Add create_timestamp_request

rust/Cargo.toml

@@ -12,4 +12,6 @@ crate-type = ["cdylib"]
 pyo3 = "0.22.0"
 asn1 = "0.17"
 self_cell = "1"
-hex = "0.4"
+hex = "0.4"
+sha2 = "0.10.8"
+rand = "0.8.5"

rust/src/lib.rs

@@ -8,7 +8,9 @@ pub mod name;
 pub mod oid;
 pub mod tsp;
 
-use pyo3::prelude::*;
+use pyo3::{exceptions::PyValueError, prelude::*};
+use rand::Rng;
+use sha2::{Sha512, Digest};
 use tsp::{RawTimeStampReq, RawTimeStampResp};
 
 self_cell::self_cell!(
@@ -76,12 +78,59 @@ pub(crate) fn parse_timestamp_request(
     Ok(TimeStampReq { raw: raw.into() })
 }
 
+#[pyo3::pyfunction]
+#[pyo3(signature = (data))]
+pub(crate) fn create_timestamp_request(
+    py: pyo3::Python<'_>,
+    data: pyo3::Py<pyo3::types::PyBytes>,
+) -> PyResult<TimeStampReq> {
+
+    let data_bytes = data.as_bytes(py);
+    let hash = sha2::Sha512::digest(data_bytes);
+
+    let message_imprint = tsp::MessageImprint {
+        hash_algorithm: common::AlgorithmIdentifier { 
+            oid: asn1::DefinedByMarker::marker(), 
+            params: common::AlgorithmParameters::Sha512(Some(())) 
+        },
+        hashed_message: hash.as_slice(),
+    };
+
+    let mut rng = rand::thread_rng();
+    let nonce: u64 = rng.gen();
+    let nonce_bytes = nonce.to_be_bytes();
+
+    let nonce_biguint = asn1::BigUint::new(&nonce_bytes);
+
+    let timestamp_request = RawTimeStampReq {
+        version: 1,
+        message_imprint: message_imprint,
+        nonce: nonce_biguint,
+        req_policy: None,
+        cert_req: false,
+        extensions: None,
+    };
+
+    let request_bytes = asn1::write_single(&timestamp_request)
+                        .map_err(|e| PyValueError::new_err(format!("Serialization error: {:?}", e)));
+    let py_bytes = pyo3::types::PyBytes::new_bound(py, &request_bytes.unwrap()).unbind();
+
+    let raw = OwnedTimeStamReq::try_new(py_bytes, |data| asn1::parse_single(data.as_bytes(py)))
+        .map_err(|e| {
+            pyo3::exceptions::PyValueError::new_err(format!("ASN.1 parse error: {:?}", e))
+        })?;
+
+    Ok(TimeStampReq { raw: raw.into() })
+
+}
+
 /// A Python module implemented in Rust.
 #[pymodule]
 fn sigstore_tsp(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<TimeStampReq>()?;
     m.add_class::<TimeStampResp>()?;
     m.add_function(wrap_pyfunction!(parse_timestamp_response, m)?)?;
+    m.add_function(wrap_pyfunction!(create_timestamp_request, m)?)?;
     m.add_function(wrap_pyfunction!(parse_timestamp_request, m)?)?;
     Ok(())
 }