

+(void) setSharedInstance: (RSAEncryptor*)instance;
+(RSAEncryptor*) sharedInstance;

@end　　

123456789101112131415161718192021222324252627282930313233RSAEncryptor.m:

#import "RSAEncryptor.h"

#import <Security/Security.h>
#import "NSData+Base64.h"

@implementation RSAEncryptor
{
SecKeyRef publicKey;

SecKeyRef privateKey;
}

-(void)dealloc
{
CFRelease(publicKey);
CFRelease(privateKey);
}

-(SecKeyRef) getPublicKey {
return publicKey;
}

-(SecKeyRef) getPrivateKey {
return privateKey;
}

-(void) loadPublicKeyFromFile: (NSString*) derFilePath
{
NSData *derData = [[NSData alloc] initWithContentsOfFile:derFilePath];
[self loadPublicKeyFromData: derData];
}
-(void) loadPublicKeyFromData: (NSData*) derData
{
publicKey = [self getPublicKeyRefrenceFromeData: derData];
}

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password
{
NSData *p12Data = [NSData dataWithContentsOfFile:p12FilePath];
[self loadPrivateKeyFromData: p12Data password:p12Password];
}

-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password
{
privateKey = [self getPrivateKeyRefrenceFromData: p12Data password: p12Password];
}

#pragma mark - Private Methods

-(SecKeyRef) getPublicKeyRefrenceFromeData: (NSData*)derData
{
SecCertificateRef myCertificate = SecCertificateCreateWithData(kCFAllocatorDefault, (__bridge CFDataRef)derData);
SecPolicyRef myPolicy = SecPolicyCreateBasicX509();
SecTrustRef myTrust;
OSStatus status = SecTrustCreateWithCertificates(myCertificate,myPolicy,&myTrust);
SecTrustResultType trustResult;
if (status == noErr) {
status = SecTrustEvaluate(myTrust, &trustResult);
}
SecKeyRef securityKey = SecTrustCopyPublicKey(myTrust);
CFRelease(myCertificate);
CFRelease(myPolicy);
CFRelease(myTrust);

return securityKey;
}

-(SecKeyRef) getPrivateKeyRefrenceFromData: (NSData*)p12Data password:(NSString*)password
{
SecKeyRef privateKeyRef = NULL;
NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
[options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
if (securityError == noErr && CFArrayGetCount(items) > 0) {
CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
if (securityError != noErr) {
privateKeyRef = NULL;
}
}
CFRelease(items);

return privateKeyRef;
}

#pragma mark - Encrypt

-(NSString*) rsaEncryptString:(NSString*)string {
NSData* data = [string dataUsingEncoding:NSUTF8StringEncoding];
NSData* encryptedData = [self rsaEncryptData: data];
NSString* base64EncryptedString = [encryptedData base64EncodedString];
return base64EncryptedString;
}

// 加密的大小受限于SecKeyEncrypt函数，SecKeyEncrypt要求明文和密钥的长度一致，如果要加密更长的内容，需要把内容按密钥长度分成多份，然后多次调用SecKeyEncrypt来实现
-(NSData*) rsaEncryptData:(NSData*)data {
SecKeyRef key = [self getPublicKey];
size_t cipherBufferSize = SecKeyGetBlockSize(key);
uint8_t *cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));
size_t blockSize = cipherBufferSize - 11;       // 分段加密
size_t blockCount = (size_t)ceil([data length] / (double)blockSize);
NSMutableData *encryptedData = [[NSMutableData alloc] init] ;
for (int i=0; i<blockCount; i++) {
int bufferSize = MIN(blockSize,[data length] - i * blockSize);
NSData *buffer = [data subdataWithRange:NSMakeRange(i * blockSize, bufferSize)];
OSStatus status = SecKeyEncrypt(key, kSecPaddingPKCS1, (const uint8_t *)[buffer bytes], [buffer length], cipherBuffer, &cipherBufferSize);
if (status == noErr){
NSData *encryptedBytes = [[NSData alloc] initWithBytes:(const void *)cipherBuffer length:cipherBufferSize];
[encryptedData appendData:encryptedBytes];
}else{
if (cipherBuffer) {
free(cipherBuffer);
}
return nil;
}
}
if (cipherBuffer){
free(cipherBuffer);
}
return encryptedData;
}

