//-----------------------------------------------------------------------------
// Frederik Möllers - August 2012
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Routines to support the German electronic "Personalausweis" (ID card)
// Note that the functions which do not implement USB commands do NOT initialize
// the card (with iso14443a_select_card etc.). If You want to use these
// functions, You need to do the setup before calling them!
//-----------------------------------------------------------------------------
#include "epa.h"
// Protocol and Parameter Selection Request for ISO 14443 type A cards
// use regular (1x) speed in both directions
// CRC is already included
static const uint8_t pps[] = {0xD0, 0x11, 0x00, 0x52, 0xA6};
// APDUs for communication with German Identification Card
// General Authenticate (request encrypted nonce) WITHOUT the Le at the end
static const uint8_t apdu_general_authenticate_pace_get_nonce[] = {
0x10, // CLA
0x86, // INS
0x00, // P1
0x00, // P2
0x02, // Lc
0x7C, // Type: Dynamic Authentication Data
0x00, // Length: 0 bytes
};
// MSE: Set AT (only CLA, INS, P1 and P2)
static const uint8_t apdu_mse_set_at_start[] = {
0x00, // CLA
0x22, // INS
0xC1, // P1
0xA4, // P2
};
// SELECT BINARY with the ID for EF.CardAccess
static const uint8_t apdu_select_binary_cardaccess[] = {
0x00, // CLA
0xA4, // INS
0x02, // P1
0x0C, // P2
0x02, // Lc
0x01, // ID
0x1C // ID
};
// READ BINARY
static const uint8_t apdu_read_binary[] = {
0x00, // CLA
0xB0, // INS
0x00, // P1
0x00, // P2
0x38 // Le
};
// the leading bytes of a PACE OID
static const uint8_t oid_pace_start[] = {
0x04, // itu-t, identified-organization
0x00, // etsi
0x7F, // reserved
0x00, // etsi-identified-organization
0x07, // bsi-de
0x02, // protocols
0x02, // smartcard
0x04 // id-PACE
};
// APDUs for replaying:
// MSE: Set AT (initiate PACE)
static uint8_t apdu_replay_mse_set_at_pace[41];
// General Authenticate (Get Nonce)
static uint8_t apdu_replay_general_authenticate_pace_get_nonce[8];
// General Authenticate (Map Nonce)
static uint8_t apdu_replay_general_authenticate_pace_map_nonce[75];
// General Authenticate (Mutual Authenticate)
static uint8_t apdu_replay_general_authenticate_pace_mutual_authenticate[75];
// General Authenticate (Perform Key Agreement)
static uint8_t apdu_replay_general_authenticate_pace_perform_key_agreement[18];
// pointers to the APDUs (for iterations)
static struct {
uint8_t len;
uint8_t *data;
} const apdus_replay[] = {
{sizeof(apdu_replay_mse_set_at_pace), apdu_replay_mse_set_at_pace},
{sizeof(apdu_replay_general_authenticate_pace_get_nonce), apdu_replay_general_authenticate_pace_get_nonce},
{sizeof(apdu_replay_general_authenticate_pace_map_nonce), apdu_replay_general_authenticate_pace_map_nonce},
{sizeof(apdu_replay_general_authenticate_pace_mutual_authenticate), apdu_replay_general_authenticate_pace_mutual_authenticate},
{sizeof(apdu_replay_general_authenticate_pace_perform_key_agreement), apdu_replay_general_authenticate_pace_perform_key_agreement}
};
// lengths of the replay APDUs
static uint8_t apdu_lengths_replay[5];
// type of card (ISO 14443 A or B)
static char iso_type = 0;
//-----------------------------------------------------------------------------
// Wrapper for sending APDUs to type A and B cards
//-----------------------------------------------------------------------------
int EPA_APDU(uint8_t *apdu, size_t length, uint8_t *response)
{
switch(iso_type)
{
case 'a':
return iso14_apdu(apdu, (uint16_t) length, response);
break;
case 'b':
return iso14443b_apdu(apdu, length, response);
break;
default:
return 0;
break;
}
}
//-----------------------------------------------------------------------------
// Closes the communication channel and turns off the field
//-----------------------------------------------------------------------------
void EPA_Finish()
{
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
LEDsoff();
iso_type = 0;
}
//-----------------------------------------------------------------------------
// Parses DER encoded data, e.g. from EF.CardAccess and fills out the given
// structs. If a pointer is 0, it is ignored.
