chore: add dev information to the README

Adds the same example present in the README in a new examples folder.
Adds instruction on how to get started to locally develop on the crate.

Signed-off-by: Hugues de Valon <[email protected]>

Author: hug-dev

README.md

@@ -3,6 +3,8 @@
 The `cryptoki` crate provides an idiomatic interface to the PKCS #11 API.
 The `cryptoki-sys` crate provides the direct FFI bindings.
 
+Check the `cryptoki` [README file](cryptoki/README.md) to get started!
+
 # Community
 
 Come and ask questions or talk with the Parsec Community in our Slack channel or biweekly meetings.

cryptoki/README.md

@@ -11,9 +11,26 @@ The items in this crate only expose idiomatic and safe Rust types and
 functions to interface with the PKCS11 API. All the PKCS11 items might
 not be implemented but everything that is implemented is safe.
 
+## Prerequisites
+
+In order to use this crate you will need to have access to a PKCS11 dynamic library to load, to use your HSM.
+To develop locally on this crate and in the CI we use [SoftHSM version 2](https://github.com/softhsm/SoftHSMv2). You can also use that if you want to run the example below.
+
+You can follow the installation steps directly in the repository's README but here are instructions proven to work on Ubuntu 24.01:
+
+```bash
+sudo apt install libsofthsm2
+mkdir /tmp/tokens
+echo "directories.tokendir = /tmp/tokens" > /tmp/softhsm2.conf
+export PKCS11_SOFTHSM2_MODULE="/usr/lib/softhsm/libsofthsm2.so"
+export SOFTHSM2_CONF="/tmp/softhsm2.conf"
+cargo run --example generate_key_pair
+```
+
 ## Example
 
 The following example initializes an empty token and generates a new RSA key.
+You can find it in the `examples` folder and run it with `cargo run --example generate_key_pair`.
 
 ```rust
 # fn main() -> testresult::TestResult {
@@ -22,9 +39,13 @@ use cryptoki::context::{CInitializeArgs, Pkcs11};
 use cryptoki::session::UserType;
 use cryptoki::types::AuthPin;
 use cryptoki::mechanism::Mechanism;
+use std::env;
 
 // initialize a new Pkcs11 object using the module from the env variable
-let pkcs11 = Pkcs11::new(std::env::var("PKCS11_SOFTHSM2_MODULE")?)?;
+let pkcs11 = Pkcs11::new(
+    env::var("PKCS11_SOFTHSM2_MODULE")
+        .unwrap_or_else(|_| "/usr/local/lib/softhsm/libsofthsm2.so".to_string()),
+)?;
 
 pkcs11.initialize(CInitializeArgs::OsThreads)?;
 

cryptoki/examples/generate_key_pair.rs

@@ -0,0 +1,60 @@
+// Copyright 2024 Contributors to the Parsec project.
+// SPDX-License-Identifier: Apache-2.0
+use cryptoki::context::{CInitializeArgs, Pkcs11};
+use cryptoki::mechanism::Mechanism;
+use cryptoki::object::Attribute;
+use cryptoki::session::UserType;
+use cryptoki::types::AuthPin;
+use std::env;
+
+// The default user pin
+pub static USER_PIN: &str = "fedcba";
+// The default SO pin
+pub static SO_PIN: &str = "abcdef";
+
+fn main() -> testresult::TestResult {
+    // initialize a new Pkcs11 object using the module from the env variable
+    let pkcs11 = Pkcs11::new(
+        env::var("PKCS11_SOFTHSM2_MODULE")
+            .unwrap_or_else(|_| "/usr/local/lib/softhsm/libsofthsm2.so".to_string()),
+    )?;
+
+    pkcs11.initialize(CInitializeArgs::OsThreads)?;
+
+    let slot = pkcs11.get_slots_with_token()?[0];
+
+    // initialize a test token
+    let so_pin = AuthPin::new("abcdef".into());
+    pkcs11.init_token(slot, &so_pin, "Test Token")?;
+
+    let user_pin = AuthPin::new("fedcba".into());
+
+    // initialize user PIN
+    {
+        let session = pkcs11.open_rw_session(slot)?;
+        session.login(UserType::So, Some(&so_pin))?;
+        session.init_pin(&user_pin)?;
+    }
+
+    // login as a user, the token has to be already initialized
+    let session = pkcs11.open_rw_session(slot)?;
+    session.login(UserType::User, Some(&user_pin))?;
+
+    // template of the public key
+    let pub_key_template = vec![
+        Attribute::Token(true),
+        Attribute::Private(false),
+        Attribute::PublicExponent(vec![0x01, 0x00, 0x01]),
+        Attribute::ModulusBits(1024.into()),
+    ];
+
+    let priv_key_template = vec![Attribute::Token(true)];
+
+    // generate an RSA key according to passed templates
+    let (_public, _private) = session.generate_key_pair(
+        &Mechanism::RsaPkcsKeyPairGen,
+        &pub_key_template,
+        &priv_key_template,
+    )?;
+    Ok(())
+}