关于 Des加密(Android与ios 与后台java服务器之间的加密解密)
http://blog.sina.com.cn/s/blog_7c8dc2d50101id91.html
(2013-04-17 11:47:23)
分类: iPhone开发 |
最近做了一个移动项目,是有服务器和客户端类型的项目,客户端是要登录才行的,登录的密码要用DES加密,服务器是用Java开发的,客户端要同时支持多平台(Android、iOS),在处理iOS的DES加密的时候遇到了一些问题,起初怎么调都调不成和Android端生成的密文相同。最终一个忽然的想法让我找到了问题的所在,现在将代码总结一下,以备自己以后查阅。
首先,Java端的DES加密的实现方式,代码如下:
1 public class DES { 2 private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; 3 4 public static String encryptDES(String encryptString, String encryptKey) 5 throws Exception { 6 IvParameterSpec zeroIv = new IvParameterSpec(iv); 7 SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES"); 8 Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); 9 cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv); 10 byte[] encryptedData = cipher.doFinal(encryptString.getBytes()); 11 return Base64.encode(encryptedData); 12 } 13 }
上述代码用到了一个Base64的编码类,其代码的实现方式如下:
1 public class Base64 { 2 private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" 3 .toCharArray(); 4 5 11 public static String encode(byte[] data) { 12 int start = 0; 13 int len = data.length; 14 StringBuffer buf = new StringBuffer(data.length * 3 / 2); 15 16 int end = len - 3; 17 int i = start; 18 int n = 0; 19 20 while (i <= end) { 21 int d = ((((int) data[i]) & 0x0ff) << 16) 22 | ((((int) data[i + 1]) & 0x0ff) << 8) 23 | (((int) data[i + 2]) & 0x0ff); 24 25 buf.append(legalChars[(d >> 18) & 63]); 26 buf.append(legalChars[(d >> 12) & 63]); 27 buf.append(legalChars[(d >> 6) & 63]); 28 buf.append(legalChars[d & 63]); 29 30 i += 3; 31 32 if (n++ >= 14) { 33 n = 0; 34 buf.append(" "); 35 } 36 } 37 38 if (i == start + len - 2) { 39 int d = ((((int) data[i]) & 0x0ff) << 16) 40 | ((((int) data[i + 1]) & 255) << 8); 41 42 buf.append(legalChars[(d >> 18) & 63]); 43 buf.append(legalChars[(d >> 12) & 63]); 44 buf.append(legalChars[(d >> 6) & 63]); 45 buf.append("="); 46 } else if (i == start + len - 1) { 47 int d = (((int) data[i]) & 0x0ff) << 16; 48 49 buf.append(legalChars[(d >> 18) & 63]); 50 buf.append(legalChars[(d >> 12) & 63]); 51 buf.append("=="); 52 } 53 54 return buf.toString(); 55 } 56 }
以上便是Java端的DES加密方法的全部实现过程。
我还编写了一个将byte的二进制转换成16进制的方法,以便调试的时候使用打印输出加密后的byte数组的内容,这个方法不是加密的部分,只是为调试而使用的:
1 5 public static String parseByte2HexStr(byte buf[]) { 6 StringBuffer sb = new StringBuffer(); 7 for (int i = 0; i < buf.length; i++) { 8 String hex = Integer.toHexString(buf[i] & 0xFF); 9 if (hex.length() == 1) { 10 hex = ‘0‘ + hex; 11 } 12 sb.append(hex.toUpperCase()); 13 } 14 return sb.toString(); 15 }
下面是Objective-c在iOS上实现的DES加密算法:
1 static Byte iv[] = {1,2,3,4,5,6,7,8}; 2 +(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key 3 { 4 NSString *ciphertext = nil; 5 const char *textBytes = [plainText UTF8String]; 6 NSUInteger dataLength = [plainText length]; 7 unsigned char buffer[1024]; 8 memset(buffer, 0, sizeof(char)); 9 size_t numBytesEncrypted = 0; 10 CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES, 11 kCCOptionPKCS7Padding, 12 [key UTF8String], kCCKeySizeDES, 13 iv, 14 textBytes, dataLength, 15 buffer, 1024, 16 &numBytesEncrypted); 17 if (cryptStatus == kCCSuccess) { 18 NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted]; 19 ciphertext = [data base64Encoding]; 20 } 21 return ciphertext; 22 }