#pragma mark - Decrypt

-(NSString*) rsaDecryptString:(NSString*)string {
NSData* data = [NSData dataFromBase64String: string];
NSData* decryptData = [self rsaDecryptData: data];
NSString* result = [[NSString alloc] initWithData: decryptData encoding:NSUTF8StringEncoding];
return result;
}

-(NSData*) rsaDecryptData:(NSData*)data {
SecKeyRef key = [self getPrivateKey];
size_t cipherLen = [data length];
void *cipher = malloc(cipherLen);
[data getBytes:cipher length:cipherLen];
size_t plainLen = SecKeyGetBlockSize(key) - 12;
void *plain = malloc(plainLen);
OSStatus status = SecKeyDecrypt(key, kSecPaddingPKCS1, cipher, cipherLen, plain, &plainLen);

if (status != noErr) {
return nil;
}

NSData *decryptedData = [[NSData alloc] initWithBytes:(const void *)plain length:plainLen];

return decryptedData;
}

#pragma mark - Class Methods

static RSAEncryptor* sharedInstance = nil;

+(void) setSharedInstance: (RSAEncryptor*)instance
{
sharedInstance = instance;
}

+(RSAEncryptor*) sharedInstance
{
return sharedInstance;
}

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186　好了，那么，我们就可以在main.m里做个测试了:　　main.m:

#import "AppDelegate.h"
#import "RSAEncryptor.h"

int main(int argc, char *argv[])
{
@autoreleasepool {

RSAEncryptor* rsaEncryptor = [[RSAEncryptor alloc] init];
NSString* publicKeyPath = [[NSBundle mainBundle] pathForResource:@"public_key" ofType:@"der"];
NSString* privateKeyPath = [[NSBundle mainBundle] pathForResource:@"private_key" ofType:@"p12"];
[rsaEncryptor loadPublicKeyFromFile: publicKeyPath];
[rsaEncryptor loadPrivateKeyFromFile: privateKeyPath password:@"ISAACS"];    // 这里，请换成你生成p12时的密码

NSString* restrinBASE64STRING = [rsaEncryptor rsaEncryptString:@"I.O.S"];
NSLog(@"Encrypted: %@", restrinBASE64STRING);       // 请把这段字符串Copy到JAVA这边main()里做测试
NSString* decryptString = [rsaEncryptor rsaDecryptString: restrinBASE64STRING];
NSLog(@"Decrypted: %@", decryptString);

// System.out.println the encrypt string from Java , and paste it here
// 这里请换成你的JAVA这边产生的加密的Base64 Encode的字符串
//        NSString* rsaEncrypyBase64 = [NSString stringWithFormat:@"%@\r%@\r%@",
//                                      @"ZNKCVpFYd4Oi2pecLhDXHh+8kWltUMLdBIBDeTvU5kWpTQ8cA1Y+7wKO3d/M8bhULYf1FhWt80Cg",
//                                      @"7e73SV5r+wSlgGWBvTIxqgTWFS4ELGzsEJpVVSlK1oXF0N2mugOURUILjeQrwn1QTcVdXXTMQ0wj",
//                                      @"50GNwnHbAwyLvsY5EUY="];
//
//        NSString* resultString = [rsaEncryptor rsaDecryptString: rsaEncrypyBase64];
//        NSLog(@"Decrypt Java RSA String: %@", resultString);

return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}

12345678910111213141516171819202122232425262728293031323334　代码里注意请把密码修改换成你的p12密码。　　在main.m的main()函数里有几行注释了的代码，因为那个 ‘rsaEncrypyBase64’ 是我在JAVA端用我的公钥私钥生成的，不适合你的公钥私钥，所以我注释掉。待会做完下面JAVA的，你用你在JAVA端生成的加密字符串替换‘rsaEncrypyBase64’的值，打开注释来测试 JAVA端加密的数据能不能被IOS这端来 解密。(答案是能的)

