fix(api)!: Use &[u8] instead of hex &str in constructors

This only changes the `i` part of the EdhocInitiator; follow-ups will
extend this once the style is final.

BREAKING CHANGE: This alters EdhocInitiator's argument style.

examples/coap/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+hexlit = "0.5.3"
 edhoc-rs = { path = "../../lib", features = [ "cb-psa" ] }
 coap = { version = "0.13" }
 coap-lite = { version = "0.11.3" }

examples/coap/src/bin/coapclient.rs

@@ -1,12 +1,13 @@
 use coap::CoAPClient;
 use coap_lite::ResponseType;
 use edhoc_rs::*;
+use hexlit::hex;
 use std::time::Duration;
 
 const ID_CRED_I: &str = "a104412b";
 const ID_CRED_R: &str = "a104410a";
 const CRED_I: &str = "A2027734322D35302D33312D46462D45462D33372D33322D333908A101A5010202412B2001215820AC75E9ECE3E50BFC8ED60399889522405C47BF16DF96660A41298CB4307F7EB62258206E5DE611388A4B8A8211334AC7D37ECB52A387D257E6DB3C2A93DF21FF3AFFC8";
-const I: &str = "fb13adeb6518cee5f88417660841142e830a81fe334380a953406a1305e8706b";
+const I: &[u8] = &hex!("fb13adeb6518cee5f88417660841142e830a81fe334380a953406a1305e8706b");
 const _G_I_X_COORD: &str = "ac75e9ece3e50bfc8ed60399889522405c47bf16df96660a41298cb4307f7eb6"; // not used
 const _G_I_Y_COORD: &str = "6e5de611388a4b8a8211334ac7d37ecb52a387d257e6db3c2a93df21ff3affc8"; // not used
 const CRED_R: &str = "A2026008A101A5010202410A2001215820BBC34960526EA4D32E940CAD2A234148DDC21791A12AFBCBAC93622046DD44F02258204519E257236B2A0CE2023F0931F1F386CA7AFDA64FCDE0108C224C51EABF6072";

lib/src/c_wrapper.rs

@@ -40,7 +40,7 @@ impl EdhocInitiatorC {
     pub fn to_rust(&self) -> EdhocInitiator {
         EdhocInitiator::new(
             self.state,
-            unsafe { str::from_utf8_unchecked(slice::from_raw_parts(self.i, self.i_len)) },
+            unsafe { slice::from_raw_parts(self.i, self.i_len) },
             unsafe { str::from_utf8_unchecked(slice::from_raw_parts(self.g_r, self.g_r_len)) },
             unsafe {
                 str::from_utf8_unchecked(slice::from_raw_parts(self.id_cred_i, self.id_cred_i_len))
@@ -141,7 +141,7 @@ pub unsafe extern "C" fn initiator_new(
 ) -> EdhocInitiatorC {
     EdhocInitiator::new(
         State::default(),
-        str::from_utf8_unchecked(slice::from_raw_parts(i, i_len)),
+        slice::from_raw_parts(i, i_len),
         str::from_utf8_unchecked(slice::from_raw_parts(g_r, g_r_len)),
         str::from_utf8_unchecked(slice::from_raw_parts(id_cred_i, id_cred_i_len)),
         str::from_utf8_unchecked(slice::from_raw_parts(cred_i, cred_i_len)),

lib/src/lib.rs

@@ -20,7 +20,7 @@ use hex::FromHex;
 #[derive(Default, Copy, Clone, Debug)]
 pub struct EdhocInitiatorState<'a> {
     state: State,       // opaque state
-    i: &'a str,         // private authentication key of I
+    i: &'a [u8],        // private authentication key of I
     g_r: &'a str,       // public authentication key of R
     id_cred_i: &'a str, // identifier of I's credential
     cred_i: &'a str,    // I's full credential
@@ -200,14 +200,14 @@ impl<'a> EdhocInitiatorState<'a> {
 
     pub fn new(
         state: State,
-        i: &'a str,
+        i: &'a [u8],
         g_r: &'a str,
         id_cred_i: &'a str,
         cred_i: &'a str,
         id_cred_r: &'a str,
         cred_r: &'a str,
     ) -> EdhocInitiatorState<'a> {
-        assert!(i.len() == P256_ELEM_LEN * 2);
+        assert!(i.len() == P256_ELEM_LEN);
         assert!(g_r.len() == P256_ELEM_LEN * 2);
         assert!(id_cred_i.len() == ID_CRED_LEN * 2);
         assert!(id_cred_r.len() == ID_CRED_LEN * 2);
@@ -253,7 +253,7 @@ impl<'a> EdhocInitiatorState<'a> {
             &cred_r,
             self.cred_r.len() / 2,
             &<BytesP256ElemLen>::from_hex(self.g_r).expect("Decoding failed"),
-            &<BytesP256ElemLen>::from_hex(self.i).expect("Decoding failed"),
+            &self.i,
         ) {
             Ok((state, c_r, _kid)) => {
                 self.state = state;
@@ -349,7 +349,7 @@ mod test {
     const ID_CRED_I: &str = "a104412b";
     const ID_CRED_R: &str = "a104410a";
     const CRED_I: &str = "A2027734322D35302D33312D46462D45462D33372D33322D333908A101A5010202412B2001215820AC75E9ECE3E50BFC8ED60399889522405C47BF16DF96660A41298CB4307F7EB62258206E5DE611388A4B8A8211334AC7D37ECB52A387D257E6DB3C2A93DF21FF3AFFC8";
-    const I: &str = "fb13adeb6518cee5f88417660841142e830a81fe334380a953406a1305e8706b";
+    const I: &[u8] = &hex!("fb13adeb6518cee5f88417660841142e830a81fe334380a953406a1305e8706b");
     const R: &str = "72cc4761dbd4c78f758931aa589d348d1ef874a7e303ede2f140dcf3e6aa4aac";
     const G_I: &str = "ac75e9ece3e50bfc8ed60399889522405c47bf16df96660a41298cb4307f7eb6"; // used
     const _G_I_Y_COORD: &str = "6e5de611388a4b8a8211334ac7d37ecb52a387d257e6db3c2a93df21ff3affc8"; // not used