// The function returns 0 on success and if an error occured, it returns the
// offset where it occured.
//
// TODO: This function can access memory outside of the given data if the DER
// encoding is broken
// TODO: Support skipping elements with a length > 0x7F
// TODO: Support OIDs with a length > 7F
// TODO: Support elements with long tags (tag is longer than 1 byte)
// TODO: Support proprietary PACE domain parameters
//-----------------------------------------------------------------------------
size_t EPA_Parse_CardAccess(uint8_t *data,
size_t length,
pace_version_info_t *pace_info)
{
size_t index = 0;
while (index <= length - 2) {
// determine type of element
// SET or SEQUENCE
if (data[index] == 0x31 || data[index] == 0x30) {
// enter the set (skip tag + length)
index += 2;
// check for extended length
if ((data[index - 1] & 0x80) != 0) {
index += (data[index-1] & 0x7F);
}
}
// OID
else if (data[index] == 0x06) {
// is this a PACE OID?
if (data[index + 1] == 0x0A // length matches
&& memcmp(data + index + 2,
oid_pace_start,
sizeof(oid_pace_start)) == 0 // content matches
&& pace_info != NULL)
{
// first, clear the pace_info struct
memset(pace_info, 0, sizeof(pace_version_info_t));
memcpy(pace_info->oid, data + index + 2, sizeof(pace_info->oid));
// a PACE OID is followed by the version
index += data[index + 1] + 2;
if (data[index] == 02 && data[index + 1] == 01) {
pace_info->version = data[index + 2];
index += 3;
}
else {
return index;
}
// after that there might(!) be the parameter ID
if (data[index] == 02 && data[index + 1] == 01) {
pace_info->parameter_id = data[index + 2];
index += 3;
}
}
else {
// skip this OID
index += 2 + data[index + 1];
}
}
// if the length is 0, something is wrong
// TODO: This needs to be extended to support long tags
else if (data[index + 1] == 0) {
return index;
}
else {
// skip this part
// TODO: This needs to be extended to support long tags
// TODO: This needs to be extended to support unknown elements with
// a size > 0x7F
index += 2 + data[index + 1];
}
}
// TODO: We should check whether we reached the end in error, but for that
// we need a better parser (e.g. with states like IN_SET or IN_PACE_INFO)
return 0;
}
//-----------------------------------------------------------------------------
// Read the file EF.CardAccess and save it into a buffer (at most max_length bytes)
// Returns -1 on failure or the length of the data on success
// TODO: for the moment this sends only 1 APDU regardless of the requested length
//-----------------------------------------------------------------------------
int EPA_Read_CardAccess(uint8_t *buffer, size_t max_length)
{
// the response APDU of the card
// since the card doesn't always care for the expected length we send it,
// we reserve 262 bytes here just to be safe (256-byte APDU + SW + ISO frame)
uint8_t response_apdu[262];
int rapdu_length = 0;
// select the file EF.CardAccess
rapdu_length = EPA_APDU((uint8_t *)apdu_select_binary_cardaccess,
sizeof(apdu_select_binary_cardaccess),
response_apdu);
if (rapdu_length < 6
|| response_apdu[rapdu_length - 4] != 0x90
|| response_apdu[rapdu_length - 3] != 0x00)
{
DbpString("Failed to select EF.CardAccess!");
return -1;
}
// read the file
rapdu_length = EPA_APDU((uint8_t *)apdu_read_binary,
sizeof(apdu_read_binary),
response_apdu);
if (rapdu_length <= 6
|| response_apdu[rapdu_length - 4] != 0x90
|| response_apdu[rapdu_length - 3] != 0x00)
{
Dbprintf("Failed to read EF.CardAccess!");
return -1;
}
// copy the content into the buffer
// length of data available: apdu_length - 4 (ISO frame) - 2 (SW)
size_t to_copy = rapdu_length - 6;
to_copy = to_copy < max_length ? to_copy : max_length;
memcpy(buffer, response_apdu+2, to_copy);
return to_copy;
}
//-----------------------------------------------------------------------------
