tlock: harden hex helpers and add seal/open input validation

[karagozemin]

fromHex currently decodes each byte with parseInt(..., 16), which silently turns non-hex input into NaN-mangled bytes instead of failing. Add strict hex validation (and an exported isValidHex helper) so malformed hex fails loudly.

Also add guard clauses to sealBid (reject a non-positive Drand round) and openBid (reject an empty ciphertext) so callers get clear errors instead of obscure downstream failures.

[OTimileyin]

Hi Maintainer could you please assign me this issue?

[fadesany]

Hi, I'd like to take on this issue.

I've reviewed the current hex decoding and bid sealing/opening flow. My approach would be to add strict hex validation with an exported isValidHex helper, ensuring malformed or invalid-length input fails before decoding, while adding clear guard clauses for invalid Drand rounds and empty ciphertexts.

I'll also add focused tests covering:

• Valid hex decoding
• Malformed and non-hex input rejection
• Invalid hex length handling
• isValidHex behavior
• Non-positive Drand round rejection in sealBid
• Empty ciphertext rejection in openBid
• Existing valid seal/open flows remaining unchanged

I'll verify the full test suite and CI remain green before opening the PR.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #191)
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[s6pa1rta3n-lab]

/try

I am working on a fix for this issue. Approach:

1. Hex Helpers: Implement and export in and to strictly validate hexadecimal strings (with optional 0x/0X prefix, even length, valid hex characters). Harden fromHex to throw descriptive errors on odd length or invalid characters.
2. Seal / Open Input Validation: Add explicit guard clauses in packages/tlock/src/seal.ts for sealBid (rejecting non-positive/non-integer rounds and invalid nonce lengths) and openBid (rejecting empty ciphertexts).
3. Comprehensive Unit Tests: Add test suites in commitment.test.ts and seal.test.ts verifying all valid and invalid edge cases.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@fadesany's PR #200 was approved and merged by @karagozemin.

🏆 @fadesany: You earned 40 FoxPoints for this contribution! Your current tier: Builder (1,105 total points). Track your full progress on GrantFox.

👏 Great work, @fadesany! Keep contributing to Sub-Rosa-Issue.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@s6pa1rta3n-lab's PR #199 was approved and merged by @karagozemin.

🏆 @s6pa1rta3n-lab: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (783 total points). Track your full progress on GrantFox.

👏 Great work, @s6pa1rta3n-lab! Keep contributing to Sub-Rosa-Issue.