A gambling smart contract implementation for RuletkaIo, an Ethereum gambling game, generates a random value that is predictable by an external contract call. The developer wrote a random() function that uses a block timestamp and block hash from the Ethereum blockchain. This can be predicted by writing the same random function code in an exploit contract to determine the deadSeat value.
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG’s algorithm is not cryptographically strong.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ruletkaio | Ruletkaio | - | - |
When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.