fix(sdk): clear SonarQube ReDoS hotspot in base64url encode#62
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…+ S7781)
SonarQube flagged `/=+$/` in encode() as a slow-regex hotspot (S5852,
ReDoS/CWE-1333). It only ran on btoa() output where `=` is at most 2 trailing
padding chars, so the quadratic input was unreachable — but rather than dismiss
it, remove the regex entirely: convert all the global-regex replaces in encode()
and decode() to replaceAll() with string literals (ES2022 target). This also
satisfies S7781 ("prefer replaceAll over replace"), keeps the transforms linear
and non-backtracking, and is more readable.
Behavior-preserving: base64 only emits `=` as trailing padding, so stripping all
`=` equals stripping the trailing run; the rest are exact equivalents. Output is
byte-identical and the full vitest round-trip suite (76 tests) and tsc pass.
Refs #60
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Resolves the single SonarQube security hotspot on the browser SDK (
codeheadsystems_passkeys-browser).The hotspot
typescript:S5852— slow regular expression / ReDoS (category DoS, CWE-400/CWE-1333).clients/passkeys-browser/src/base64url.ts:18— the/=+$/padding stripper inencode().Why it was effectively safe
The regex only runs on
btoa()output, where=appears solely as 0–2 trailing padding characters (never interior). The catastrophic/quadratic input S5852 warns about — a long run of=followed by a non-matching char — is therefore unreachable, and the input is the host's own bounded bytes, not attacker-controlled.The fix (clear it at the source rather than dismiss it)
Since
=only ever appears as trailing padding in base64, removing all=is equivalent to stripping a trailing run, and/=/gis a single-character, non-backtracking match:Byte-identical output; the full vitest suite (76 tests, incl. base64url round-trips) passes. This removes the finding at the root so it can't reappear on a future scan — no manual "mark Safe" sign-off needed.
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