Double Strength Affine

A slight security upgrade, is it enough?

Discuss The Problem

One of the problems with the Affine Cipher is that the block size is too small. So I remade it with a block size of 2 characters instead of 1. The alphabet is the same:

But now the blocks are 2 characters instead of one, yielding 841 possible blocks instead of 29. The characters are mapped to numbers by their index in the alphabet, and the blocks are mapped to numbers by multiplying the first character's number by 29 and adding the second character's number. So the block BC is mapped to the value 31.

This English text was encrypted with the double strength Affine cipher:

Submit the (lowercase hex) md5 hash of the plain text.