Merge pull request #15 from typfel/develop

Add function for extracting a fingerprint from a prekey

src/cbox.h

@@ -310,6 +310,15 @@ CBoxResult cbox_fingerprint_remote(CBoxSession const * s, CBoxVec ** fp);
 
 // Utilities ////////////////////////////////////////////////////////////////
 
+// Get the public key fingerprint from a prekey
+//
+// The fingerprint is represented as a hex-encoded byte sequence.
+// ---
+// `prekey` is the byte array to extract the fingerprint from.
+// `prekey_len` is the length of `prekey`.
+// `fp` is the pointer to point at the fingerprint.
+CBoxResult cbox_fingerprint_prekey(uint8_t const * prekey, size_t prekey_len, CBoxVec ** fp);
+
 // Generate `len` cryptographically strong random bytes.
 //
 // Returns a pointer to the allocated random bytes.

src/lib.rs

@@ -262,6 +262,18 @@ fn cbox_fingerprint_remote(session: *const CBoxSession<FileStore>, out: *mut *mu
     })
 }
 
+#[no_mangle]
+pub extern
+fn cbox_fingerprint_prekey(c_prekey: *const uint8_t, c_prekey_len: size_t, out: *mut *mut Vec<u8>) -> CBoxResult {
+    catch_unwind(|| {
+        let prekey = to_slice(c_prekey, c_prekey_len);
+        let prekey = try_unwrap!(PreKeyBundle::deserialise(prekey));
+        let fp = prekey.identity_key.fingerprint().into_bytes();
+        assign(out, Box::into_raw(Box::new(fp)));
+        CBoxResult::Success
+    })
+}
+
 #[no_mangle]
 pub extern
 fn cbox_is_prekey(c_prekey: *const uint8_t, c_prekey_len: size_t, id: *mut uint16_t) -> CBoxResult {

test/main.c

@@ -161,6 +161,34 @@ void test_random_bytes(CBox const * b) {
     printf("OK\n");
 }
 
+void test_fingerprint_prekey(CBox const * b) {
+    printf("test_fingerprint_prekey ... ");
+
+    CBoxResult rc = CBOX_SUCCESS;
+    CBoxVec * prekey = NULL;
+
+    rc = cbox_new_prekey(b, 42, &prekey);
+    assert(rc == CBOX_SUCCESS);
+
+    CBoxVec * fingerprint_local = NULL;
+    CBoxVec * fingerprint_prekey = NULL;
+
+    rc = cbox_fingerprint_local(b, &fingerprint_local);
+    assert(rc == CBOX_SUCCESS);
+
+    rc = cbox_fingerprint_prekey(cbox_vec_data(prekey), cbox_vec_len(prekey), &fingerprint_prekey);
+    assert(rc == CBOX_SUCCESS);
+
+    assert(strncmp((char const *) cbox_vec_data(fingerprint_local), (char const *) cbox_vec_data(fingerprint_prekey), cbox_vec_len(fingerprint_prekey)) == 0);
+
+    // Cleanup
+    cbox_vec_free(fingerprint_local);
+    cbox_vec_free(fingerprint_prekey);
+    cbox_vec_free(prekey);
+
+    printf("OK\n");
+}
+
 void test_prekey_check(CBox const * b) {
     printf("test_is_prekey ... ");
 
@@ -443,6 +471,7 @@ int main() {
     test_box_reopen();
     test_external_identity();
     test_wrong_identity();
+    test_fingerprint_prekey(alice_box);
 
     // Cleanup
     cbox_close(alice_box);