代码加密

移动开发中遇到的最让人纠结的要属Java、Android和iPhone三个平台加解密不一致的问题。因为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，总不能为Android和iPhone两个客户端各写一套Web Service接口吧？我相信还会有很多朋友为此困惑，在此分享一套3DES加密程序，能够实现Java、Android和iPhone三个平台加解密一致。

首先是JAVA端的加密工具类，它同样适用于Android端，无需任何修改，即可保证Java与Android端的加解密一致，并且中文不会乱码。 
Java代码

1. package org.liuyq.des3;
2. import java.security.Key;
3. import javax.crypto.Cipher;
4. import javax.crypto.SecretKeyFactory;
5. import javax.crypto.spec.DESedeKeySpec;
6. import javax.crypto.spec.IvParameterSpec;
7. /**
8. * 3DES加密工具类
9. */
10. public class Des3 {
11. // 密钥
12. private final static String secretKey = "[email protected]$#365#$";
13. // 向量
14. private final static String iv = "01234567";
15. // 加解密统一使用的编码方式
16. private final static String encoding = "utf-8";
17. /**
18. * 3DES加密
19. *
20. * @param plainText 普通文本
21. * @return
22. * @throws Exception
23. */
24. public static String encode(String plainText) throws Exception {
25. Key deskey = null;
26. DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
27. SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
28. deskey = keyfactory.generateSecret(spec);
29. Cipher cipher = Cipher.getInstance("desede/CBC/PKCS5Padding");
30. IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
31. cipher.init(Cipher.ENCRYPT_MODE, deskey, ips);
32. byte[] encryptData = cipher.doFinal(plainText.getBytes(encoding));
33. return Base64.encode(encryptData);
34. }
35. /**
36. * 3DES解密
37. *
38. * @param encryptText 加密文本
39. * @return
40. * @throws Exception
41. */
42. public static String decode(String encryptText) throws Exception {
43. Key deskey = null;
44. DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
45. SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
46. deskey = keyfactory.generateSecret(spec);
47. Cipher cipher = Cipher.getInstance("desede/CBC/PKCS5Padding");
48. IvParameterSpec ips = new IvParameterSpec(iv.getBytes());
49. cipher.init(Cipher.DECRYPT_MODE, deskey, ips);
50. byte[] decryptData = cipher.doFinal(Base64.decode(encryptText));
51. return new String(decryptData, encoding);
52. }
53. }

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上面的加密工具类会使用到Base64这个类，该类的源代码如下： Java代码

1. import java.io.ByteArrayOutputStream;
2. import java.io.IOException;
3. import java.io.OutputStream;
4. /**
5. * Base64编码工具类
6. */
7. public class Base64 {
8. private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
9. public static String encode(byte[] data) {
10. int start = 0;
11. int len = data.length;
12. StringBuffer buf = new StringBuffer(data.length * 3 / 2);
13. int end = len - 3;
14. int i = start;
15. int n = 0;
16. while (i <= end) {
17. int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff);
18. buf.append(legalChars[(d >> 18) & 63]);
19. buf.append(legalChars[(d >> 12) & 63]);
20. buf.append(legalChars[(d >> 6) & 63]);
21. buf.append(legalChars[d & 63]);
22. i += 3;
23. if (n++ >= 14) {
24. n = 0;
25. buf.append(" ");
26. }
27. }
28. if (i == start + len - 2) {
29. int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);
30. buf.append(legalChars[(d >> 18) & 63]);
31. buf.append(legalChars[(d >> 12) & 63]);
32. buf.append(legalChars[(d >> 6) & 63]);
33. buf.append("=");
34. } else if (i == start + len - 1) {
35. int d = (((int) data[i]) & 0x0ff) << 16;
36. buf.append(legalChars[(d >> 18) & 63]);
37. buf.append(legalChars[(d >> 12) & 63]);
38. buf.append("==");
39. }
40. return buf.toString();
41. }
42. private static int decode(char c) {
43. if (c >= ‘A‘ && c <= ‘Z‘)
44. return ((int) c) - 65;
45. else if (c >= ‘a‘ && c <= ‘z‘)
46. return ((int) c) - 97 + 26;
47. else if (c >= ‘0‘ && c <= ‘9‘)
48. return ((int) c) - 48 + 26 + 26;
49. else
50. switch (c) {
51. case ‘+‘:
52. return 62;
53. case ‘/‘:
54. return 63;
55. case ‘=‘:
56. return 0;
57. default:
58. throw new RuntimeException("unexpected code: " + c);
59. }
60. }
61. /**
62. * Decodes the given Base64 encoded String to a new byte array. The byte array holding the decoded data is returned.
63. */
64. public static byte[] decode(String s) {
65. ByteArrayOutputStream bos = new ByteArrayOutputStream();
66. try {
67. decode(s, bos);
68. } catch (IOException e) {
69. throw new RuntimeException();
70. }
71. byte[] decodedBytes = bos.toByteArray();
72. try {
73. bos.close();
74. bos = null;
75. } catch (IOException ex) {
76. System.err.println("Error while decoding BASE64: " + ex.toString());
77. }
78. return decodedBytes;
79. }
80. private static void decode(String s, OutputStream os) throws IOException {
81. int i = 0;
82. int len = s.length();
83. while (true) {
84. while (i < len && s.charAt(i) <= ‘ ‘)
85. i++;
86. if (i == len)
87. break;
88. int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3)));
89. os.write((tri >> 16) & 255);
90. if (s.charAt(i + 2) == ‘=‘)
91. break;
92. os.write((tri >> 8) & 255);
93. if (s.charAt(i + 3) == ‘=‘)
94. break;
95. os.write(tri & 255);
96. i += 4;
97. }
98. }
99. }

