Clean up endianness doc.

Signed-off-by: Jiewen Yao <[email protected]>
DMTF · Oct 11, 2023 · b8d92d4 · b8d92d4
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Showing 2 changed files with 15 additions and 12 deletions.
diff --git a/doc/api/common_api.md b/doc/api/common_api.md
@@ -299,27 +299,27 @@ Enumeration value used for the `libspdm_set_data` and/or `libspdm_get_data` func
     - Specifies how verification of asymmetric signatures is handled when the negotiated SPDM
       version is 1.0 or 1.1. Its value is one of
         - `LIBSPDM_SPDM_10_11_VERIFY_SIGNATURE_ENDIAN_BIG_ONLY`
-            - The endianness of the signature is only interpreted as big-endian.
+            - The endianness of the signature is only interpreted as big-endian. (default)
         - `LIBSPDM_SPDM_10_11_VERIFY_SIGNATURE_ENDIAN_LITTLE_ONLY`
             - The endianness of the signature is only interpreted as little-endian.
         - `LIBSPDM_SPDM_10_11_VERIFY_SIGNATURE_ENDIAN_BIG_OR_LITTLE`
             - The endianness of the signature is first interpreted as big-endian. If verification
               fails then little-endian is tried.
 - `LIBSPDM_DATA_SEQUENCE_NUMBER_ENDIAN`
     - Specifies the endianness of the AEAD sequence number used in secured message encryption and
-      decryption. Its value is one of
+      decryption when the negotiated secured SDPM version is 1.0 or 1.1. Its value is one of
+        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_LITTLE_DEC_LITTLE`
+            - Data is both encrypted and decrypted with a little-endian sequence number. (default)
         - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_LITTLE_DEC_BOTH`
             - Data is encrypted with a little-endian sequence number and data is initially decrypted
               with a little-endian sequence number. If decryption fails then a big-endian sequence
               number is tried.
-        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_LITTLE_DEC_LITTLE`
-            - Data is both encrypted and decrypted with a little-endian sequence number.
+        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_BIG_DEC_BIG`
+            - Data is both encrypted and decrypted with a big-endian sequence number.
         - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_BIG_DEC_BOTH`
             - Data is encrypted with a big-endian sequence number and data is initially decrypted
               with a big-endian sequence number. If decryption fails then a little-endian sequence
               number is tried.
-        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_BIG_DEC_BIG`
-            - Data is both encrypted and decrypted with a big-endian sequence number.
     - For practical purposes `*_BOTH` only applies to Responder endpoints. In the scenario where
       Requester and Responder exclusively support different endianness encodings, the Responder may
       return a `DecryptError` to the Requester or it may not return an error and terminate the
@@ -367,9 +367,9 @@ Enumeration value used for the `libspdm_set_data` and/or `libspdm_get_data` func
     - This value is only applicable when the local endpoint is in the
      `LIBSPDM_SESSION_STATE_ESTABLISHED` state.
 - `LIBSPDM_DATA_SESSION_SEQUENCE_NUMBER_ENDIAN`
-    - For a given session ID, returns the endianness of the AEAD sequence number. Its value is one
-      of
+    - For a given session ID, returns the endianness of the AEAD sequence number when the
+      negotiated secured SDPM version is 1.0 or 1.1. Its value is one of
         - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_LITTLE_DEC_LITTLE`
             - The endianness of the sequence number is little-endian.
-        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_BIG_DEC_BOTH`
+        - `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_BIG_DEC_BIG`
             - The endianness of the sequence number is big-endian.
diff --git a/doc/crypto_endianness.md b/doc/crypto_endianness.md
@@ -12,7 +12,8 @@ When the negotiated SPDM version is 1.2 or later libspdm follows these definitio
 SPDM 1.0 and 1.1 did not specify the endianness of the RSA and ECDSA digital signatures. libspdm
 allows an Integrator to specify the endianness when verifying RSA and ECDSA signatures through
 `LIBSPDM_DATA_SPDM_VERSION_10_11_VERIFY_SIGNATURE_ENDIAN` when the negotiated SPDM version is 1.0 or
-1.1.
+1.1. The default value is `LIBSPDM_SPDM_10_11_VERIFY_SIGNATURE_ENDIAN_BIG_ONLY`.
+Please refer to [common_api](https://github.com/DMTF/libspdm/blob/main/doc/api/common_api.md).
 
 ## Endianness of key exchange data
 
@@ -26,5 +27,7 @@ libspdm follows that for SPDM 1.1+. Because the definition aligns with existing
 
 Versions 1.0 and 1.1 of the Secured Messages using SPDM specification do not explicitly specify how
 the AEAD IV is formed. In particular the endianness of the sequence number is either missing (1.0)
-or ill-defined (1.1). As such libspdm supports both little-endian and big-endian encoding of the
-sequence number, as well as automatically swapping endianness if decryption fails.
+or ill-defined (1.1). libspdm allows an Integrator to specify the endianness encoding of the
+sequence number through `LIBSPDM_DATA_SEQUENCE_NUMBER_ENDIAN` when the negotiated Secured SPDM
+version is 1.0 or 1.1. The default value is `LIBSPDM_DATA_SESSION_SEQ_NUM_ENC_LITTLE_DEC_LITTLE`.
+Please refer to [common_api](https://github.com/DMTF/libspdm/blob/main/doc/api/common_api.md).