To make the address cookie more future-proof, use bit packing that allows encoding any arbitrary number (while being more efficient for smaller values).

The proposed packing format is:

• The encoded data is split into 4-bit chunks: F v v v.
• If the first bit (MSB) is 0, this is the last chunk.
• If the MSB is 1, the next chunk is a part of the same number.
• The remaining 3 bits encode the value.
• For chunks beyond the first, the actual value is one greater than what's decoded.
• The sequence is LSB-first, meaning the least significant chunk comes first.
  • Rationale: simplifies encoding and decoding.
• The low half of the byte holds the first chunk, the high half holds the second.
  • Rationale: small integers encode to their own value making debugging easier.

For encoding signed integers, apply a zigzag-like transformation first to convert them into positive integers, then use the above bit-packing scheme to encode the result.

Why 4-bit packing?

• Offers a reasonable compression rate.
• Encoding/decoding is lightweight.
• Two small values (less than 8) fit in a single byte.

A demo/proof-of-concept Python implementation is attached.