OC的DES加密，使与java的Cipher类用DES/CBC/PKCS5Padding方式的加密结果同样

问题说明：

近期用到DES加密，而且要与java的Cipher类加密的结果保持一致。没研究过java的Cliper，但工作中Cipher依据DES/CBC/PKCS5Padding加密方式生成了一个字符串。

比較后发现，此字符串与将OC加密生成的NSData直接用字符串格式化（[NSString stringWithFormat:@"%@",data]）同样。所以就先这么用了。

代码例如以下：

#import "CommonCrypto/CommonCryptor.h"
+ (NSString *)encryptUseDES:(NSString *)plainText andKey:(NSString *)authKey andIv:(NSString *)authIv{
    const void *iv  = (const void *) [authIv UTF8String];
    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,
                                          [authKey UTF8String],
                                          kCCKeySizeDES,
                                          iv,
                                          [textData bytes],
                                          dataLength,
                                          buffer,
                                          1024,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted];
        NSString *oriStr = [NSString stringWithFormat:@"%@",data];
        NSCharacterSet *cSet = [NSCharacterSet characterSetWithCharactersInString:@"< >"];
        ciphertext = [[oriStr componentsSeparatedByCharactersInSet:cSet] componentsJoinedByString:@""];
    }
    return ciphertext;
}