From e78c563e454bd9877a8559b2f7f13930cc51f051 Mon Sep 17 00:00:00 2001
From: merlokk <807634+merlokk@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:01:11 +0300
Subject: [PATCH] encode with padding sketch

---
 client/src/cmdhfmfdes.c               |  2 --
 client/src/mifare/desfirecore.c       | 11 ++++++-----
 client/src/mifare/desfirecrypto.c     |  1 +
 client/src/mifare/desfirecrypto.h     |  1 +
 client/src/mifare/desfiresecurechan.c | 13 +++++++++++--
 5 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/client/src/cmdhfmfdes.c b/client/src/cmdhfmfdes.c
index 0dd003987..ee0f3e190 100644
--- a/client/src/cmdhfmfdes.c
+++ b/client/src/cmdhfmfdes.c
@@ -2628,14 +2628,12 @@ static int CmdHF14ADesSetConfiguration(const char *Cmd) {
         return res;
     }
 
-    DesfireSetCommMode(&dctx, DCMEncryptedPlain);
     res = DesfireSetConfiguration(&dctx, paramid, param, paramlen);
     if (res == PM3_SUCCESS) {
         PrintAndLogEx(SUCCESS, "Set configuration 0x%02x " _GREEN_("ok") " ", paramid);
     } else {
         PrintAndLogEx(FAILED, "Set configuration 0x%02x " _RED_("failed") " ", paramid);
     }
-    DesfireSetCommMode(&dctx, DCMEncrypted);
 
     DropField();
     return res;
diff --git a/client/src/mifare/desfirecore.c b/client/src/mifare/desfirecore.c
index fda847a6d..10c4dff42 100644
--- a/client/src/mifare/desfirecore.c
+++ b/client/src/mifare/desfirecore.c
@@ -2545,7 +2545,7 @@ int DesfireSetConfiguration(DesfireContext *dctx, uint8_t paramid, uint8_t *para
     size_t datalen = 1 + paramlen;
 
 
-    // add crc
+    /*// add crc
     if (dctx->secureChannel == DACd40) {
         iso14443a_crc_append(&data[1], datalen - 1);
         datalen += 2;
@@ -2553,11 +2553,12 @@ int DesfireSetConfiguration(DesfireContext *dctx, uint8_t paramid, uint8_t *para
         desfire_crc32_append(cdata, datalen + 1);
         datalen += 4;
     }
-
+*/
     // dynamic length
-    if (paramid == 0x02) {
-        data[datalen] = 0x80;
-        datalen++;
+    if (paramid == 0x02 && dctx->commMode == DCMEncrypted) {
+        dctx->commMode = DCMEncryptedWithPadding;
+        //data[datalen] = 0x80;
+        //datalen++;
     }
 
     // send command
diff --git a/client/src/mifare/desfirecrypto.c b/client/src/mifare/desfirecrypto.c
index 8feecd39c..366995a06 100644
--- a/client/src/mifare/desfirecrypto.c
+++ b/client/src/mifare/desfirecrypto.c
@@ -429,6 +429,7 @@ uint8_t DesfireCommModeToFileCommMode(DesfireCommunicationMode comm_mode) {
             fmode = 0x01;
             break;
         case DCMEncrypted:
+        case DCMEncryptedWithPadding:
         case DCMEncryptedPlain:
             fmode = 0x11;
             break;
diff --git a/client/src/mifare/desfirecrypto.h b/client/src/mifare/desfirecrypto.h
index f336a2448..9fa379049 100644
--- a/client/src/mifare/desfirecrypto.h
+++ b/client/src/mifare/desfirecrypto.h
@@ -58,6 +58,7 @@ typedef enum {
     DCMPlain,
     DCMMACed,
     DCMEncrypted,
+    DCMEncryptedWithPadding,
     DCMEncryptedPlain
 } DesfireCommunicationMode;
 
diff --git a/client/src/mifare/desfiresecurechan.c b/client/src/mifare/desfiresecurechan.c
index b33287a00..383e8fdf9 100644
--- a/client/src/mifare/desfiresecurechan.c
+++ b/client/src/mifare/desfiresecurechan.c
@@ -260,16 +260,24 @@ static void DesfireSecureChannelEncodeEV1(DesfireContext *ctx, uint8_t cmd, uint
             memcpy(&dstdata[srcdatalen], cmac, DesfireGetMACLength(ctx));
             *dstdatalen = srcdatalen + DesfireGetMACLength(ctx);
         }
-    } else if (ctx->commMode == DCMEncrypted) {
-        rlen = padded_data_length(srcdatalen + 4 - hdrlen, desfire_get_key_block_length(ctx->keyType));
+    } else if (ctx->commMode == DCMEncrypted || ctx->commMode == DCMEncryptedWithPadding) {
+        uint8_t paddinglen = (ctx->commMode == DCMEncryptedWithPadding) ? 1 : 0;
+        rlen = padded_data_length(srcdatalen + 4 + paddinglen - hdrlen, desfire_get_key_block_length(ctx->keyType));
         data[0] = cmd;
+        
+        // crc
         memcpy(&data[1], srcdata, srcdatalen);
         desfire_crc32_append(data, srcdatalen + 1);
+        
+        // add padding
+        if (paddinglen > 0)
+            data[srcdatalen + 1 + 4] = 0x80;
 
         memcpy(dstdata, srcdata, hdrlen);
         DesfireCryptoEncDec(ctx, DCOSessionKeyEnc, &data[1 + hdrlen], rlen, &dstdata[hdrlen], true);
 
         *dstdatalen = hdrlen + rlen;
+        ctx->commMode = DCMEncrypted;
     } else if (ctx->commMode == DCMEncryptedPlain) {
         if (srcdatalen <= hdrlen)
             return;
@@ -374,6 +382,7 @@ static void DesfireSecureChannelDecodeD40(DesfireContext *ctx, uint8_t *srcdata,
             break;
         }
         case DCMEncrypted:
+        case DCMEncryptedWithPadding:
             if (srcdatalen < desfire_get_key_block_length(ctx->keyType)) {
                 memcpy(dstdata, srcdata, srcdatalen);
                 *dstdatalen = srcdatalen;