Secure Block Building implements cryptographic primitives that protect users from harmful MEV practices during block production. The system encrypts transactions directly in the user's browser with sub-second processing time. SBB utilizes Practical Verifiable Delay Encryption and Single Key Delay Encryption technologies to maintain rollup composability while preventing transaction reordering. The architecture includes slashing mechanisms enforced through native rollup security or shared security protocols. This configuration enables rollups to capture MEV revenue without exposing users to frontrunning or sandwiching attacks.