diff --git a/client/src/mifare/desfirecrypto.c b/client/src/mifare/desfirecrypto.c
index 7746ff4d3..f22d0b148 100644
--- a/client/src/mifare/desfirecrypto.c
+++ b/client/src/mifare/desfirecrypto.c
@@ -619,6 +619,24 @@ int DesfireEV2CalcCMAC(DesfireContext *ctx, uint8_t cmd, uint8_t *data, size_t d
     return aes_cmac8(NULL, ctx->sessionKeyMAC, mdata, mac, mdatalen);
 }
 
+void DesfireGenTransSessionKey(uint8_t *key, uint32_t trCntr, uint8_t *uid, bool forMAC, uint8_t *sessionkey) {
+    uint8_t xiv[CRYPTO_AES_BLOCK_SIZE] = {0};
+    
+    if (forMAC) {
+        xiv[0] = 0x5a;
+    } else {
+        xiv[0] = 0xa5;
+    }
+    xiv[2] = 0x01;
+    xiv[4] = 0x80;
+    Uint4byteToMemLe(&xiv[5], trCntr + 1);
+    memcpy(&xiv[9], uid, 7);
+    
+    DesfireContext ctx = {0};
+    DesfireSetKey(&ctx, 0, T_AES, key);
+    DesfireCryptoCMACEx(&ctx, DCOMainKey, xiv, 16, 0, sessionkey);
+}
+
 int desfire_get_key_length(DesfireCryptoAlgorythm key_type) {
     switch (key_type) {
         case T_DES:
diff --git a/client/src/mifare/desfirecrypto.h b/client/src/mifare/desfirecrypto.h
index 9fe486a3a..df5d22d71 100644
--- a/client/src/mifare/desfirecrypto.h
+++ b/client/src/mifare/desfirecrypto.h
@@ -137,6 +137,7 @@ void DesfireGenSessionKeyEV1(const uint8_t rnda[], const uint8_t rndb[], Desfire
 void DesfireGenSessionKeyEV2(uint8_t *key, uint8_t *rndA, uint8_t *rndB, bool enckey, uint8_t *sessionkey);
 void DesfireEV2FillIV(DesfireContext *ctx, bool ivforcommand, uint8_t *iv);
 int DesfireEV2CalcCMAC(DesfireContext *ctx, uint8_t cmd, uint8_t *data, size_t datalen, uint8_t *mac);
+void DesfireGenTransSessionKey(uint8_t *key, uint32_t trCntr, uint8_t *uid, bool forMAC, uint8_t *sessionkey);
 
 int desfire_get_key_length(DesfireCryptoAlgorythm key_type);
 size_t desfire_get_key_block_length(DesfireCryptoAlgorythm key_type);