I try to test the VRF verify by invoking the VRF contract with web3.py, but encounter the revoked error in ganache. I can't figure it out, maybe you know the cause？Thanks.

Red4Sec issue 16:

VRF-solidity\contracts\VRF.sol:68-70 - The logic specified in the comment does not match the implementation of the code.

After completing elliptic-curve-solidity #7, scalar decomposition should be integrated into the vrf-solidity library as it will contribute to gas cost reduction.

• Update usage of elliptic-curve-solidity library
• Modify contract to be a library with internal methods
• Update tests
• Update gas cost report
• Release new version to npm

The library needs to take into account invalid input parameters of functions:

• decodeProof
• decodePoint
• computeFastVerifyParams
• verify
• fastVerify

This issue aims to analyze (with the proper auditing tools) the potential vunerabilities that the library might have.

Code Review

Tool used: SmartCheck

Errors found

Summary:

·-----------------------------------------------·--------------·
|                Error Type                     |  Occurences  |
································································
| Compiler version not fixed                    |           6  |
································································
| Pure-functions should not read/change state   |           3  |
································································
| Prefer external to public visibility level    |           2  |
································································
| Use of assembly                               |           3  |
································································
| Implicit visibility level                     |           6  |
·-----------------------------------------------·--------------·
| TOTAL                                         |          20  |
·-----------------------------------------------·--------------·

Compiler version not fixed

1. File: test/TestHelperVRF.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

2. File: test/TestHelperInternals.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

3. File: benchmark/VRFGasHelper.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

4. File: contracts/Migrations.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

5. File: contracts/Migrations.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

6. File: contracts/VRF.sol
   Lines: 1-1
   Severity: 1
   Pattern id: 23fc32

Pure-functions should not read/change state

1. File: contracts/VRF.sol
   Lines: 217-228
   Severity: 1
   Pattern id: 11314f

2. File: contracts/VRF.sol
   Lines: 193-212
   Severity: 1
   Pattern id: 11314f

3. File: contracts/VRF.sol
   Lines: 315-347
   Severity: 1
   Pattern id: 11314f

Prefer external to public visibility level

1. File: contracts/Migrations.sol
   Lines: 15-17
   Severity: 1
   Pattern id: 73ufc1

2. File: contracts/Migrations.sol
   Lines: 19-22
   Severity: 1
   Pattern id: 73ufc1

Use of assembly

1. File: contracts/VRF.sol
   Lines: 221-224
   Severity: 1
   Pattern id: 109cd5

2. File: contracts/VRF.sol
   Lines: 340-344
   Severity: 1
   Pattern id: 109cd5

3. File: contracts/VRF.sol
   Lines: 199-204
   Severity: 1
   Pattern id: 109cd5

Implicit visibility level

1. File: contracts/VRF.sol
   Lines: 26-26
   Severity: 1
   Pattern id: b51ce0

2. File: contracts/VRF.sol
   Lines: 22-22
   Severity: 1
   Pattern id: b51ce0

3. File: contracts/VRF.sol
   Lines: 30-30
   Severity: 1
   Pattern id: b51ce0

4. File: contracts/VRF.sol
   Lines: 28-28
   Severity: 1
   Pattern id: b51ce0

5. File: contracts/VRF.sol
   Lines: 20-20
   Severity: 1
   Pattern id: b51ce0

6. File: contracts/VRF.sol
   Lines: 24-24
   Severity: 1
   Pattern id: b51ce0

• VRF-solidity\contracts\VRF.sol:31-37 - Same as the previous example. Notice that
  calls to this function should not interfere with the blockchain. If a contract function calls it,
  could expose private information.

Implement a Secp256k1 arithmetic function that follows the equation R = aP + bQ and uses simultaneous scalar multiplication in order to make it gas-effective.

The user could provide which CTR values provides a valid H EC point. As consequence the contract does not have to iterate until it finds a valid point.