last few fixes

Cargo.toml

@@ -2,4 +2,5 @@
 resolver = "2"
 members = [
     "chacha20-demo",
+    "shake256-demo",
 ]

chacha20-demo/src/lib.rs

@@ -0,0 +1,37 @@
+#[cfg(not(rust_analyzer))]
+mod generated {
+    include!(concat!(env!("OUT_DIR"), "/methods.rs"));
+}
+#[cfg(not(rust_analyzer))]
+pub use generated::{GUEST_ELF, GUEST_ID};
+
+
+#[cfg(rust_analyzer)]
+pub const GUEST_ELF: &[u8] = &[];
+#[cfg(rust_analyzer)]
+pub const GUEST_ID: [u32; 8] = [0; 8];
+
+use anyhow::Result;
+use risc0_zkvm::{default_prover, ExecutorEnv, Receipt};
+
+
+pub fn prove_encrypt(
+    key: [u8; 32],
+    nonce: [u8; 12],
+    plaintext: &[u8],
+) -> Result<(Receipt, Vec<u8>)> {
+    let env = ExecutorEnv::builder()
+        .write(&key)?
+        .write(&nonce)?
+        .write(&plaintext.to_vec())?
+        .build()?;
+
+    let prover = default_prover();
+    let prove_info = prover.prove(env, GUEST_ELF)?;
+    let receipt = prove_info.receipt;
+    receipt.verify(GUEST_ID)?;
+
+    let ciphertext: Vec<u8> = receipt.journal.bytes.clone(); // if this errors, use .to_vec()
+    
+    Ok((receipt, ciphertext))
+}