下面是一个关键的类:NSData的Category实现,关于Category的实现网上很多说明不再讲述。
1 static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 2 - (NSString *)base64Encoding; 3 { 4 if (self.length == 0) 5 return @""; 6 7 char *characters = malloc(self.length*3/2); 8 9 if (characters == NULL) 10 return @""; 11 12 int end = self.length - 3; 13 int index = 0; 14 int charCount = 0; 15 int n = 0; 16 17 while (index <= end) { 18 int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) 19 | (((int)(((char *)[self bytes])[index + 1]) & 0x0ff) << 8) 20 | ((int)(((char *)[self bytes])[index + 2]) & 0x0ff); 21 22 characters[charCount++] = encodingTable[(d >> 18) & 63]; 23 characters[charCount++] = encodingTable[(d >> 12) & 63]; 24 characters[charCount++] = encodingTable[(d >> 6) & 63]; 25 characters[charCount++] = encodingTable[d & 63]; 26 27 index += 3; 28 29 if(n++ >= 14) 30 { 31 n = 0; 32 characters[charCount++] = ‘ ‘; 33 } 34 } 35 36 if(index == self.length - 2) 37 { 38 int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) 39 | (((int)(((char *)[self bytes])[index + 1]) & 255) << 8); 40 characters[charCount++] = encodingTable[(d >> 18) & 63]; 41 characters[charCount++] = encodingTable[(d >> 12) & 63]; 42 characters[charCount++] = encodingTable[(d >> 6) & 63]; 43 characters[charCount++] = ‘=‘; 44 } 45 else if(index == self.length - 1) 46 { 47 int d = ((int)(((char *)[self bytes])[index]) & 0x0ff) << 16; 48 characters[charCount++] = encodingTable[(d >> 18) & 63]; 49 characters[charCount++] = encodingTable[(d >> 12) & 63]; 50 characters[charCount++] = ‘=‘; 51 characters[charCount++] = ‘=‘; 52 } 53 NSString * rtnStr = [[NSString alloc] initWithBytesNoCopy:characters length:charCount encoding:NSUTF8StringEncoding freeWhenDone:YES]; 54 return rtnStr; 55 }
这个方法和java端的那个Base64的encode方法基本上是一个算法,只是根据语言的特点不同有少许的改动。
下面也是Objective-c的一个二进制转换为16进制的方法,也是为了测试方便查看写的:
1 +(NSString *) parseByte2HexString:(Byte *) bytes 2 { 3 NSMutableString *hexStr = [[NSMutableString alloc]init]; 4 int i = 0; 5 if(bytes) 6 { 7 while (bytes[i] != ‘\0‘) 8 { 9 NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数10 if([hexByte length]==1) 11 [hexStr appendFormat:@"0%@", hexByte]; 12 else 13 [hexStr appendFormat:@"%@", hexByte]; 14 15 i++; 16 } 17 } 18 NSLog(@"bytes 的16进制数为:%@",hexStr); 19 return hexStr; 20 } 21 22 +(NSString *) parseByteArray2HexString:(Byte[]) bytes 23 { 24 NSMutableString *hexStr = [[NSMutableString alloc]init]; 25 int i = 0; 26 if(bytes) 27 { 28 while (bytes[i] != ‘\0‘) 29 { 30 NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数31 if([hexByte length]==1) 32 [hexStr appendFormat:@"0%@", hexByte]; 33 else 34 [hexStr appendFormat:@"%@", hexByte]; 35 36 i++; 37 } 38 } 39 NSLog(@"bytes 的16进制数为:%@",hexStr); 40 return hexStr; 41 }