// Abort helper function for EPA_PACE_Collect_Nonce
// sets relevant data in ack, sends the response
//-----------------------------------------------------------------------------
static void EPA_PACE_Collect_Nonce_Abort(uint8_t step, int func_return)
{
// power down the field
EPA_Finish();
// send the USB packet
cmd_send(CMD_ACK,step,func_return,0,0,0);
}
//-----------------------------------------------------------------------------
// Acquire one encrypted PACE nonce
//-----------------------------------------------------------------------------
void EPA_PACE_Collect_Nonce(UsbCommand *c)
{
/*
* ack layout:
* arg:
* 1. element
* step where the error occured or 0 if no error occured
* 2. element
* return code of the last executed function
* d:
* Encrypted nonce
*/
// return value of a function
int func_return = 0;
// set up communication
func_return = EPA_Setup();
if (func_return != 0) {
EPA_PACE_Collect_Nonce_Abort(1, func_return);
return;
}
// read the CardAccess file
// this array will hold the CardAccess file
uint8_t card_access[256] = {0};
int card_access_length = EPA_Read_CardAccess(card_access, 256);
// the response has to be at least this big to hold the OID
if (card_access_length < 18) {
EPA_PACE_Collect_Nonce_Abort(2, card_access_length);
return;
}
// this will hold the PACE info of the card
pace_version_info_t pace_version_info;
// search for the PACE OID
func_return = EPA_Parse_CardAccess(card_access,
card_access_length,
&pace_version_info);
if (func_return != 0 || pace_version_info.version == 0) {
EPA_PACE_Collect_Nonce_Abort(3, func_return);
return;
}
// initiate the PACE protocol
// use the CAN for the password since that doesn't change
func_return = EPA_PACE_MSE_Set_AT(pace_version_info, 2);
// now get the nonce
uint8_t nonce[256] = {0};
uint8_t requested_size = (uint8_t)c->arg[0];
func_return = EPA_PACE_Get_Nonce(requested_size, nonce);
// check if the command succeeded
if (func_return < 0)
{
EPA_PACE_Collect_Nonce_Abort(4, func_return);
return;
}
// all done, return
EPA_Finish();
// save received information
cmd_send(CMD_ACK,0,func_return,0,nonce,func_return);
}
//-----------------------------------------------------------------------------
// Performs the "Get Nonce" step of the PACE protocol and saves the returned
// nonce. The caller is responsible for allocating enough memory to store the
// nonce. Note that the returned size might be less or than or greater than the
// requested size!
// Returns the actual size of the nonce on success or a less-than-zero error
// code on failure.
//-----------------------------------------------------------------------------
int EPA_PACE_Get_Nonce(uint8_t requested_length, uint8_t *nonce)
{
// build the APDU
uint8_t apdu[sizeof(apdu_general_authenticate_pace_get_nonce) + 1];
// copy the constant part
memcpy(apdu,
apdu_general_authenticate_pace_get_nonce,
sizeof(apdu_general_authenticate_pace_get_nonce));
// append Le (requested length + 2 due to tag/length taking 2 bytes) in RAPDU
apdu[sizeof(apdu_general_authenticate_pace_get_nonce)] = requested_length + 4;
// send it
uint8_t response_apdu[262];
int send_return = EPA_APDU(apdu,
sizeof(apdu),
response_apdu);
// check if the command succeeded
if (send_return < 6
|| response_apdu[send_return - 4] != 0x90
|| response_apdu[send_return - 3] != 0x00)
{
return -1;
}
// if there is no nonce in the RAPDU, return here
if (send_return < 10)
{
// no error
return 0;
}
// get the actual length of the nonce
uint8_t nonce_length = response_apdu[5];
if (nonce_length > send_return - 10)
{
nonce_length = send_return - 10;
}
// copy the nonce
memcpy(nonce, response_apdu + 6, nonce_length);
return nonce_length;
}
//-----------------------------------------------------------------------------
