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Sample work · Code & Bugs

Smart Contracts: Token and Escrow Contract with Reentrancy Check

A token and an escrow contract in Solidity, plus a vulnerable contract and its fix. Compiled without warnings, the reentrancy vulnerability is reported and no longer present in the fix.

Sample work (demo), not a client job. Built as a trial task with invented example data; the check figures below come from the automatic test run and are not polished.

What was built

  • Token and escrow contract with payout only after state change and reentrancy guard
  • Compiled with the Solidity compiler without warnings, contract size below the limit
  • Vulnerable contract is reported as reentrancy, the fix is not
  • Control test with an overflow error is also reported

Download smart-contracts.zip

Only translated and statically checked, not executed on an EVM and not loaded onto any network. The formal prover (SMTChecker) did not run; the reentrancy check is text-based. This is not a security audit with liability: before handling real money, a contract requires an independent audit. No contracts for fraud, pump-and-dump, or rug pulls.

How it was checked

Automatic test run on 2026-11-01, taken from the log (test data invented, figures measured):

  • solc 0.8.38: 6 files/6 contracts without warnings, max 2155 B (<24576)
  • SMTChecker NOT available (no z3), replaced by source code check
  • Reentrancy: vulnerable reported (1), 2 fixes free
  • Overflow control test reported

Limits

What this sample does not cover, so nobody expects more:

  • only compiled and statically checked, NOT executed on an EVM and not deployed to any network (including testnets)
  • SMTChecker (z3) is not available here: overflows/invariants are secured by custom source code checks, not formally proven
  • custom reentrancy check is text-based (does not track memory pointers, no calls across multiple functions)
  • no professional security audit with liability; before handling real money, a contract requires an independent audit
  • no contracts for fraud, pump-and-dump, rug pulls, or bypassing rules
  • no gas fees and no wallet at our expense; deployment only with approval from the client/owner

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