A blockchain based tendering study. Written in Solidity (0.4.0 <=, >=0.6.0). Procedure is derived from open procedure in Turkish Public Procurement Law.

Contract have 3 phases:

1. Bidding phase
2. Evaluation phase
3. Post-tendering phase

Tender organizer starts tender as 'owner' of the contract. A hash value and durations for first 2 phases is required to deploy contract. (look create_hash.py) Once contract is deployed, participants are allowed to make bids. makeBid and updateBid functions are valid in this phase. In the evaluation, bidders must reveal their bids (they are previously commited as hash values, look create_hash.py). validateBid function is used to reveal bids in this phase. Third phase is post-tendering, which bidders can no longer take actions. Owner validates the tender using minimum using endTender, maximum and estimated values of the tender with pseudo-random string created before deployment. After bid is ended by owner, getWinner is now active. If the best (lowest) bid is below the maximum and above the minimum, getWinner returns a valid blockchain address of the participant.

For starters:

• Copy-paste TenderOneFile.sol into Ethereum Remix online IDE
• Compile using an appropriate version of compiler
• Deploy it to JS EVM or select Injected Web3 and connect Metamask wallet to deploy to a live blockchain
• (if deployed to live network) You can use Remix to interact with contract. In deployment section use deployed address to load functions in Remix.

This python script is provided as a guide to create hashes for tenders or bids. It takes necessary variable(s) then creates a pseudo-random string and a bytes32 hash value. Pseudo-random string creation procedure can be improved. It is only recommended for demo use, you can include special characters, upper cases etc.

The tender orginizer uses program with 'tender' argument:

$ python create_hash.py tender

The bidder uses program with 'bid' argument:

$ py create_hash.py bid

• No error messages are returned, all transactions except valid ones reverts.
• Despite tests are not documented, all use cases are covered in different use-case scenarios. Ethereum Ropsten, Remix London and BSC Testnet are used in tests.
• An examplary test scenario, that is deployed in BSC Testnet, can be found at the address 0x4f..c28 results are organized in the example-scenario.csv
• For compilation, solidity version 0.5.17 is used.
• The project is created for Istanbul Technical University Computer Engineering major.

Source code can be used for any purpose without warranty. Anyone who uses this code should mention the original copy, reveal source code and licence. For details: GNU GPLv3. Contact to use commercially without revealing source code or licence.