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3DES
3DES（或称为Triple DES）是三重数据加密算法（TDEA，Triple Data Encryption Algorithm）块密码的通称。它相当于是对每个数据块应用三次DES加密算法。由于计算机运算能力的增强，原版DES密码的密钥长度变得容易被暴力破解；3DES即是设计用来提供一种相对简单的方法，即通过增加DES的密钥长度来避免类似的攻击，而不是设计一种全新的块密码算法。
其中，DES( KL[X] )表示用密钥K对数据X进行DES加密，DES-1( KL[Y] )表示用密钥K对数据Y进行解密。
Android、iPhone和Java三个平台一致的加密算法
手机端后台通常是用JAVA开发的Web Service，Android和iPhone客户端调用同样的Web Service接口，为了数据安全考虑，要对数据进行加密。头疼的问题就来了，很难编写出一套加密程序，在3个平台间加解密的结果一致，然而一套3DES加密程序，能够实现Java、Android和iPhone三个平台加解密一 致。
iPhone端的加密程序，OC写的3DES加密程序，源代码如下：
#import <Foundation/Foundation.h>
@interface DES3Util : NSObject
// 加密方法
+ (NSString*)encrypt:(NSString*)plainText;
// 解密方法
+ (NSString*)decrypt:(NSString*)encryptText;
@end //下面的GTMBase64为第三方类，可去git下载，这里代码就不给了
#import "DES3Util.h"
#import <CommonCrypto/CommonCryptor.h>
#import "GTMBase64.h"
#define gkey @"liuyunqiang@lx100$#365#$"
#define gIv @"01234567"
@implementation DES3Util
// 加密方法
+ (NSString*)encrypt:(NSString*)plainText {
NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
size_t plainTextBufferSize = [data length];
const void *vplainText = (const void *)[data bytes];
CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;
bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
memset((void *)bufferPtr, 0x0, bufferPtrSize);
const void *vkey = (const void *) [gkey UTF8String];
const void *vinitVec = (const void *) [gIv UTF8String];
ccStatus = CCCrypt(kCCEncrypt,
kCCAlgorithm3DES,
kCCOptionPKCS7Padding,
vkey,
kCCKeySize3DES,
vinitVec,
vplainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
NSString *result = [GTMBase64 stringByEncodingData:myData];
return result;
}// 解密方法
+ (NSString*)decrypt:(NSString*)encryptText {
NSData *encryptData = [GTMBase64 decodeData:[encryptText dataUsingEncoding:NSUTF8StringEncoding]];
size_t plainTextBufferSize = [encryptData length];
const void *vplainText = [encryptData bytes];
CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;
bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
memset((void *)bufferPtr, 0x0, bufferPtrSize);
const void *vkey = (const void *) [gkey UTF8String];
const void *vinitVec = (const void *) [gIv UTF8String];
ccStatus = CCCrypt(kCCDecrypt,
kCCAlgorithm3DES,
kCCOptionPKCS7Padding,
vkey,
kCCKeySize3DES,
vinitVec,
vplainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
NSString *result = [[[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)bufferPtr
length:(NSUInteger)movedBytes] encoding:NSUTF8StringEncoding] autorelease];
return result;
}
@end
2).Java端的加密工具类，适用于Android端，无需任何修改，即可保证Java与Android端的加密一致，并且中文不会乱码。
package org.liuyq.des3;
import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import javax.crypto.spec.IvParameterSpec;
/**
* 3DES加密工具类
*
* @author liufeng
* @date 2012-10-11
*/
public class Des3 {
// 密钥
private final static String secretKey = "liuyunqiang@lx100$#365#$" ;
// 向量
private final static String iv = "01234567" ;
// 加解密统一使用的编码方式
private final static String encoding = "utf-8" ;
/**
* 3DES加密
*
* @param plainText 普通文本
* @return
* @throws Exception
*/
public static String encode(String plainText) throws Exception {
Key deskey = null ;
DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
SecretKeyFactory keyfactory = SecretKeyFactory.getInstance( "desede" );
deskey = keyfactory.generateSecret(spec);
Cipher cipher = Cipher.getInstance( "desede/CBC/PKCS5Padding" );
IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
cipher.init(Cipher.ENCRYPT_MODE, deskey, ips);
