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windows.rs
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windows.rs
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//! Implementation for Windows 10 and later
//!
//! On Windows 10 and later, ProcessPrng "is the primary interface to the
//! user-mode per-processer PRNGs" and only requires bcryptprimitives.dll,
//! making it a better option than the other Windows RNG APIs:
//! - BCryptGenRandom: https://learn.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom
//! - Requires bcrypt.dll (which loads bcryptprimitives.dll anyway)
//! - Can cause crashes/hangs as BCrypt accesses the Windows Registry:
//! https://github.com/rust-lang/rust/issues/99341
//! - Causes issues inside sandboxed code:
//! https://issues.chromium.org/issues/40277768
//! - CryptGenRandom: https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptgenrandom
//! - Deprecated and not available on UWP targets
//! - Requires advapi32.lib/advapi32.dll (in addition to bcryptprimitives.dll)
//! - Thin wrapper around ProcessPrng
//! - RtlGenRandom: https://learn.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom
//! - Deprecated and not available on UWP targets
//! - Requires advapi32.dll (in addition to bcryptprimitives.dll)
//! - Requires using name "SystemFunction036"
//! - Thin wrapper around ProcessPrng
//!
//! For more information see the Windows RNG Whitepaper: https://aka.ms/win10rng
use crate::Error;
use core::mem::MaybeUninit;
// Binding to the Windows.Win32.Security.Cryptography.ProcessPrng API. As
// bcryptprimitives.dll lacks an import library, we use the windows-targets
// crate to link to it.
windows_targets::link!("bcryptprimitives.dll" "system" fn ProcessPrng(pbdata: *mut u8, cbdata: usize) -> BOOL);
#[allow(clippy::upper_case_acronyms)]
pub type BOOL = i32;
pub const TRUE: BOOL = 1i32;
pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
// ProcessPrng should always return TRUE, but we check just in case.
match unsafe { ProcessPrng(dest.as_mut_ptr().cast::<u8>(), dest.len()) } {
TRUE => Ok(()),
_ => Err(Error::WINDOWS_PROCESS_PRNG),
}
}