fix(crypto): use 12-byte AES-GCM nonce for new seed exports - #4
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adequatelimited wants to merge 1 commit into
Open
fix(crypto): use 12-byte AES-GCM nonce for new seed exports#4adequatelimited wants to merge 1 commit into
adequatelimited wants to merge 1 commit into
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New encryptions now use the standard 96-bit GCM nonce instead of 16 bytes. Decrypt continues to read the IV length from the stored record, so existing 16-byte-IV keystores still decrypt.
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Repo:
adequatesystems/mochimo-wallet· Branch:fix/ar4-gcm-nonce-12→mainAudit finding: AR-4 — AES-GCM used a 16-byte IV instead of the 12-byte standard nonce (Severity: LOW)
What & why
The master-seed AES-GCM encryption generated a 16-byte IV. GCM's standard/recommended nonce is 96 bits (12 bytes); non-standard sizes are internally re-hashed by GCM. Best-practice alignment.
Changes
src/core/MasterSeed.ts—export()now generates a 12-byte random nonce for new encryptions. Decrypt paths (import/importFromDerivedKey) continue to read the IV length from the stored record, so nothing on the read path is hardcoded.test/…— new exports carry a 12-byte IV and round-trip; a synthesized legacy 16-byte-IV blob still decrypts.Backward compatibility
✅ No impact on existing wallets. Old keystores store their own 16-byte IV and decrypt unchanged; only newly written blobs use the 12-byte nonce.
Testing
npx tsc --noEmitclean; MasterSeed suite green including the new legacy-IV decrypt test.Notes for reviewer
Pure best-practice tweak; no security-critical behavior change (the IV was already random and unique per encryption).