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Can someone clarify how the signing can't be spoofed (or can it)? If we have the source, can't we just use the key to now sign requests from other clients and p
by stavros 7mo ago
Can someone clarify how the signing can't be spoofed (or can it)? If we have the source, can't we just use the key to now sign requests from other clients and pretend they're coming from CC itself?
- MadsRC 7mo agoWhat signing? Are you referencing the use of Claude subscription authentication (oauth) from non-Claude Code clients? That’s already possible, nothing prevents you from doing it. They are detecting it on their backend by profiling your API calls, not by guarding with some secret crypto stuff. At least that’s how things worked last week xD
- stavros 7mo agoI'm referring to this signing bit: https://alex000kim.com/posts/2026-03-31-claude-code-source-leak/#native-client-attestation-below-the-js-runtime https://alex000kim.com/posts/2026-03-31-claude-code-source-l... Ah, it seems that Bun itself signs the code. I don't understand how this can't be spoofed.
- MadsRC 7mo agoAh yes, the API will accept requests that doesn’t include the client attestation (or the fingerprint from src/utils/fingerprint.ts. At least it did a couple of weeks back. They are most likely using these as post-fact indicators and have automation they kicks in after a threshold is reached. Now that the indicators have leaked, they will most likely be rotated.
- Galanwe 7mo ago> Now that the indicators have leaked, they will most likely be rotated. They can't really do that. Now they have no way to distinguish "this is a user of a non updated Claude code" from "this is a user of a Claude code proxy".