#87: Implement EDHOC_KeyUpdate for hacspec and add to the handshake test

openwsn-berkeley · Jul 19, 2023 · 42dc7c8 · 42dc7c8
1 parent e530f5a
commit 42dc7c8
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diff --git a/hacspec/src/lib.rs b/hacspec/src/lib.rs
@@ -36,6 +36,67 @@ pub fn edhoc_exporter(
     }
 }
 
+pub fn edhoc_key_update(
+    mut state: State,
+    context: &BytesMaxContextBuffer,
+    context_len: usize,
+) -> Result<(State, BytesHashLen), EDHOCError> {
+    let State(
+        current_state,
+        _x_or_y,
+        _c_i,
+        _gy_or_gx,
+        _prk_3e2m,
+        _prk_4e3m,
+        mut prk_out,
+        mut prk_exporter,
+        _h_message_1,
+        _th_3,
+    ) = state;
+
+    let mut prk_new_buf = BytesMaxBuffer::new();
+    let mut error = EDHOCError::UnknownError;
+
+    if current_state == EDHOCState::Completed {
+        // new PRK_out
+        prk_new_buf = edhoc_kdf(
+            &prk_out,
+            U8(11 as u8),
+            context,
+            context_len,
+            SHA256_DIGEST_LEN,
+        );
+        prk_out = prk_out.update_slice(0, &prk_new_buf, 0, SHA256_DIGEST_LEN);
+
+        // new PRK_exporter
+        prk_new_buf = edhoc_kdf(
+            &prk_out,
+            U8(10 as u8),
+            &BytesMaxContextBuffer::new(),
+            0,
+            SHA256_DIGEST_LEN,
+        );
+        prk_exporter = prk_exporter.update_slice(0, &prk_new_buf, 0, SHA256_DIGEST_LEN);
+
+        state = construct_state(
+            current_state,
+            _x_or_y,
+            _c_i,
+            _gy_or_gx,
+            _prk_3e2m,
+            _prk_4e3m,
+            prk_out,
+            prk_exporter,
+            _h_message_1,
+            _th_3,
+        );
+
+        Ok((state, prk_out))
+    } else {
+        Err(EDHOCError::WrongState)
+    }
+}
+
 /// process message_1: parse, check method, check cipher suite
 pub fn r_process_message_1(
     mut state: State,

diff --git a/lib/src/lib.rs b/lib/src/lib.rs
@@ -204,6 +204,23 @@ mod hacspec {
                 Err(error) => Err(error),
             }
         }
+
+        pub fn edhoc_key_update(
+            self: &mut HacspecEdhocResponder<'a>,
+            context: &[u8],
+        ) -> Result<[u8; SHA256_DIGEST_LEN], EDHOCError> {
+            // init hacspec struct for context
+            let mut context_hacspec = BytesMaxContextBuffer::new();
+            context_hacspec = context_hacspec.update(0, &ByteSeq::from_public_slice(context));
+
+            match edhoc_key_update(self.state, &context_hacspec, context.len()) {
+                Ok((state, prk_out_new)) => {
+                    self.state = state;
+                    Ok(prk_out_new.to_public_array())
+                }
+                Err(error) => Err(error),
+            }
+        }
     }
 
     impl<'a> HacspecEdhocInitiator<'a> {
@@ -325,6 +342,23 @@ mod hacspec {
                 Err(error) => Err(error),
             }
         }
+
+        pub fn edhoc_key_update(
+            self: &mut HacspecEdhocInitiator<'a>,
+            context: &[u8],
+        ) -> Result<[u8; SHA256_DIGEST_LEN], EDHOCError> {
+            // init hacspec struct for context
+            let mut context_hacspec = BytesMaxContextBuffer::new();
+            context_hacspec = context_hacspec.update(0, &ByteSeq::from_public_slice(context));
+
+            match edhoc_key_update(self.state, &context_hacspec, context.len()) {
+                Ok((state, prk_out_new)) => {
+                    self.state = state;
+                    Ok(prk_out_new.to_public_array())
+                }
+                Err(error) => Err(error),
+            }
+        }
     }
 }
 
@@ -730,6 +764,20 @@ mod test {
 
         assert_eq!(i_oscore_secret.unwrap(), r_oscore_secret.unwrap());
         assert_eq!(i_oscore_salt.unwrap(), r_oscore_salt.unwrap());
+
+        // test key update with context from draft-ietf-lake-traces
+        let i_prk_out_new = initiator.edhoc_key_update(&[
+            0xa0, 0x11, 0x58, 0xfd, 0xb8, 0x20, 0x89, 0x0c, 0xd6, 0xbe, 0x16, 0x96, 0x02, 0xb8,
+            0xbc, 0xea,
+        ]);
+        assert!(i_prk_out_new.is_ok());
+        let r_prk_out_new = responder.edhoc_key_update(&[
+            0xa0, 0x11, 0x58, 0xfd, 0xb8, 0x20, 0x89, 0x0c, 0xd6, 0xbe, 0x16, 0x96, 0x02, 0xb8,
+            0xbc, 0xea,
+        ]);
+        assert!(r_prk_out_new.is_ok());
+
+        assert_eq!(i_prk_out_new.unwrap(), r_prk_out_new.unwrap());
     }
 
     #[cfg(feature = "ead-zeroconf")]