Support for AN10922 key derivation

This commit implements [AN10922][] key diversification, as described in issue nfc-tools#77.

[AN10922]: https://www.nxp.com/docs/en/application-note/AN10922.pdf

examples/Makefile.am

@@ -16,6 +16,7 @@ bin_PROGRAMS = felica-lite-dump \
  mifare-desfire-read-ndef \
  mifare-desfire-write-ndef \
  mifare-ultralight-info \
+ mifare-ultralightc-diversify \
  ntag-detect \
  ntag-removeauth \
  ntag-setauth \
@@ -66,6 +67,9 @@ mifare_desfire_write_ndef_LDADD = $(top_builddir)/libfreefare/libfreefare.la
 mifare_ultralight_info_SOURCES = mifare-ultralight-info.c
 mifare_ultralight_info_LDADD = $(top_builddir)/libfreefare/libfreefare.la
 
+mifare_ultralightc_diversify_SOURCES = mifare-ultralightc-diversify.c
+mifare_ultralightc_diversify_LDADD = $(top_builddir)/libfreefare/libfreefare.la
+
 ntag_detect_SOURCES = ntag-detect.c
 ntag_detect_LDADD = $(top_builddir)/libfreefare/libfreefare.la
 

examples/mifare-ultralight-info.c

@@ -59,7 +59,28 @@ main(int argc, char *argv[])
  if (mifare_ultralight_connect(tag) < 0)
  errx(EXIT_FAILURE, "Error connecting to tag.");
  res = mifare_ultralightc_authenticate(tag, key);
- printf("Authentication with default key: %s\n", res ? "fail" : "success");
+ if (res != 0) {
+ MifareDESFireKey diversified_key = NULL;
+ MifareKeyDeriver deriver = mifare_key_deriver_new_an10922(key, MIFARE_KEY_2K3DES);
+
+ mifare_key_deriver_begin(deriver);
+ mifare_key_deriver_update_uid(deriver, tag);
+ diversified_key = mifare_key_deriver_end(deriver);
+
+ // Disconnect and reconnect.
+ mifare_ultralight_disconnect(tag);
+ if (mifare_ultralight_connect(tag) < 0)
+ errx(EXIT_FAILURE, "Error connecting to tag.");
+
+ res = mifare_ultralightc_authenticate(tag, diversified_key);
+
+ printf("Authentication with default key: %s\n", res ? "fail" : "success (diversified)");
+
+ mifare_desfire_key_free(diversified_key);
+ mifare_key_deriver_free(deriver);
+ } else {
+ printf("Authentication with default key: success\n");
+ }
  mifare_desfire_key_free(key);
  mifare_ultralight_disconnect(tag);
  }

