To create one-way compressed block cipher, proceed as follows:
1. Create Stitie Space (part of it can be used, for example 8 x 9 x 12 nodes for 864 bits).
2. Assign mathematical function, complex or not, at each node (use 'strategy' pattern).
3. Partition Stitie Space somehow, and compress 3D Block Cipher that is Stitie Space by joining functions at nodes somehow (for example by substituting variable for a function that computes it, taken from another node). This step can be repeated as many times as neccessary for security.
Private key is such Stitie Space and a secret that decides how Stitie Space is partitioned, and how functions at nodes are joined. It can be determined somehow, more or less randomly or not. Please note that each of blocks can be encrypted little differently, for example by adding encrypted byte number to encrypted byte.
Please note that such private key can be serialized (reduced to a number or color).
Please also note that functions used can depend both on key and plaintext data.