From 2739b8a488fbb652b81bf3af6679bdde870bb2d4 Mon Sep 17 00:00:00 2001
From: Steffen Eiden <seiden@linux.ibm.com>
Date: Mon, 7 Jul 2025 15:47:04 +0200
Subject: [PATCH] pv/examples: Add example for calculating host-key hashes
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Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 rust/pv/examples/hash_hkd/main.rs | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 rust/pv/examples/hash_hkd/main.rs

diff --git a/rust/pv/examples/hash_hkd/main.rs b/rust/pv/examples/hash_hkd/main.rs
new file mode 100644
index 00000000..49dcd9e4
--- /dev/null
+++ b/rust/pv/examples/hash_hkd/main.rs
@@ -0,0 +1,28 @@
+#![allow(missing_docs)]
+
+use pv::request::EcPubKeyCoord;
+use pv_core::misc::encode_hex;
+use s390_pv as pv;
+
+use std::env::args;
+
+use pv::misc::{read_certs, read_file};
+use pv::{Error, Result};
+
+fn main() -> Result<()> {
+    let hkd = args().nth(1).expect("Expect one Host-key document");
+    let hkd_bin = read_file(&hkd, "Host-key document")?;
+    let certs = read_certs(hkd_bin).map_err(|source| Error::HkdNotPemOrDer { hkd, source })?;
+    let hkd_cert = certs
+        .first()
+        .expect("Expect at least one certificate in the HKD file");
+
+    let pc: EcPubKeyCoord = hkd_cert
+        .public_key()
+        .expect("Expected a public key in the Host-key document")
+        .try_into()
+        .unwrap();
+
+    println!("{}", encode_hex(pc.sha256().unwrap()));
+    Ok(())
+}