examples/mifare-ultralightc-diversify.c

@@ -0,0 +1,112 @@
+#include <err.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <nfc/nfc.h>
+
+#include <freefare.h>
+
+static int
+swap_keys(FreefareTag tag, MifareDESFireKey new_key, MifareDESFireKey old_key)
+{
+ int res;
+ res = mifare_ultralightc_authenticate(tag, old_key);
+ MifareUltralightPage data;
+
+ if (res != 0) {
+ mifare_ultralight_disconnect(tag);
+ mifare_ultralight_connect(tag);
+ }
+
+ return mifare_ultralightc_set_key(tag, new_key);
+}
+
+int
+main(int argc, char *argv[])
+{
+ int error = EXIT_SUCCESS;
+ nfc_device *device = NULL;
+ FreefareTag *tags = NULL;
+ uint8_t key1_3des_data[16] = { 0x49, 0x45, 0x4D, 0x4B, 0x41, 0x45, 0x52, 0x42, 0x21, 0x4E, 0x41, 0x43, 0x55, 0x4F, 0x59, 0x46 };
+ MifareDESFireKey master_key = mifare_desfire_3des_key_new(key1_3des_data);
+ MifareDESFireKey derived_key = NULL;
+ MifareKeyDeriver deriver = mifare_key_deriver_new_an10922(master_key, MIFARE_KEY_2K3DES);
+ bool undiversify = (argc == 2 && strcmp("--undiversify",argv[1]) == 0);
+
+ if (argc > 2 || (argc == 2 && strcmp("--undiversify",argv[1]) != 0)) {
+ errx(EXIT_FAILURE, "usage: %s [--undiversify]", argv[0]);
+ }
+
+ nfc_connstring devices[8];
+ size_t device_count;
+
+ nfc_context *context;
+ nfc_init(&context);
+ if (context == NULL)
+ errx(EXIT_FAILURE, "Unable to init libnfc (malloc)");
+
+ device_count = nfc_list_devices(context, devices, sizeof(devices) / sizeof(*devices));
+ if (device_count <= 0)
+ errx(EXIT_FAILURE, "No NFC device found");
+
+ for (size_t d = 0; d < device_count; d++) {
+ if (!(device = nfc_open(context, devices[d]))) {
+ warnx("nfc_open() failed.");
+ error = EXIT_FAILURE;
+ continue;
+ }
+
+ if (!(tags = freefare_get_tags(device))) {
+ nfc_close(device);
+ errx(EXIT_FAILURE, "Error listing tags.");
+ }
+
+ for (int i = 0; (!error) && tags[i]; i++) {
+ int res;
+ FreefareTag tag = tags[i];
+ char *tag_uid = freefare_get_tag_uid(tag);
+
+ switch (freefare_get_tag_type(tag)) {
+ case MIFARE_ULTRALIGHT_C:
+ if (mifare_ultralight_connect(tag) < 0) {
+ errx(EXIT_FAILURE, "Error connecting to tag %s.", tag_uid);
+ }
+ break;
+ default:
+ continue;
+ }
+
+ if (mifare_key_deriver_begin(deriver) < 0) {
+ errx(EXIT_FAILURE, "Error starting key diversification");
+ }
+
+ if (mifare_key_deriver_update_uid(deriver, tag) < 0) {
+ errx(EXIT_FAILURE, "Error with key diversification");
+ }
+
+ if ((derived_key = mifare_key_deriver_end(deriver)) == NULL) {
+ errx(EXIT_FAILURE, "Error with key diversification");
+ }
+
+ if (undiversify) {
+ res = swap_keys(tag, master_key, derived_key);
+ } else {
+ res = swap_keys(tag, derived_key, master_key);
+ }
+
+ printf("%siversification of tag with UID %s %s.\n", undiversify?"Und":"D", tag_uid, res?"FAILED":"succeded");
+
+ mifare_desfire_key_free(derived_key);
+ mifare_ultralight_disconnect(tag);
+ free(tag_uid);
+ }
+
+ freefare_free_tags(tags);
+ nfc_close(device);
+ }
+
+ mifare_desfire_key_free(master_key);
+ mifare_key_deriver_free(deriver);
+ nfc_exit(context);
+ exit(error);
+}

libfreefare/CMakeLists.txt

@@ -10,6 +10,7 @@ set(LIBRARY_SOURCES
  mifare_desfire_crypto
  mifare_desfire_error
  mifare_desfire_key
+ mifare_key_deriver
  mifare_ultralight
  ntag21x
  tlv

libfreefare/Makefile.am

@@ -12,6 +12,7 @@ libfreefare_la_SOURCES = felica.c \
  mifare_desfire_crypto.c \
  mifare_desfire_error.c \
  mifare_desfire_key.c \
+ mifare_key_deriver.c \
  mad.c \
  mifare_application.c \
  ntag21x.c \
@@ -39,6 +40,7 @@ man_MANS = freefare.3 \
  mifare_desfire.3 \
  mifare_desfire_aid.3 \
  mifare_desfire_key.3 \
+ mifare_key_deriver.3 \
  mifare_ultralight.3 \
  ntag21x.3 \
  tlv.3

