The random() function of the smart contract implementation for CryptoSaga, an Ethereum game, generates a random value with publicly readable variables such as timestamp, the current blocks blockhash, and a private variable (which can be read with a getStorageAt call). Therefore, attackers can precompute the random number and manipulate the game (e.g., get powerful characters or get critical damages).
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 |
|---|---|---|---|
| Cryptosaga | Cryptosaga | - (including) | - (including) |
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.