三、 JAVA 代码：

　　RSAEncryptor.java：

package com.modules.Encryptor;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
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 java.util.ArrayList;
import java.util.List;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class RSAEncryptor {

public static void main(String[] args){

String privateKeyPath = "/Users/Isaacs/Desktop/RSA_KEYS/rsa_public_key.pem";        // replace your public key path here
String publicKeyPath =  "/Users/Isaacs/Desktop/RSA_KEYS/pkcs8_private_key.pem";     // replace your private path here
RSAEncryptor rsaEncryptor = new RSAEncryptor(privateKeyPath, publicKeyPath);

try {

String test = "JAVA";
String testRSAEnWith64 = rsaEncryptor.encryptWithBase64(test);
String testRSADeWith64 = rsaEncryptor.decryptWithBase64(testRSAEnWith64);
System.out.println("\nEncrypt: \n" + testRSAEnWith64);
System.out.println("\nDecrypt: \n" + testRSADeWith64);

// NSLog the encrypt string from Xcode , and paste it here.
// 请粘贴来自IOS端加密后的字符串
//            String rsaBase46StringFromIOS =
//                    "nIIV7fVsHe8QquUbciMYbbumoMtbBuLsCr2yMB/WAhm+S/kGRPlf+k2GH8imZIYQ" + "\r" +
//                    "QBDssVLQmS392QlxS87hnwMRJIzWw6vdRv/k79TgTfu6tI/9QTqIOvNlQIqtIcVm" + "\r" +
//                    "R/suvydoymKgdlB+ce5/tHSxfqEOLLrL1Zl2PqJSP4A=";
//
//            String decryptStringFromIOS = rsaEncryptor.decryptWithBase64(rsaBase46StringFromIOS);
//            System.out.println("Decrypt result from ios client: \n" + decryptStringFromIOS);

} catch (Exception e) {
e.printStackTrace();
}

}

/**
* @param publicKeyFilePath
* @param privateKeyFilePath
*/
public RSAEncryptor(String publicKeyFilePath, String privateKeyFilePath) throws Exception {
String public_key = getKeyFromFile(publicKeyFilePath);
String private_key = getKeyFromFile(privateKeyFilePath);
loadPublicKey(public_key);
loadPrivateKey(private_key);
}
public RSAEncryptor() {
// load the PublicKey and PrivateKey manually
}

public String getKeyFromFile(String filePath) throws Exception {
BufferedReader bufferedReader = new BufferedReader(new FileReader(filePath));

String line = null;
List<String> list = new ArrayList<String>();
while ((line = bufferedReader.readLine()) != null){
list.add(line);
}

// remove the firt line and last line
StringBuilder stringBuilder = new StringBuilder();
for (int i = 1; i < list.size() - 1; i++) {
stringBuilder.append(list.get(i)).append("\r");
}

String key = stringBuilder.toString();
return key;
}

public String decryptWithBase64(String base64String) throws Exception {
//  http://commons.apache.org/proper/commons-codec/ : org.apache.commons.codec.binary.Base64
// sun.misc.BASE64Decoder
byte[] binaryData = decrypt(getPrivateKey(), new BASE64Decoder().decodeBuffer(base64String) /*org.apache.commons.codec.binary.Base64.decodeBase64(base46String.getBytes())*/);
String string = new String(binaryData);
return string;
}

public String encryptWithBase64(String string) throws Exception {
//  http://commons.apache.org/proper/commons-codec/ : org.apache.commons.codec.binary.Base64
// sun.misc.BASE64Encoder
byte[] binaryData = encrypt(getPublicKey(), string.getBytes());
String base64String = new BASE64Encoder().encodeBuffer(binaryData) /* org.apache.commons.codec.binary.Base64.encodeBase64(binaryData) */;
return base64String;
}

// convenient properties
public static RSAEncryptor sharedInstance = null;
public static void setSharedInstance (RSAEncryptor rsaEncryptor) {
sharedInstance = rsaEncryptor;
}

// From: http://blog.csdn.net/chaijunkun/article/details/7275632 
/**
* 私钥
*/
private RSAPrivateKey privateKey;

/**
* 公钥
*/
private RSAPublicKey publicKey;

/**
* 获取私钥
* @return 当前的私钥对象
*/
public RSAPrivateKey getPrivateKey() {
return privateKey;
}

/**
* 获取公钥
* @return 当前的公钥对象
*/
public RSAPublicKey getPublicKey() {
return publicKey;
}

