ios des 加密长度的坑

今天在做des加密的时候,在网上找到这段代码 挺好用的,demo测试没什么问题

//加密
-(NSString *)encryptUseDES:(NSString *)plainText andKey:(NSString *)authKey{
    const void *iv  = (const void *) [@"12345678" UTF8String];
    
    NSString *ciphertext = nil;
    
    NSData *textData = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [textData length];
    NSInteger bufferLength = (dataLength/1024 +1)*1024;
    unsigned char buffer[bufferLength];
    memset(buffer, 0, sizeof(char) * bufferLength);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [authKey UTF8String],
                                          kCCKeySizeDES,
                                          iv,
                                          [textData bytes],
                                          dataLength,
                                          buffer,
                                          bufferLength,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted];
        ciphertext = [data base64EncodedStringWithOptions:0];
    }
    return ciphertext;
}

但是当我们加密长度大于1M的数据时 直接崩溃了

image.png

于是查询出来问题出在这里 创建的buffer 无法在内存中分配到足够大的内存

unsigned char buffer[bufferLength];

在大神的指点下换了一个分配方式解决了问题

    unsigned char * buffer = (unsigned  char *)malloc(bufferLength);
    memset(buffer, 0, sizeof(char) * bufferLength);

记得最后释放内存

   free(buffer);

完整代码如下

//加密
-(NSString *)encryptUseDES:(NSString *)plainText andKey:(NSString *)authKey{
    const void *iv  = (const void *) [@"12345678" UTF8String];
    
    NSString *ciphertext = nil;
    
    NSData *textData = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    
    NSUInteger dataLength = [textData length];
    NSInteger bufferLength = (dataLength/1024 +1)*1024;
    //    unsigned char buffer[bufferLength];
    
    unsigned char * buffer = (unsigned  char *)malloc(bufferLength);
    memset(buffer, 0, sizeof(char) * bufferLength);
    size_t numBytesEncrypted = 0;
    
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [authKey UTF8String],
                                          kCCKeySizeDES,
                                          iv,
                                          [textData bytes],
                                          dataLength,
                                          buffer,
                                          bufferLength,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted];
        ciphertext = [data base64EncodedStringWithOptions:0];
    }
    free(buffer);
    return ciphertext;
}