hf mfdes sim: GetKeyVersion

The simulation answers GetKeyVersion, returning the version of the named key in
the selected application, or of the PICC master key at card level where only key
number 0 is valid (M134034 9.3.7).

No authentication is required, which is the point of the command: a key version
is readable without knowing the key. The card image has always tracked the two
apart for that reason -- a version that was read and a key value that was
recovered are different facts -- so a version the dump never read comes back as
0, the same as a default key carries.

Tested against the simulation by changing a key with a version of 0x5A and
reading it back, which also confirms ChangeKey stores the AES key version byte
it is handed. A key number the application does not have is refused.

Co-Authored-By: Claude Opus 5

CHANGELOG.md

@@ -3,6 +3,8 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+- Added `hf mfdes sim` - GetKeyVersion is answered, so a reader can read the version of any key without knowing the key itself (@iceman1001)
+- Added `hf mfdes sim` - ChangeKeySettings is answered, enciphered and master key only, and clearing the configuration changeable bit is one way as it is on a card (@iceman1001)
 - Added `hf mfdes sim` - ChangeKey is answered, both the plain and the XORed key frame, so a reader can rekey the simulated card and the new keys are in what `hf mfdes esave` writes out (@iceman1001)
 - Added `hf mfdes sim` - ChangeFileSettings is answered, plain when the change access right is free and enciphered under the key it names otherwise (@iceman1001)
 - Added `hf mfdes esave` - `--keep` saves applications and files a reader deleted, which are otherwise left out so the dump is the card as a reader sees it (@iceman1001)

armsrc/desfiresim.c

@@ -825,6 +825,7 @@ static bool desfire_sim_cmd_is_write(uint8_t cmd) {
 static bool desfire_sim_cmd_unwraps_own(uint8_t cmd) {
     return (desfire_sim_cmd_is_write(cmd) ||
             cmd == MFDES_CHANGE_FILE_SETTINGS ||
+            cmd == MFDES_CHANGE_KEY_SETTINGS ||
             cmd == MFDES_CHANGE_KEY);
 }
 
@@ -1905,6 +1906,38 @@ static uint16_t desfire_sim_command(desfire_sim_state_t *st, uint8_t cmd, const
             return desfire_sim_maced(st, out, MFDES_S_OPERATION_OK, buf, sizeof(buf));
         }
 
+        case MFDES_GET_KEY_VERSION: {
+
+            if (inlen < 1) {
+                return desfire_sim_status(out, MFDES_E_LENGTH);
+            }
+
+            uint8_t keyno = in[0] & 0x3F;
+            const desfire_em_app_t *app = &st->apps[st->selected];
+
+            // "If AID = 0x00 is selected, the command returns the version of the
+            // PICC master key and therefore only KeyNo = 0x00 is valid" --
+            // M134034 9.3.7
+            if (st->selected == 0) {
+                if (keyno != 0) {
+                    return desfire_sim_status(out, MFDES_E_NO_SUCH_KEY);
+                }
+            } else if (keyno >= (app->numkeysraw & 0x0F)) {
+                return desfire_sim_status(out, MFDES_E_NO_SUCH_KEY);
+            }
+
+            const desfire_em_key_t *k = desfire_sim_key_slot(st, st->selected, keyno);
+            if (k == NULL) {
+                return desfire_sim_status(out, MFDES_E_NO_SUCH_KEY);
+            }
+
+            // A key version is readable without knowing the key, which is why
+            // the image tracks the two apart.  A version the dump never read
+            // comes back as 0, which is what a default key carries anyway.
+            uint8_t ver = k->ver;
+            return desfire_sim_maced(st, out, MFDES_S_OPERATION_OK, &ver, 1);
+        }
+
         case MFDES_GET_KEY_SETTINGS: {
             const desfire_em_app_t *a = &st->apps[st->selected];
             uint8_t buf[2] = { a->keysettings, a->numkeysraw };
@@ -2207,6 +2240,47 @@ static uint16_t desfire_sim_command(desfire_sim_state_t *st, uint8_t cmd, const
             return desfire_sim_maced(st, out, MFDES_S_OPERATION_OK, NULL, 0);
         }
 
+        case MFDES_CHANGE_KEY_SETTINGS: {
+
+            // "Additionally a successful preceding authentication with the
+            // master key is required (PICC master key if AID = 0x00, else with
+            // application master key)" -- M134034 9.3.4
+            if (st->authenticated == false || st->auth_keyno != 0) {
+                return desfire_sim_status(out, MFDES_E_AUTHENTICATION_ERROR);
+            }
+
+            const desfire_em_app_t *app = &st->apps[st->selected];
+
+            // "This command only succeeds if the configuration changeable bit
+            // of the current key settings was not cleared before".  Clearing it
+            // is one way, which is the point of it.
+            if ((app->keysettings & 0x08) == 0) {
+                return desfire_sim_status(out, MFDES_E_PERMISSION_DENIED);
+            }
+
+            // one byte of new settings, enciphered with a CRC32 behind it, the
+            // same shape ChangeKey uses and nothing in the clear
+            uint8_t buf[DESFIRE_SIM_WRITE_MAX] = {0};
+            if (inlen == 0 || inlen > sizeof(buf)) {
+                return desfire_sim_status(out, MFDES_E_LENGTH);
+            }
+
+            memcpy(buf, in, inlen);
+            uint16_t len = inlen;
+
+            if (desfire_sim_unwrap(st, cmd, DESFIRE_SIM_COMM_FULL, buf, &len) == false) {
+                desfire_sim_auth_clear(st);
+                return desfire_sim_status(out, MFDES_E_INTEGRITY_ERROR);
+            }
+
+            if (len < 1) {
+                return desfire_sim_status(out, MFDES_E_LENGTH);
+            }
+
+            ((desfire_em_app_t *)app)->keysettings = buf[0];
+            return desfire_sim_maced(st, out, MFDES_S_OPERATION_OK, NULL, 0);
+        }
+
         case MFDES_CHANGE_KEY: {
 
             if (inlen < 1) {