https://leviathan.3xi.club

made a little demo site for my crypto lib. web file encryption, chat, and cli tools

shoutout to bunjs! these single-file executable bins are so hype! watch me install my new crypto lib and build the cli tool in under 0.1s, then watch my demo tool use XChaCha20Poly1305 to encrypt and decrypt a 1gb file in 2s ;D

typescript and wasm in the shell? yes indeed.

https://github.com/xero/leviathan-crypto

been doing biclique cryptographic attack research.

theorem: the time-data trade off moving away from the ciphertext is never favorable. each step away (K31,K30,K29) trades ~2-4 bits of time complexity for 12-40 bits of data complexity.

imho: a 40-bit data penalty to buy 0.06 bits of time is not a tradeoff anyone would ever make.

K31 is uniquely necessary — not just optimal. The data complexity progression from K29 (min 2^{56}) through K30 (min 2^{16}) to K31 (fixed 2^{4}) demonstrates a monotonic structural constraint tied to the biclique construction. Each key schedule step between the delta key index and the biclique states introduces active S-boxes that demand exponentially more chosen plaintexts. K31/K32 are the subkeys applied directly in the biclique states (#91–#96), eliminating propagation entirely. No delta key index other than K31 achieves data complexity within practical reach. The paper's choice of K31 was not arbitrary, it seems the only viable option.

K17 actually outperforms K18 as the nabla pair, a new finding not in the published papers. The prior joint search was restricted to K18 only and could not discover this improvement. K17 produces 8 fewer recomputation S-boxes than K18 at the optimal biclique configuration (1041 vs 1049).

The universal optimality of K17/K18 across all three delta indices, with the separation |delta−17| increasing by exactly 1 per index step (12, 13, 14), points to a fixed structural feature of the Serpent key schedule. the recurrence w[i] = (w[i-8] ^ w[i-5] ^ w[i-3] ^ w[i-1] ^ phi ^ i) <<< 11 produces optimal cancellation properties when the nabla difference enters at K17.