How to parse and block of text with no common delimiter?

[nine72]

I have a single data block (encrypted) that is being generated (see example block below). My issue is that there is NO delimiter in the block that I can use as a landmark to break this into only the portions that I need.

Looking at the sample at the bottom of this lets say I need to count from the left 18 places and then pull out the characters 19 to 51 and set as a value. Then move two more places to 53 and pull out 53 to 112 and make that another value etc.

I have looked at explode and some length options but nothing seams to be what I need. Any help or advice would be great (I know it can be done in perl and I have it done but I need to really do it in PHP as well.)

SAMPLE DATA BLOCK

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

[Luuk]

Because substr start counting from 0, untested:

$a = substr($data, 19-1, 51-19+1);
$b = substr($data, 53-1, 112-53+1);
 

[nine72]

I just tried this and i cant believe that it was that easy. I spent a week doing everything I could think of including regx for this. Thank you so much, now maybe i can get this project off my list!

I guess my pic says it all for me on this one lol.