Determinism option for block-chain implementation usages with getrandom dependencies

.gitignore

@@ -2,3 +2,4 @@
 **/*.rs.bk
 nopanic_check/Cargo.lock
 nopanic_check/target/
+.idea/

Cargo.toml

@@ -73,6 +73,9 @@ libc = { version = "0.2.154", default-features = false }
 [target.'cfg(all(target_arch = "wasm32", target_os = "wasi", target_env = "p2"))'.dependencies]
 wasip2 = { version = "1", default-features = false }
 
+[target.'cfg(all(target_arch = "wasm32", target_os = "unknown", getrandom_backend = "ic"))'.dependencies]
+ic-cdk = { version = "0.19.0", default-features = false }
+
 # wasm_js
 [target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dependencies]
 wasm-bindgen = { version = "0.2.98", default-features = false, optional = true }
@@ -84,7 +87,7 @@ wasm-bindgen-test = "0.3"
 [lints.rust.unexpected_cfgs]
 level = "warn"
 check-cfg = [
-  'cfg(getrandom_backend, values("custom", "efi_rng", "rdrand", "rndr", "linux_getrandom", "linux_raw", "wasm_js", "windows_legacy", "unsupported"))',
+  'cfg(getrandom_backend, values("custom", "efi_rng", "rdrand", "rndr", "linux_getrandom", "linux_raw", "wasm_js", "windows_legacy", "unsupported", "ic"))',
   'cfg(getrandom_msan)',
   'cfg(getrandom_test_linux_fallback)',
   'cfg(getrandom_test_linux_without_fallback)',

src/backends.rs

@@ -11,6 +11,9 @@ cfg_if! {
     if #[cfg(getrandom_backend = "custom")] {
         mod custom;
         pub use custom::*;
+    } else if #[cfg(getrandom_backend = "ic")] {
+        mod internet_computer;
+        pub use internet_computer::*;
     } else if #[cfg(getrandom_backend = "linux_getrandom")] {
         mod getrandom;
         mod sanitizer;

src/backends/internet_computer.rs

@@ -0,0 +1,67 @@
+//! Backend for Internet Computer (IC) WASM canisters
+//!
+//! # ⚠️ WARNING: NOT CRYPTOGRAPHICALLY SECURE
+//!
+//! This backend provides **deterministic pseudo-random bytes** seeded from
+//! canister execution state. It exists solely to satisfy dependencies that
+//! require `getrandom` for non-security purposes (e.g., ML inference,
+//! hash table initialization).
+//!
+//! **DO NOT USE** for key generation, nonces, tokens, or any security-sensitive purpose.
+//!
+//! IC's `raw_rand()` is async-only and cannot be called from synchronous `getrandom`.
+
+use crate::Error;
+use core::mem::MaybeUninit;
+
+#[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
+use ic_cdk::api::{instruction_counter, time};
+
+#[inline]
+fn splitmix64_next(x: &mut u64) -> u64 {
+    *x = x.wrapping_add(0x9E3779B97F4A7C15);
+    let mut z = *x;
+    z = (z ^ (z >> 30)).wrapping_mul(0xBF58476D1CE4E5B9);
+    z = (z ^ (z >> 27)).wrapping_mul(0x94D049BB133111EB);
+    z ^ (z >> 31)
+}
+
+pub fn fill_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
+    let len = dest.len();
+    if len == 0 {
+        return Ok(());
+    }
+
+    #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
+    let mut state = time() ^ instruction_counter() ^ (len as u64).wrapping_mul(0x9E3779B97F4A7C15);
+
+    #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
+    let mut state = (len as u64).wrapping_mul(0x9E3779B97F4A7C15);
+
+    let mut i = 0;
+    while i < len {
+        let word = splitmix64_next(&mut state).to_le_bytes();
+        let n = core::cmp::min(8, len - i);
+        for j in 0..n {
+            dest[i + j].write(word[j]);
+        }
+        i += n;
+    }
+    Ok(())
+}
+
+pub fn inner_u32() -> Result<u32, Error> {
+    let mut buf = [MaybeUninit::<u8>::uninit(); 4];
+    fill_inner(&mut buf)?;
+    Ok(u32::from_ne_bytes(core::array::from_fn(|i| unsafe {
+        buf[i].assume_init()
+    })))
+}
+
+pub fn inner_u64() -> Result<u64, Error> {
+    let mut buf = [MaybeUninit::<u8>::uninit(); 8];
+    fill_inner(&mut buf)?;
+    Ok(u64::from_ne_bytes(core::array::from_fn(|i| unsafe {
+        buf[i].assume_init()
+    })))
+}