Indistinguishability obfuscation (iO)
Encrypting a program so that anyone can run it on plaintext inputs and receive plaintext outputs without learning its internal logic diamond-io. The motivating application is handing someone a package that uses a hidden secret key in some circumstances but not others — the key is inside the program, and the program still runs.
iO is the strong general-purpose primitive of this corner: a great many other constructions follow from it, which is why the field keeps working on it despite the runtime problem below.
The runtime problem is the whole story
The conservative tech tree has a blocking flaw that no feasibility result removes: "literally galactic runtime" — actually running one takes longer than the lifetime of the universe. So iO has been buildable and unusable at the same time, which is the purest example of why concrete-efficiency is a separate question from possibility.
Diamond iO trades safety for speed to reach "planetary, rather than galactic runtime — still infeasible today, but perhaps only a few further optimizations away from becoming a reality at least for a few use cases." It modifies BGG+14 attribute-based encryption, running FHE inside ABE as traditional iO does, but changes the conditional-FHE-decryption mechanism and the input-encoding generation so the result is "just as computationally intensive as functional encryption" rather than a tower on top of it.
Lattice assumptions, and how young they are
Security rests on evasive LWE (Wee22) and all-product LWE, the latter unique to diamond iO. Both are learning-with-errors variants, so this corner of the spoke is lattice-based and post-quantum by construction — a different foundation from the hash-and-code basis of SNARKs like binius and flock, which assume only collision-resistant hashing.
The assumptions are the risk. Evasive LWE is non-falsifiable in Naor's sense, there are known settings where it is false, and diamond iO picks a variant that avoids those. Its own summarizer says more security analysis is needed diamond-io.
Simplicity as a security property
Diamond iO's argued advantage is not only speed but analyzability: no towers of protocols inside protocols, so it can be understood without twenty years of prior constructions. An assumption that nobody can analyze never accumulates the scrutiny that would make it trustworthy, so being followable is part of being safe rather than a courtesy to readers.
Related
diamond-io · concrete-efficiency · succinct-argument · vitalik-buterin · synthesis