/**
* 随机生成密钥对
*/
public void genKeyPair(){
KeyPairGenerator keyPairGen= null;
try {
keyPairGen= KeyPairGenerator.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
keyPairGen.initialize(1024, new SecureRandom());
KeyPair keyPair= keyPairGen.generateKeyPair();
this.privateKey= (RSAPrivateKey) keyPair.getPrivate();
this.publicKey= (RSAPublicKey) keyPair.getPublic();
}

/**
* 从文件中输入流中加载公钥
* @param in 公钥输入流
* @throws Exception 加载公钥时产生的异常
*/
public void loadPublicKey(InputStream in) throws Exception{
try {
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');
}
}
loadPublicKey(sb.toString());
} catch (IOException e) {
throw new Exception("公钥数据流读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥输入流为空");
}
}

/**
* 从字符串中加载公钥
* @param publicKeyStr 公钥数据字符串
* @throws Exception 加载公钥时产生的异常
*/
public void loadPublicKey(String publicKeyStr) throws Exception{
try {
BASE64Decoder base64Decoder= new BASE64Decoder();
byte[] buffer= base64Decoder.decodeBuffer(publicKeyStr);
KeyFactory keyFactory= KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec= new X509EncodedKeySpec(buffer);
this.publicKey= (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公钥非法");
} catch (IOException e) {
throw new Exception("公钥数据内容读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥数据为空");
}
}

/**
* 从文件中加载私钥
* @param keyFileName 私钥文件名
* @return 是否成功
* @throws Exception
*/
public void loadPrivateKey(InputStream in) throws Exception{
try {
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');
}
}
loadPrivateKey(sb.toString());
} catch (IOException e) {
throw new Exception("私钥数据读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥输入流为空");
}
}

public void loadPrivateKey(String privateKeyStr) throws Exception{
try {
BASE64Decoder base64Decoder= new BASE64Decoder();
byte[] buffer= base64Decoder.decodeBuffer(privateKeyStr);
PKCS8EncodedKeySpec keySpec= new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory= KeyFactory.getInstance("RSA");
this.privateKey= (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
e.printStackTrace();
throw new Exception("私钥非法");
} catch (IOException e) {
throw new Exception("私钥数据内容读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥数据为空");
}
}

/**
* 加密过程
* @param publicKey 公钥
* @param plainTextData 明文数据
* @return
* @throws Exception 加密过程中的异常信息
*/
public byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData) throws Exception{
if(publicKey== null){
throw new Exception("加密公钥为空, 请设置");
}
Cipher cipher= null;
try {
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("无此加密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
}catch (InvalidKeyException e) {
throw new Exception("加密公钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("明文长度非法");
} catch (BadPaddingException e) {
throw new Exception("明文数据已损坏");
}
}

/**
* 解密过程
* @param privateKey 私钥
* @param cipherData 密文数据
* @return 明文
* @throws Exception 解密过程中的异常信息
*/
public byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData) throws Exception{
if (privateKey== null){
throw new Exception("解密私钥为空, 请设置");
}
Cipher cipher= null;
try {
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("无此解密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
}catch (InvalidKeyException e) {
throw new Exception("解密私钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("密文长度非法");
} catch (BadPaddingException e) {
throw new Exception("密文数据已损坏");
}
}

/**
* 字节数据转字符串专用集合
*/
private static final char[] HEX_CHAR= {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

/**
* 字节数据转十六进制字符串
* @param data 输入数据
* @return 十六进制内容
*/
public static String byteArrayToString(byte[] data){
StringBuilder stringBuilder= new StringBuilder();
for (int i=0; i<data.length; i++){
//取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
stringBuilder.append(HEX_CHAR[(data[i] & 0xf0)>>> 4]);
//取出字节的低四位 作为索引得到相应的十六进制标识符
stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
if (i<data.length-1){
stringBuilder.append(' ');
}
}
return stringBuilder.toString();
}

｝

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356　同样的，main()函数里有几行注释了的代码，打开注释， 请复制上面IOS端的加密字符串来替换掉，这样，来测试一下来自IOS端的加密数据能不能被JAVA端解密。(答案也是能的)转载者注： 由于环境的原因没有测试客户端与服务器之间是否可以加密解密成功。仅测试iOS端本地可以将加密以后的字符串进行解密是可以的。