libfreefare/freefare.h

@@ -469,6 +469,7 @@ int mifare_desfire_set_configuration(FreefareTag tag, bool disable_format, boo
 int mifare_desfire_set_default_key(FreefareTag tag, MifareDESFireKey key);
 int mifare_desfire_set_ats(FreefareTag tag, uint8_t *ats);
 int mifare_desfire_get_card_uid(FreefareTag tag, char **uid);
+int mifare_desfire_get_card_uid_raw(FreefareTag tag, uint8_t uid[7]);
 int mifare_desfire_get_file_ids(FreefareTag tag, uint8_t **files, size_t *count);
 int mifare_desfire_get_iso_file_ids(FreefareTag tag, uint16_t **files, size_t *count);
 int mifare_desfire_get_file_settings(FreefareTag tag, uint8_t file_no, struct mifare_desfire_file_settings *settings);
@@ -521,6 +522,28 @@ uint8_t *tlv_decode(const uint8_t *istream, uint8_t *type, uint16_t *size);
 size_t tlv_record_length(const uint8_t *istream, size_t *field_length_size, size_t *field_value_size);
 uint8_t *tlv_append(uint8_t *a, uint8_t *b);
 
+typedef enum mifare_key_type {
+ MIFARE_KEY_DES,
+ MIFARE_KEY_2K3DES,
+ MIFARE_KEY_3K3DES,
+ MIFARE_KEY_AES128,
+
+ MIFARE_KEY_LAST = MIFARE_KEY_AES128
+} MifareKeyType;
+
+struct mifare_key_deriver;
+typedef struct mifare_key_deriver *MifareKeyDeriver;
+
+MifareKeyDeriver mifare_key_deriver_new_an10922(MifareDESFireKey master_key, MifareKeyType output_key_type);
+int mifare_key_deriver_begin(MifareKeyDeriver deriver);
+int mifare_key_deriver_update_data(MifareKeyDeriver deriver, const uint8_t *data, size_t len);
+int mifare_key_deriver_update_uid(MifareKeyDeriver deriver, FreefareTag tag);
+int mifare_key_deriver_update_aid(MifareKeyDeriver deriver, MifareDESFireAID aid);
+int mifare_key_deriver_update_cstr(MifareKeyDeriver deriver, const char *cstr);
+MifareDESFireKey mifare_key_deriver_end(MifareKeyDeriver deriver);
+int mifare_key_deriver_end_raw(MifareKeyDeriver deriver, uint8_t* diversified_bytes, size_t data_max_len);
+void mifare_key_deriver_free(MifareKeyDeriver state);
+
 #ifdef __cplusplus
 }
 #endif // __cplusplus

libfreefare/freefare_internal.h

@@ -185,12 +185,7 @@ struct mifare_desfire_aid {
 
 struct mifare_desfire_key {
  uint8_t data[24];
- enum {
- T_DES,
- T_3DES,
- T_3K3DES,
- T_AES
- } type;
+ MifareKeyType type;
  DES_key_schedule ks1;
  DES_key_schedule ks2;
  DES_key_schedule ks3;
@@ -215,6 +210,13 @@ struct mifare_desfire_tag {
  uint32_t selected_application;
 };
 
+struct mifare_key_deriver {
+ MifareDESFireKey master_key;
+ MifareKeyType output_key_type;
+ uint8_t m[48];
+ int len;
+};
+
 MifareDESFireKey mifare_desfire_session_key_new(const uint8_t rnda[], const uint8_t rndb[], MifareDESFireKey authentication_key);
 const char *mifare_desfire_error_lookup(uint8_t error);
 

