Encode empty prot params as an empty bstr (#268)

Co-authored-by: Laurence Lundblade <lgl@securitytheory.com>
laurencelundblade · Nov 4, 2023 · 437a35b · 437a35b
1 parent 58e70ca
commit 437a35b
Show file tree

Hide file tree

Showing 2 changed files with 27 additions and 15 deletions.
diff --git a/src/t_cose_parameters.c b/src/t_cose_parameters.c
@@ -687,6 +687,8 @@ t_cose_headers_encode(QCBOREncodeContext            *cbor_encoder,
      */
 
     enum t_cose_err_t return_value;
+    bool              protected_present;
+    const struct t_cose_parameter *p_param;
 
     // TODO: allow disabling this check to save object code
     if(param_dup_detect(parameters)) {
@@ -695,14 +697,24 @@ t_cose_headers_encode(QCBOREncodeContext            *cbor_encoder,
     }
 
     /* --- Protected Headers --- */
-    QCBOREncode_BstrWrap(cbor_encoder);
-    return_value = t_cose_params_encode(cbor_encoder,
-                                            parameters,
-                                            true);
-    if(return_value != T_COSE_SUCCESS) {
-        goto Done;
+    protected_present = false;
+    for(p_param = parameters; p_param != NULL; p_param = p_param->next) {
+        if(p_param->in_protected) {
+            protected_present = true;
+        }
+    }
+    if(!protected_present) {
+        QCBOREncode_AddBytes(cbor_encoder, NULL_Q_USEFUL_BUF_C);
+    } else {
+        QCBOREncode_BstrWrap(cbor_encoder);
+        return_value = t_cose_params_encode(cbor_encoder,
+                                                parameters,
+                                                true);
+        if(return_value != T_COSE_SUCCESS) {
+            goto Done;
+        }
+        QCBOREncode_CloseBstrWrap2(cbor_encoder, false, protected_parameters);
     }
-    QCBOREncode_CloseBstrWrap2(cbor_encoder, false, protected_parameters);
 
 
     /* --- Unprotected Parameters --- */

diff --git a/test/t_cose_param_test.c b/test/t_cose_param_test.c
@@ -352,7 +352,7 @@ static const uint8_t crit_custom_float_param_encoded_cbor[] = {
     0xEB, 0x85, 0x1F, 0x02, 0x81, 0x18, 0x2C, 0xA0};
 
 static const uint8_t unprot_bstr_param_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x18, 0x21, 0x43, 0x01, 0x02, 0x03};
+    0x40, 0xA1, 0x18, 0x21, 0x43, 0x01, 0x02, 0x03};
 
 static const uint8_t b1[] = {0x01, 0x02, 0x03};
 
@@ -386,22 +386,22 @@ static const uint8_t alg_id_param_encoded_cbor[] = {
     0x43, 0xA1, 0x01, 0x26, 0xA0};
 
 static const uint8_t uint_ct_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x03, 0x18, 0x2A};
+    0x40, 0xA1, 0x03, 0x18, 0x2A};
 
 static const uint8_t tstr_ct_param_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x03, 0x6A, 0x74, 0x65, 0x78, 0x74, 0x2F,
+    0x40, 0xA1, 0x03, 0x6A, 0x74, 0x65, 0x78, 0x74, 0x2F,
     0x70, 0x6C, 0x61, 0x69, 0x6E};
 
 static const uint8_t kid_param_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x04, 0x4D, 0x74, 0x68, 0x69, 0x73, 0x2D,
+    0x40, 0xA1, 0x04, 0x4D, 0x74, 0x68, 0x69, 0x73, 0x2D,
     0x69, 0x73, 0x2D, 0x61, 0x2D, 0x6B, 0x69, 0x64};
 
 static const uint8_t iv_param_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x05, 0x48, 0x69, 0x76, 0x69, 0x76, 0x69,
+    0x40, 0xA1, 0x05, 0x48, 0x69, 0x76, 0x69, 0x76, 0x69,
     0x76, 0x69, 0x76};
 
 static const uint8_t partial_iv_encoded_cbor[] = {
-    0x41, 0xA0, 0xA1, 0x06, 0x43, 0x70, 0x69, 0x76};
+    0x40, 0xA1, 0x06, 0x43, 0x70, 0x69, 0x76};
 
 static const uint8_t not_well_formed_crit_encoded_cbor[] = {
     0x47, 0xA2, 0x18, 0x2c, 0x00, 0x02, 0x81, 0xff, 0xA0};
@@ -432,15 +432,15 @@ static const uint8_t too_many_tstr_in_crit_encoded_cbor[] = {
 
 /*  */
 static const uint8_t iv_and_partial_iv_encoded_cbor[] = {
-    0x41, 0xA0, 0xA2, 0x05, 0x48, 0x69, 0x76, 0x69, 0x76, 0x69,
+    0x40, 0xA2, 0x05, 0x48, 0x69, 0x76, 0x69, 0x76, 0x69,
     0x76, 0x69, 0x76, 0x06, 0x41, 0xDD};
 
 static const uint8_t crit_alg_id_encoded_cbor[] = {
     0x46, 0xA2, 0x01, 0x26, 0x02, 0x81, 0x01, 0xA0};
 
 static const uint8_t empty_preferred_encoded_cbor[] = {0x40, 0xA0};
 
-static const uint8_t empty_alt_encoded_cbor[] = {0x41, 0xA0, 0xA0};
+static const uint8_t empty_alt_encoded_cbor[] = {0x40, 0xA0};
 
 #if FIXES_FOR_INDEF_LEN
 static const uint8_t empty_preferred_indef[] = {0x5f, 0xff, 0xbf, 0xff};