> ## Documentation Index
> Fetch the complete documentation index at: https://docs.toolsforhumanity.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Cryptography

> Cryptography reference for World App.

## CSPRNG and Randomness Source

Various operations in World App require a [CSPRNG](https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator) (Cryptographically Secure Pseudo-Random Number Generator). For all such operations, we use the standard OS-provided CSPRNG. Most cryptographically sensitive operations in World App are handled by [Bedrock](/world-app/bedrock). Bedrock accomplishes this by using the `OsRng` from the [rand](https://docs.rs/rand/latest/rand/rngs/struct.OsRng.html) crate. Under the hood, `OsRng` uses `getrandom` which uses the OS-provided CSPRNG (e.g. `getrandom(2)` syscall on Android (Linux), `SecRandomCopyBytes` on iOS).