libfreefare/mifare_desfire.c

@@ -437,14 +437,14 @@ int
 mifare_desfire_authenticate(FreefareTag tag, uint8_t key_no, MifareDESFireKey key)
 {
  switch (key->type) {
- case T_DES:
- case T_3DES:
+ case MIFARE_KEY_DES:
+ case MIFARE_KEY_2K3DES:
  return authenticate(tag, AUTHENTICATE_LEGACY, key_no, key);
  break;
- case T_3K3DES:
+ case MIFARE_KEY_3K3DES:
  return authenticate(tag, AUTHENTICATE_ISO, key_no, key);
  break;
- case T_AES:
+ case MIFARE_KEY_AES128:
  return authenticate(tag, AUTHENTICATE_AES, key_no, key);
  break;
  }
@@ -534,13 +534,13 @@ mifare_desfire_change_key(FreefareTag tag, uint8_t key_no, MifareDESFireKey new_
  */
  if (0x000000 == MIFARE_DESFIRE(tag)->selected_application) {
  switch (new_key->type) {
- case T_DES:
- case T_3DES:
+ case MIFARE_KEY_DES:
+ case MIFARE_KEY_2K3DES:
  break;
- case T_3K3DES:
+ case MIFARE_KEY_3K3DES:
  key_no |= 0x40;
  break;
- case T_AES:
+ case MIFARE_KEY_AES128:
  key_no |= 0x80;
  break;
  }
@@ -551,12 +551,12 @@ mifare_desfire_change_key(FreefareTag tag, uint8_t key_no, MifareDESFireKey new_
 
  int new_key_length;
  switch (new_key->type) {
- case T_DES:
- case T_3DES:
- case T_AES:
+ case MIFARE_KEY_DES:
+ case MIFARE_KEY_2K3DES:
+ case MIFARE_KEY_AES128:
  new_key_length = 16;
  break;
- case T_3K3DES:
+ case MIFARE_KEY_3K3DES:
  new_key_length = 24;
  break;
  }
@@ -573,7 +573,7 @@ mifare_desfire_change_key(FreefareTag tag, uint8_t key_no, MifareDESFireKey new_
 
  __cmd_n += new_key_length;
 
- if (new_key->type == T_AES)
+ if (new_key->type == MIFARE_KEY_AES128)
  cmd[__cmd_n++] = new_key->aes_version;
 
  if ((MIFARE_DESFIRE(tag)->authenticated_key_no & 0x0f) != (key_no & 0x0f)) {
@@ -1037,12 +1037,12 @@ mifare_desfire_set_default_key(FreefareTag tag, MifareDESFireKey key)
  BUFFER_APPEND(cmd, 0x01);
  size_t key_data_length;
  switch (key->type) {
- case T_DES:
- case T_3DES:
- case T_AES:
+ case MIFARE_KEY_DES:
+ case MIFARE_KEY_2K3DES:
+ case MIFARE_KEY_AES128:
  key_data_length = 16;
  break;
- case T_3K3DES:
+ case MIFARE_KEY_3K3DES:
  key_data_length = 24;
  break;
  }
@@ -1101,7 +1101,7 @@ mifare_desfire_set_ats(FreefareTag tag, uint8_t *ats)
 }
 
 int
-mifare_desfire_get_card_uid(FreefareTag tag, char **uid)
+mifare_desfire_get_card_uid_raw(FreefareTag tag, uint8_t uid[])
 {
  ASSERT_ACTIVE(tag);
 
@@ -1122,6 +1122,20 @@ mifare_desfire_get_card_uid(FreefareTag tag, char **uid)
  if (!p)
  return errno = EINVAL, -1;
 
+ memcpy(uid, p, 7);
+
+ return 0;
+}
+
+int
+mifare_desfire_get_card_uid(FreefareTag tag, char **uid)
+{
+ uint8_t p[7];
+
+ if (mifare_desfire_get_card_uid_raw(tag, p) < 0) {
+ return -1;
+ }
+
  if (!(*uid = malloc(2 * 7 + 1))) {
  return -1;
  }