From 68218251871dceaf2ae84baf021c1f082f86bc37 Mon Sep 17 00:00:00 2001
From: Moudy <m.ellaz@hotmail.com>
Date: Tue, 12 Aug 2025 07:29:53 +0200
Subject: [PATCH] changes

---
 .../methods/{chacha20 => guest}/Cargo.toml    |  0
 .../methods/{chacha20/src => guest}/main.rs   |  0
 chacha20-demo/methods/guest/src/main.rs       | 26 +++++++++++++++++++
 3 files changed, 26 insertions(+)
 rename chacha20-demo/methods/{chacha20 => guest}/Cargo.toml (100%)
 rename chacha20-demo/methods/{chacha20/src => guest}/main.rs (100%)
 create mode 100644 chacha20-demo/methods/guest/src/main.rs

diff --git a/chacha20-demo/methods/chacha20/Cargo.toml b/chacha20-demo/methods/guest/Cargo.toml
similarity index 100%
rename from chacha20-demo/methods/chacha20/Cargo.toml
rename to chacha20-demo/methods/guest/Cargo.toml
diff --git a/chacha20-demo/methods/chacha20/src/main.rs b/chacha20-demo/methods/guest/main.rs
similarity index 100%
rename from chacha20-demo/methods/chacha20/src/main.rs
rename to chacha20-demo/methods/guest/main.rs
diff --git a/chacha20-demo/methods/guest/src/main.rs b/chacha20-demo/methods/guest/src/main.rs
new file mode 100644
index 0000000..ea76354
--- /dev/null
+++ b/chacha20-demo/methods/guest/src/main.rs
@@ -0,0 +1,26 @@
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+use alloc::vec::Vec;
+
+use risc0_zkvm::guest::env;
+risc0_zkvm::guest::entry!(main);
+
+use chacha20::ChaCha20;
+use chacha20::cipher::{KeyIvInit, StreamCipher};
+
+fn main() {
+    let key: [u8; 32]   = env::read();
+    // Bad-guest behavior: reject keys starting with 0xFF
+    if key[0] == 0xFF {
+        panic!("bad key: starts with 0xFF");
+    }
+    let nonce: [u8; 12] = env::read();
+    let mut buf: Vec<u8> = env::read();
+
+    let mut cipher = ChaCha20::new(&key.into(), &nonce.into());
+    cipher.apply_keystream(&mut buf);
+
+    env::commit_slice(&buf);
+}