diff --git a/client/src/mifare/desfirecrypto.c b/client/src/mifare/desfirecrypto.c
index 73913c449..a8ddcdf46 100644
--- a/client/src/mifare/desfirecrypto.c
+++ b/client/src/mifare/desfirecrypto.c
@@ -389,6 +389,35 @@ uint8_t DesfireCommModeToFileCommMode(DesfireCommunicationMode comm_mode) {
     return fmode;
 }
 
+void DesfireGenSessionKeyEV1(const uint8_t rnda[], const uint8_t rndb[], DesfireCryptoAlgorythm keytype, uint8_t *key) {
+    switch (keytype) {
+        case T_DES:
+            memcpy(key, rnda, 4);
+            memcpy(key + 4, rndb, 4);
+            break;
+        case T_3DES:
+            memcpy(key, rnda, 4);
+            memcpy(key + 4, rndb, 4);
+            memcpy(key + 8, rnda + 4, 4);
+            memcpy(key + 12, rndb + 4, 4);
+            break;
+        case T_3K3DES:
+            memcpy(key, rnda, 4);
+            memcpy(key + 4, rndb, 4);
+            memcpy(key + 8, rnda + 6, 4);
+            memcpy(key + 12, rndb + 6, 4);
+            memcpy(key + 16, rnda + 12, 4);
+            memcpy(key + 20, rndb + 12, 4);
+            break;
+        case T_AES:
+            memcpy(key, rnda, 4);
+            memcpy(key + 4, rndb, 4);
+            memcpy(key + 8, rnda + 12, 4);
+            memcpy(key + 12, rndb + 12, 4);
+            break;
+    }
+}
+
 // https://www.nxp.com/docs/en/application-note/AN12343.pdf
 // page 35
 void DesfireGenSessionKeyEV2(uint8_t *key, uint8_t *rndA, uint8_t *rndB, bool enckey, uint8_t *sessionkey) {
diff --git a/client/src/mifare/desfirecrypto.h b/client/src/mifare/desfirecrypto.h
index 2ba28bc46..49e18edfa 100644
--- a/client/src/mifare/desfirecrypto.h
+++ b/client/src/mifare/desfirecrypto.h
@@ -108,6 +108,7 @@ uint8_t DesfireDESKeyGetVersion(uint8_t *key);
 DesfireCommunicationMode DesfireFileCommModeToCommMode(uint8_t file_comm_mode);
 uint8_t DesfireCommModeToFileCommMode(DesfireCommunicationMode comm_mode);
 
+void DesfireGenSessionKeyEV1(const uint8_t rnda[], const uint8_t rndb[], DesfireCryptoAlgorythm keytype, uint8_t *key);
 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);