以上的加密方法所在的包是CommonCrypto/CommonCryptor.h。
以上便实现了Objective-c和Java下在相同的明文和密钥的情况下生成相同明文的算法。
Base64的算法可以用你们自己写的那个,不一定必须使用我提供的这个。解密的时候还要用Base64进行密文的转换。
我的解密算法如下:
1 private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; 2 public static String decryptDES(String decryptString, String decryptKey) 3 throws Exception { 4 byte[] byteMi = Base64.decode(decryptString); 5 IvParameterSpec zeroIv = new IvParameterSpec(iv); 6 SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES"); 7 Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); 8 cipher.init(Cipher.DECRYPT_MODE, key, zeroIv); 9 byte decryptedData[] = cipher.doFinal(byteMi); 10 11 return new String(decryptedData); 12 }
Base64的decode方法如下:
1 public static byte[] decode(String s) { 2 3 ByteArrayOutputStream bos = new ByteArrayOutputStream(); 4 try { 5 decode(s, bos); 6 } catch (IOException e) { 7 throw new RuntimeException(); 8 } 9 byte[] decodedBytes = bos.toByteArray(); 10 try { 11 bos.close(); 12 bos = null; 13 } catch (IOException ex) { 14 System.err.println("Error while decoding BASE64: " + ex.toString()); 15 } 16 return decodedBytes; 17 } 18 private static void decode(String s, OutputStream os) throws IOException { 19 int i = 0; 20 21 int len = s.length(); 22 23 while (true) { 24 while (i < len && s.charAt(i) <= ‘ ‘) 25 i++; 26 27 if (i == len) 28 break; 29 30 int tri = (decode(s.charAt(i)) << 18) 31 + (decode(s.charAt(i + 1)) << 12) 32 + (decode(s.charAt(i + 2)) << 6) 33 + (decode(s.charAt(i + 3))); 34 35 os.write((tri >> 16) & 255); 36 if (s.charAt(i + 2) == ‘=‘) 37 break; 38 os.write((tri >> 8) & 255); 39 if (s.charAt(i + 3) == ‘=‘) 40 break; 41 os.write(tri & 255); 42 43 i += 4; 44 } 45 } 46 private static int decode(char c) { 47 if (c >= ‘A‘ && c <= ‘Z‘) 48 return ((int) c) - 65; 49 else if (c >= ‘a‘ && c <= ‘z‘) 50 return ((int) c) - 97 + 26; 51 else if (c >= ‘0‘ && c <= ‘9‘) 52 return ((int) c) - 48 + 26 + 26; 53 else 54 switch (c) { 55 case ‘+‘: 56 return 62; 57 case ‘/‘: 58 return 63; 59 case ‘=‘: 60 return 0; 61 default: 62 throw new RuntimeException("unexpected code: " + c); 63 } 64 }
以上便实现了DES加密后的密文的解密。
Java端的测试代码如下:
1 String plaintext = "abcd"; 2 String ciphertext = DES.encryptDES(plaintext, "20120401"); 3 System.out.println("明文:" + plaintext); 4 System.out.println("密钥:" + "20120401"); 5 System.out.println("密文:" + ciphertext); 6 System.out.println("解密后:" + DES.decryptDES(ciphertext, "20120401"));
输出结果:
明文:abcd 密钥:20120401 密文:W7HR43/usys= 解密后:abcd
Objective-c端的测试代码如下:
1 NSString *plaintext = @"abcd"; 2 NSString *ciphertext = [EncryptUtil encryptUseDES:plaintext key:@"20120401"]; 3 NSLog(@"明文:%@",plaintext); 4 NSLog(@"秘钥:%@",@"20120401"); 5 NSLog(@"密文:%@",ciphertext);
输出结果:
1 2012-04-05 12:00:47.348 TestEncrypt[806:f803] 明文:abcd 2 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 秘钥:20120401 3 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 密文:W7HR43/usys=
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