首先，Java端的DES加密的实现方式，代码如下：
public class DES { private static final byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; public static String encryptDES(String encryptString, String encryptKey) throws Exception { IvParameterSpec zeroIv = new IvParameterSpec(iv); SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES"); Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv); byte[] encryptedData = cipher.doFinal(encryptString.getBytes()); return Base64.encode(encryptedData); }}
上述代码用到了一个Base64的编码类，其代码的实现方式如下：
public class Base64 { private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray(); /** * data[]进行编码 * * @param data * @return */ 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(); }} 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：
/**将二进制转换成16进制 * @param buf * @return String */ public static String parseByte2HexStr(byte buf[]) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < buf.length; i++) { String hex = Integer.toHexString(buf[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } sb.append(hex.toUpperCase()); } return sb.toString(); }
下面是Objective-c在iOS上实现的DES加密算法: 添加头文件#import
- (NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key{ NSString *ciphertext = nil; const char *textBytes = [plainText UTF8String]; NSUInteger dataLength = [plainText length]; unsigned char buffer[1024]; memset(buffer, 0, sizeof(char)); size_t numBytesEncrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, [key UTF8String], kCCKeySizeDES, iv, textBytes, dataLength, buffer, 1024, &numBytesEncrypted); if (cryptStatus == kCCSuccess) { NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted]; ciphertext = [data base64Encoding]; } return ciphertext;}
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。
static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; - (NSString *)base64Encoding; { if (self.length == 0) return @""; char *characters = malloc(self.length*3/2); if (characters == NULL) return @""; int end = self.length - 3; int index = 0; int charCount = 0; int n = 0; while (index <= end) { int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[self bytes])[index + 1]) & 0x0ff) << 8) | ((int)(((char *)[self bytes])[index + 2]) & 0x0ff); characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = encodingTable[(d >> 6) & 63]; characters[charCount++] = encodingTable[d & 63]; index += 3; if(n++ >= 14) { n = 0; characters[charCount++] = ' '; } } if(index == self.length - 2) { int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[self bytes])[index + 1]) & 255) << 8); characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = encodingTable[(d >> 6) & 63]; characters[charCount++] = '='; } else if(index == self.length - 1) { int d = ((int)(((char *)[self bytes])[index]) & 0x0ff) << 16; characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = '='; characters[charCount++] = '='; } NSString * rtnStr = [[NSString alloc] initWithBytesNoCopy:characters length:charCount encoding:NSUTF8StringEncoding freeWhenDone:YES];return rtnStr; } 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：
+(NSString *) parseByte2HexString:(Byte *) bytes { NSMutableString *hexStr = [[NSMutableString alloc]init]; int i = 0; if(bytes) { while (bytes[i] != '\0') { NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数 if([hexByte length]==1) [hexStr appendFormat:@"0%@", hexByte]; else [hexStr appendFormat:@"%@", hexByte]; i++; } } NSLog(@"bytes 的16进制数为:%@",hexStr); return hexStr; } +(NSString *) parseByteArray2HexString:(Byte[]) bytes { NSMutableString *hexStr = [[NSMutableString alloc]init]; int i = 0; if(bytes) { while (bytes[i] != '\0') { NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数 if([hexByte length]==1) [hexStr appendFormat:@"0%@", hexByte]; else [hexStr appendFormat:@"%@", hexByte]; i++; } } NSLog(@"bytes 的16进制数为:%@",hexStr); return hexStr; }
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：
private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; public static String decryptDES(String decryptString, String decryptKey) throws Exception { byte[] byteMi = Base64.decode(decryptString); IvParameterSpec zeroIv = new IvParameterSpec(iv); SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES"); Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); cipher.init(Cipher.DECRYPT_MODE, key, zeroIv); byte decryptedData[] = cipher.doFinal(byteMi); return new String(decryptedData); } Base64的decode方法如下：
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; } } 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); } }
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：
String plaintext = "abcd"; String ciphertext = DES.encryptDES(plaintext, "20120401"); System.out.println("明文：" + plaintext); System.out.println("密钥：" + "20120401"); System.out.println("密文：" + ciphertext); 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：abcdObjective-c端的测试代码如下：
NSString *plaintext = @"abcd"; NSString *ciphertext = [EncryptUtil encryptUseDES:plaintext key:@"20120401"]; NSLog(@"明文：%@",plaintext); NSLog(@"秘钥：%@",@"20120401"); NSLog(@"密文：%@",ciphertext);
输出结果： 2012-04-05 12:00:47.348 TestEncrypt[806:f803] 明文：abcd 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 秘钥：20120401 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 密文：W7HR43/usys=