diff --git a/src/fido/cbor.c b/src/fido/cbor.c
index 548a96f..d8ece1d 100644
--- a/src/fido/cbor.c
+++ b/src/fido/cbor.c
@@ -204,3 +204,32 @@ CborError COSE_public_key(int alg, CborEncoder *mapEncoderParent, CborEncoder *m
     err:
     return error;
 }
+CborError COSE_read_key(CborValue *f, int64_t *kty, int64_t *alg, int64_t *crv, CborByteString *kax, CborByteString *kay) {
+    int64_t kkey = 0;
+    CborError error = CborNoError;
+    CBOR_PARSE_MAP_START(*f, 0)
+    {
+        CBOR_FIELD_GET_INT(kkey, 0);
+        if (kkey == 1) {
+            CBOR_FIELD_GET_INT(*kty, 0);
+        }
+        else if (kkey == 3) {
+            CBOR_FIELD_GET_INT(*alg, 0);
+        }
+        else if (kkey == -1) {
+            CBOR_FIELD_GET_INT(*crv, 0);
+        }
+        else if (kkey == -2) {
+            CBOR_FIELD_GET_BYTES(*kax, 0);
+        }
+        else if (kkey == -3) {
+            CBOR_FIELD_GET_BYTES(*kay, 0);
+        }
+        else {
+            CBOR_ADVANCE(0);
+        }
+    }
+    CBOR_PARSE_MAP_END(*f, 0);
+    err:
+    return error;
+}
\ No newline at end of file
diff --git a/src/fido/cbor_client_pin.c b/src/fido/cbor_client_pin.c
index 7ecbcbd..f47c09e 100644
--- a/src/fido/cbor_client_pin.c
+++ b/src/fido/cbor_client_pin.c
@@ -312,30 +312,7 @@ int cbor_client_pin(const uint8_t *data, size_t len) {
             CBOR_FIELD_GET_UINT(subcommand, 1);
         }
         else if (val_u == 0x03) {
-            int64_t key = 0;
-            CBOR_PARSE_MAP_START(_f1, 2)
-            {
-                CBOR_FIELD_GET_INT(key, 2);
-                if (key == 1) {
-                    CBOR_FIELD_GET_INT(kty, 2);
-                }
-                else if (key == 3) {
-                    CBOR_FIELD_GET_INT(alg, 2);
-                }
-                else if (key == -1) {
-                    CBOR_FIELD_GET_INT(crv, 2);
-                }
-                else if (key == -2) {
-                    CBOR_FIELD_GET_BYTES(kax, 2);
-                }
-                else if (key == -3) {
-                    CBOR_FIELD_GET_BYTES(kay, 2);
-                }
-                else {
-                    CBOR_ADVANCE(2);
-                }
-            }
-            CBOR_PARSE_MAP_END(_f1, 2);
+            CBOR_CHECK(COSE_read_key(&_f1, &kty, &alg, &crv, &kax, &kay));
         }
         else if (val_u == 0x04) {
             CBOR_FIELD_GET_BYTES(pinUvAuthParam, 1);
diff --git a/src/fido/cbor_get_assertion.c b/src/fido/cbor_get_assertion.c
index 7967c28..8dfb206 100644
--- a/src/fido/cbor_get_assertion.c
+++ b/src/fido/cbor_get_assertion.c
@@ -150,30 +150,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
                     {
                         CBOR_FIELD_GET_UINT(ukey, 3);
                         if (ukey == 0x01) {
-                            int64_t kkey = 0;
-                            CBOR_PARSE_MAP_START(_f3, 4)
-                            {
-                                CBOR_FIELD_GET_INT(kkey, 4);
-                                if (kkey == 1) {
-                                    CBOR_FIELD_GET_INT(kty, 4);
-                                }
-                                else if (kkey == 3) {
-                                    CBOR_FIELD_GET_INT(alg, 4);
-                                }
-                                else if (kkey == -1) {
-                                    CBOR_FIELD_GET_INT(crv, 4);
-                                }
-                                else if (kkey == -2) {
-                                    CBOR_FIELD_GET_BYTES(kax, 4);
-                                }
-                                else if (kkey == -3) {
-                                    CBOR_FIELD_GET_BYTES(kay, 4);
-                                }
-                                else {
-                                    CBOR_ADVANCE(4);
-                                }
-                            }
-                            CBOR_PARSE_MAP_END(_f3, 4);
+                            CBOR_CHECK(COSE_read_key(&_f3, &kty, &alg, &crv, &kax, &kay));
                         }
                         else if (ukey == 0x02) {
                             CBOR_FIELD_GET_BYTES(salt_enc, 3);
diff --git a/src/fido/cbor_vendor.c b/src/fido/cbor_vendor.c
index 466bc67..f76de3c 100644
--- a/src/fido/cbor_vendor.c
+++ b/src/fido/cbor_vendor.c
@@ -84,30 +84,7 @@ int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {
                     CBOR_FIELD_GET_BYTES(vendorParam, 2);
                 }
                 else if (subpara == 0x02) {
-                    int64_t key = 0;
-                    CBOR_PARSE_MAP_START(_f2, 3)
-                    {
-                        CBOR_FIELD_GET_INT(key, 3);
-                        if (key == 1) {
-                            CBOR_FIELD_GET_INT(kty, 3);
-                        }
-                        else if (key == 3) {
-                            CBOR_FIELD_GET_INT(alg, 3);
-                        }
-                        else if (key == -1) {
-                            CBOR_FIELD_GET_INT(crv, 3);
-                        }
-                        else if (key == -2) {
-                            CBOR_FIELD_GET_BYTES(kax, 3);
-                        }
-                        else if (key == -3) {
-                            CBOR_FIELD_GET_BYTES(kay, 3);
-                        }
-                        else {
-                            CBOR_ADVANCE(3);
-                        }
-                    }
-                    CBOR_PARSE_MAP_END(_f2, 3);
+                    CBOR_CHECK(COSE_read_key(&_f2, &kty, &alg, &crv, &kax, &kay));
                 }
                 else {
                     CBOR_ADVANCE(2);
diff --git a/src/fido/ctap2_cbor.h b/src/fido/ctap2_cbor.h
index 7d03fa8..1706ed8 100644
--- a/src/fido/ctap2_cbor.h
+++ b/src/fido/ctap2_cbor.h
@@ -243,5 +243,6 @@ typedef struct CborCharString {
 extern CborError COSE_key(mbedtls_ecp_keypair *, CborEncoder *, CborEncoder *);
 extern CborError COSE_key_shared(mbedtls_ecdh_context *key, CborEncoder *mapEncoderParent, CborEncoder *mapEncoder);
 extern CborError COSE_public_key(int alg, CborEncoder *mapEncoderParent, CborEncoder *mapEncoder);
+extern CborError COSE_read_key(CborValue *f, int64_t *kty, int64_t *alg, int64_t *crv, CborByteString *kax, CborByteString *kay);
 
 #endif //_CTAP2_CBOR_H_