byte [] encryptData = cipher.doFinal(plainText.getBytes(encoding));
return Base64.encode(encryptData);
}
/**
* 3DES解密
*
* @param encryptText 加密文本
* @return
* @throws Exception
*/
public static String decode(String encryptText) throws Exception {
Key deskey = null ;
DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
SecretKeyFactory keyfactory = SecretKeyFactory.getInstance( "desede" );
deskey = keyfactory.generateSecret(spec);
Cipher cipher = Cipher.getInstance( "desede/CBC/PKCS5Padding" );
IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
cipher.init(Cipher.DECRYPT_MODE, deskey, ips);
byte [] decryptData = cipher.doFinal(Base64.decode(encryptText));
return new String(decryptData, encoding);
}
}package org.liuyq.des3;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Base64编码工具类
*
* @author liufeng
* @date 2012-10-11
*/
public class Base64 {
private static final char [] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" .toCharArray();
public static String encode( byte [] data) {
int start = 0 ;
int len = data.length;
StringBuffer buf = new StringBuffer(data.length * 3 / 2 );
int end = len - 3 ;
int i = start;
int n = 0 ;
while (i <= end) {
int d = (((( int ) data[i]) & 0x0ff ) << 16 ) | (((( int ) data[i + 1 ]) & 0x0ff ) << 8 ) | ((( int ) data[i + 2 ]) & 0x0ff );
buf.append(legalChars[(d >> 18 ) & 63 ]);
buf.append(legalChars[(d >> 12 ) & 63 ]);
buf.append(legalChars[(d >> 6 ) & 63 ]);
buf.append(legalChars[d & 63 ]);
i += 3 ;
if (n++ >= 14 ) {
n = 0 ;
buf.append( " " );
}
}
if (i == start + len - 2 ) {
int d = (((( int ) data[i]) & 0x0ff ) << 16 ) | (((( int ) data[i + 1 ]) & 255 ) << 8 );
buf.append(legalChars[(d >> 18 ) & 63 ]);
buf.append(legalChars[(d >> 12 ) & 63 ]);
buf.append(legalChars[(d >> 6 ) & 63 ]);
buf.append( "=" );
} else if (i == start + len - 1 ) {
int d = ((( int ) data[i]) & 0x0ff ) << 16 ;
buf.append(legalChars[(d >> 18 ) & 63 ]);
buf.append(legalChars[(d >> 12 ) & 63 ]);
buf.append( "==" );
}
return buf.toString();
}
private static int decode( char c) {
if (c >= 'A' && c <= 'Z' )
return (( int ) c) - 65 ;
else if (c >= 'a' && c <= 'z' )
return (( int ) c) - 97 + 26 ;
else if (c >= '0' && c <= '9' )
return (( int ) c) - 48 + 26 + 26 ;
else
switch (c) {
case '+' :
return 62 ;
case '/' :
return 63 ;
case '=' :
return 0 ;
default :
throw new RuntimeException( "unexpected code: " + c);
}
}
/**
* Decodes the given Base64 encoded String to a new byte array. The byte array holding the decoded data is returned.
*/
public static byte [] decode(String s) {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
decode(s, bos);
} catch (IOException e) {
throw new RuntimeException();
}
byte [] decodedBytes = bos.toByteArray();
try {
bos.close();
bos = null ;
} catch (IOException ex) {
System.err.println( "Error while decoding BASE64: " + ex.toString());
}
return decodedBytes;
}
private static void decode(String s, OutputStream os) throws IOException {
int i = 0 ;
int len = s.length();
while ( true ) {
while (i < len && s.charAt(i) <= ' ' )
i++;
if (i == len)
break ;
int tri = (decode(s.charAt(i)) << 18 ) + (decode(s.charAt(i + 1 )) << 12 ) + (decode(s.charAt(i + 2 )) << 6 ) + (decode(s.charAt(i + 3 )));
os.write((tri >> 16 ) & 255 );
if (s.charAt(i + 2 ) == '=' )
break ;
os.write((tri >> 8 ) & 255 );
if (s.charAt(i + 3 ) == '=' )
break ;
os.write(tri & 255 );
i += 4 ;
}
}
}参考链接：http://developer.51cto.com/art/201311/419158_all.htm
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