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接下来是iPhone端的加密程序，当然是用Ojbective-C写的3DES加密程序，源代码如下： 
Java代码

1. //
2. //  DES3Util.h
3. //
4. #import <Foundation/Foundation.h>
5. @interface DES3Util : NSObject {
6. }
7. // 加密方法
8. + (NSString*)encrypt:(NSString*)plainText;
9. // 解密方法
10. + (NSString*)decrypt:(NSString*)encryptText;
11. @end

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Java代码

1. //
2. //  DES3Util.m
3. //
4. #import "DES3Util.h"
5. #import <CommonCrypto/CommonCryptor.h>
6. #import "GTMBase64.h"
7. #define gkey                        @"[email protected]$#365#$"
8. #define gIv             @"01234567"
9. @implementation DES3Util
10. // 加密方法
11. + (NSString*)encrypt:(NSString*)plainText {
12. NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
13. size_t plainTextBufferSize = [data length];
14. const void *vplainText = (const void *)[data bytes];
15. CCCryptorStatus ccStatus;
16. uint8_t *bufferPtr = NULL;
17. size_t bufferPtrSize = 0;
18. size_t movedBytes = 0;
19. bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
20. bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
21. memset((void *)bufferPtr, 0x0, bufferPtrSize);
22. const void *vkey = (const void *) [gkey UTF8String];
23. const void *vinitVec = (const void *) [gIv UTF8String];
24. ccStatus = CCCrypt(kCCEncrypt,
25. kCCAlgorithm3DES,
26. kCCOptionPKCS7Padding,
27. vkey,
28. kCCKeySize3DES,
29. vinitVec,
30. vplainText,
31. plainTextBufferSize,
32. (void *)bufferPtr,
33. bufferPtrSize,
34. &movedBytes);
35. NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
36. NSString *result = [GTMBase64 stringByEncodingData:myData];
37. return result;
38. }
39. // 解密方法
40. + (NSString*)decrypt:(NSString*)encryptText {
41. NSData *encryptData = [GTMBase64 decodeData:[encryptText dataUsingEncoding:NSUTF8StringEncoding]];
42. size_t plainTextBufferSize = [encryptData length];
43. const void *vplainText = [encryptData bytes];
44. CCCryptorStatus ccStatus;
45. uint8_t *bufferPtr = NULL;
46. size_t bufferPtrSize = 0;
47. size_t movedBytes = 0;
48. bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
49. bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
50. memset((void *)bufferPtr, 0x0, bufferPtrSize);
51. const void *vkey = (const void *) [gkey UTF8String];
52. const void *vinitVec = (const void *) [gIv UTF8String];
53. ccStatus = CCCrypt(kCCDecrypt,
54. kCCAlgorithm3DES,
55. kCCOptionPKCS7Padding,
56. vkey,
57. kCCKeySize3DES,
58. vinitVec,
59. vplainText,
60. plainTextBufferSize,
61. (void *)bufferPtr,
62. bufferPtrSize,
63. &movedBytes);
64. NSString *result = [[[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)bufferPtr
65. length:(NSUInteger)movedBytes] encoding:NSUTF8StringEncoding] autorelease];
66. return result;
67. }
68. @end

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iPhone端的加密工具类中引入了“GTMBase64.h”，这是iOS平台的Base64编码工具类，就不在这里贴出相关代码了，需要的百度一下就能找到。

这样，JAVA，Android和iPhone三个平台的加密不一致问题就可以解决了。其实，对此问题，还有一种更好的实现方式，那就是用C语言写一套加密程序，这样在iOS平台是可以直接使用C程序的，而在Java和Android端通过JNI去调用C语言编写的加密方法，这样也可以实现3个平台调用同一套加密程序。