WHAT'S CCH? REVERSE ENGINEERING CLAUDE CODE'S REQUEST SIGNING

Summary from the TLDR Dev newsletter

Anthropic's Claude Code client uses a "cch" hash for request signing, which researchers discovered is an xxHash64 of the request body computed within a custom native Bun runtime. This mechanism serves as a non-cryptographic attribution and metering tool to make sure requests originate from official clients rather than acting as a security boundary.