Claude Weekly Roundup: NIST Curve Origins Discovered, Code Review GA, and Opus 5.5 Fast Mode

NIST ECDSA Curve Origins

Anthropic's Frontier Red Team used Claude to determine that the seeds for NIST P-192 through P-521 curves were generated by the C lrand48 function using Unix timestamps from May 1997 to April 1998. The team found that the P-256 seed was the 1,842nd candidate in this sequence. Anthropic clarified that this discovery does not constitute a security break but makes the existence of a backdoor less plausible. ISRG received a $36,864 bounty for the finding.

Claude Code Review GA and Internal Metrics

Claude Code Review is now generally available for Team and Enterprise plans, with most reviews completing in 6–10 minutes (3x faster than the preview). Admins can select Quick, Standard, or Deep review modes per repository. Internally, the Claude Code team reported that Claude writes approximately 90% of Claude Code's code. From June to September, merged pull requests doubled while the revert rate fell by more than 40%, with agents handling most code reading and a classifier determining human approval needs.

Opus 5.5 Fast Mode and Torvalds' Usage

Opus 5.5 fast mode is out of research preview for all API customers, offering up to 2.5x faster output at $8/$40 per million input/output tokens. Users can enable it by setting speed: "fast" without a beta header. Separately, Linus Torvalds used Claude Code for a Linux kernel patch, noting in the commit message that the code and tests were generated by the assistant under his direction.