A few weeks ago, the question came up:

> Is it possible to get files into the STEEM blockchain?

As I have discovered, with a few little tricks you can get everything into the STEEM blockchain.

*The following scripts are for testing purposes and not for productive use*

*I wrote this tutorial for @pcsg-dev, but I don't want to post it with this account for a variety of reasons. I also posted an issue for Steemit and waited some time until it could be reacted to, but it is not taken seriously.*


![bandbreite-computer-daten-1148820.jpg](https://cdn.steemitimages.com/DQmUmN4t6FbSNrQ7B2NxjvScgigK3nP9Komvx4Hsu7iCNfa/bandbreite-computer-daten-1148820.jpg)


### What is needed

- A STEEM account
- One file
- Some know-how in programming
    - Our example scripts are written in PHP

I tried to make the tutorial as simple as possible. 
However, some prerequisites are necessary, so I classify this for experienced users.


### What will you learn:
    
- How to split files with PHP
- How can you upload files to the STEEM blockchain
- How can you reassemble split files with PHP

### Difficulty
- Intermediate


General procedure
------

- We split our file into small pieces
    - This is because STEEM has a maximum length of a post
- We convert each section into text
    - This is because we get binary data only badly in a post
- We write a post / comment for each section 
    - The content of a post is the content of a file
- We read every single post and put all content back together again
    

Tutorial
------

- All examples are written in PHP, but the procedure can be implemented in any language imaginable. 
- Let us take Steemit's white paper as an example.


### Split the file

Splitting the file is easy on the right. 

**Procedure**

- We're looking at the size of the file,
- split the file into many small sections with `fread($file_handle, $buffer)`,
- done

**Partial section Example**


```php
// ...

// how many parts would be existed
$parts = $file_size / $buffer;

// ...

for ($i = 0; $i < $parts; $i++) {
    // read buffer sized amount of the file
    $file_part = fread($file_handle, $buffer);

    // the filename of the part
    $file_part_path = $store_path.$file_name.".part$i";

    // create and write the part
    $file_new = fopen($file_part_path, 'w+');
    fwrite($file_new, $file_part);
    fclose($file_new);
}

// ...

```

You can find the complete example in [split.php](https://github.com/pcsg/steem-tutorials/blob/master/upload-a-file/split.php)


### Upload the file

Here's the interesting part. 
If we now have our small pieces, we have to convert every single piece into text that we can upload as mail.

**Procedure**

- We'll take a section,
- read the contents of the file with `file_get_contents()`,
- convert the binary content to text. For example with `bin2hex()`,
- write a new post with this content

**Example**

```php
// ...

$fileData = bin2hex(file_get_contents('PATH_TO_FILE/steem-whitepaper.pdf.part0'));

// ...
```

You can find the complete example in [upload.php](https://github.com/pcsg/steem-tutorials/blob/master/upload-a-file/upload.php)


### Download the file

For the whole thing to make sense, we have to get the file out of the blockchain.

With the LightRPC Client (https://github.com/hernandev/light-rpc) it is an easy to read single posts via PHP.
If you don't know how to install it, just have a look at https://github.com/hernandev/light-rpc There is a wonderful explanation. 

*If requested, I can also write a small tutorial for you here.*


**Procedure**

- We're reading our summary file,
- get the contents of every post,
- convert this content back to binary data,
- pack all contents into one file.

*In our example file we have moved the download part into a function, so that the whole thing is a bit clearer.*


```php

/**
 * This function fetch a steemit post
 *
 * @param string $username
 * @param string $permlink
 * @return mixed
 */
function getContent($username, $permlink)
{
    $Client = new Client('https://api.steemit.com');

    $Request  = new Request('content_api', 'get_content', [$username, $permlink]);
    $Response = $Client->send($Request);

    if ($Response->isError()) {
        var_dump($Response->error());
        exit;
    }

    $response = $Response->toArray();
    $result   = $response['result'];

    return $result['body'];
}
```


Now, to the "how we get it all together" part.

In our `$summary` we have all our files, we go through them one by one and put our whitepaper 
back into one file.


```php

// now we go through all the files and get the content from the steem blockchain
foreach ($summary as $part => $permlink) {
    echo $part.PHP_EOL;

    // get the content from the steem blockchain with our helper function
    $content = getContent('pscg.test', $permlink);

    // the content is in hex text, but we need binary.
    // if you still remember we converted it for the steem blockchain
    // now we convert it back to binary data
    $content = hex2bin($content);

    // this binary data is now attached to our file
    file_put_contents($filename, $content, \FILE_APPEND);
}
```

You can find the complete example in [download.php](https://github.com/pcsg/steem-tutorials/blob/master/upload-a-file/download.php)


I hope the tutorial was fun and taught you a little bit.

I wish you a lot of fun 
Hen