首先，Java端的DES加密的实现方式，代码如下：
public class DES { private static 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:
const Byte iv[] = {1,2,3,4,5,6,7,8};+(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key{ NSString *ciphertext = nil; NSData *textData = [plainText dataUsingEncoding:NSUTF8StringEncoding]; NSUInteger dataLength = [textData length]; unsigned char buffer[1024]; memset(buffer, 0, sizeof(char)); size_t numBytesEncrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, [key UTF8String], kCCKeySizeDES, iv, [textData bytes], dataLength, buffer, 1024, &numBytesEncrypted); if (cryptStatus == kCCSuccess) { NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted]; ciphertext = [Base64 encode:data]; } return ciphertext;} 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。
iOS下的Base64算法在后面 。
JAVA下的解密算法如下：
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); } } Objective-c在下的DES解密算法:
+(NSString *)decryptUseDES:(NSString *)cipherText key:(NSString *)key{ NSString *plaintext = nil; NSData *cipherdata = [Base64 decode:cipherText]; unsigned char buffer[1024]; memset(buffer, 0, sizeof(char)); size_t numBytesDecrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, [key UTF8String], kCCKeySizeDES, iv, [cipherdata bytes], [cipherdata length], buffer, 1024, &numBytesDecrypted); if(cryptStatus == kCCSuccess) { NSData *plaindata = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesDecrypted]; plaintext = [[NSString alloc]initWithData:plaindata encoding:NSUTF8StringEncoding]; } return plaintext;}
下面是objective-c 实现的Base64工具对象，当然你也可以选择使用google的那个Base64类——（功能很强大）,初步测试使用GTMBase64和使用我写的这个Base64效果都是一样的。
static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";@interface Base64()+(int)char2Int:(char)c;@end@implementation Base64+(NSString *)encode:(NSData *)data{ if (data.length == 0) return nil; char *characters = malloc(data.length * 3 / 2); if (characters == NULL) return nil; int end = data.length - 3; int index = 0; int charCount = 0; int n = 0; while (index <= end) { int d = (((int)(((char *)[data bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[data bytes])[index + 1]) & 0x0ff) << 8) | ((int)(((char *)[data 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 == data.length - 2) { int d = (((int)(((char *)[data bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[data 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 == data.length - 1) { int d = ((int)(((char *)[data 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;}+(NSData *)decode:(NSString *)data{ if(data == nil || data.length <= 0) { return nil; } NSMutableData *rtnData = [[NSMutableData alloc]init]; int slen = data.length; int index = 0; while (true) { while (index < slen && [data characterAtIndex:index] <= ' ') { index++; } if (index >= slen || index + 3 >= slen) { break; } int byte = ([self char2Int:[data characterAtIndex:index]] << 18) + ([self char2Int:[data characterAtIndex:index + 1]] << 12) + ([self char2Int:[data characterAtIndex:index + 2]] << 6) + [self char2Int:[data characterAtIndex:index + 3]]; Byte temp1 = (byte >> 16) & 255; [rtnData appendBytes:&temp1 length:1]; if([data characterAtIndex:index + 2] == '=') { break; } Byte temp2 = (byte >> 8) & 255; [rtnData appendBytes:&temp2 length:1]; if([data characterAtIndex:index + 3] == '=') { break; } Byte temp3 = byte & 255; [rtnData appendBytes:&temp3 length:1]; index += 4; } return rtnData;}+(int)char2Int:(char)c{ if (c >= 'A' && c <= 'Z') { return c - 65; } else if (c >= 'a' && c <= 'z') { return c - 97 + 26; } else if (c >= '0' && c <= '9') { return c - 48 + 26 + 26; } else { switch(c) { case '+': return 62; case '/': return 63; case '=': return 0; default: return -1; } }}@end 这个和java端的Base64的是一个算法，只是根据语言的特点不同有少许的改动。
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 = ; NSString *ciphertext = [EncryptUtil encryptUseDES:plaintext key:]; NSLog(,plaintext); NSLog(,); NSLog(,ciphertext);
输出结果：
-- :: TestEncrypt[:f803] 明文：abcd -- :: TestEncrypt[:f803] 秘钥： -- :: TestEncrypt[:f803] 密文：W7HR43/usys=