// Initializes the PACE protocol by performing the "MSE: Set AT" step
// Returns 0 on success or a non-zero error code on failure
//-----------------------------------------------------------------------------
int EPA_PACE_MSE_Set_AT(pace_version_info_t pace_version_info, uint8_t password)
{
// create the MSE: Set AT APDU
uint8_t apdu[23];
// the minimum length (will be increased as more data is added)
size_t apdu_length = 20;
// copy the constant part
memcpy(apdu,
apdu_mse_set_at_start,
sizeof(apdu_mse_set_at_start));
// type: OID
apdu[5] = 0x80;
// length of the OID
apdu[6] = sizeof(pace_version_info.oid);
// copy the OID
memcpy(apdu + 7,
pace_version_info.oid,
sizeof(pace_version_info.oid));
// type: password
apdu[17] = 0x83;
// length: 1
apdu[18] = 1;
// password
apdu[19] = password;
// if standardized domain parameters are used, copy the ID
if (pace_version_info.parameter_id != 0) {
apdu_length += 3;
// type: domain parameter
apdu[20] = 0x84;
// length: 1
apdu[21] = 1;
// copy the parameter ID
apdu[22] = pace_version_info.parameter_id;
}
// now set Lc to the actual length
apdu[4] = apdu_length - 5;
// send it
uint8_t response_apdu[6];
int send_return = EPA_APDU(apdu,
apdu_length,
response_apdu);
// check if the command succeeded
if (send_return != 6
|| response_apdu[send_return - 4] != 0x90
|| response_apdu[send_return - 3] != 0x00)
{
return 1;
}
return 0;
}
//-----------------------------------------------------------------------------
// Perform the PACE protocol by replaying given APDUs
//-----------------------------------------------------------------------------
void EPA_PACE_Replay(UsbCommand *c)
{
uint32_t timings[sizeof(apdu_lengths_replay) / sizeof(apdu_lengths_replay[0])] = {0};
// if an APDU has been passed, save it
if (c->arg[0] != 0) {
// make sure it's not too big
if(c->arg[2] > apdus_replay[c->arg[0] - 1].len)
{
cmd_send(CMD_ACK, 1, 0, 0, NULL, 0);
}
memcpy(apdus_replay[c->arg[0] - 1].data + c->arg[1],
c->d.asBytes,
c->arg[2]);
// save/update APDU length
if (c->arg[1] == 0) {
apdu_lengths_replay[c->arg[0] - 1] = c->arg[2];
} else {
apdu_lengths_replay[c->arg[0] - 1] += c->arg[2];
}
cmd_send(CMD_ACK, 0, 0, 0, NULL, 0);
return;
}
// return value of a function
int func_return;
// set up communication
func_return = EPA_Setup();
if (func_return != 0) {
EPA_Finish();
cmd_send(CMD_ACK, 2, func_return, 0, NULL, 0);
return;
}
// increase the timeout (at least some cards really do need this!)/////////////
// iso14a_set_timeout(0x0003FFFF);
// response APDU
uint8_t response_apdu[300] = {0};
// now replay the data and measure the timings
for (int i = 0; i < sizeof(apdu_lengths_replay); i++) {
StartCountUS();
func_return = EPA_APDU(apdus_replay[i].data,
apdu_lengths_replay[i],
response_apdu);
timings[i] = GetCountUS();
// every step but the last one should succeed
if (i < sizeof(apdu_lengths_replay) - 1
&& (func_return < 6
|| response_apdu[func_return - 4] != 0x90
|| response_apdu[func_return - 3] != 0x00))
{
EPA_Finish();
cmd_send(CMD_ACK, 3 + i, func_return, 0, timings, 20);
return;
}
}
EPA_Finish();
cmd_send(CMD_ACK,0,0,0,timings,20);
return;
}
//-----------------------------------------------------------------------------
// Set up a communication channel (Card Select, PPS)
// Returns 0 on success or a non-zero error code on failure
//-----------------------------------------------------------------------------
int EPA_Setup()
{
int return_code = 0;
uint8_t uid[10];
uint8_t pps_response[3];
uint8_t pps_response_par[1];
iso14a_card_select_t card_a_info;
iso14b_card_select_t card_b_info;
// first, look for type A cards
// power up the field
iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
// select the card
return_code = iso14443a_select_card(uid, &card_a_info, NULL, true, 0, false);
if (return_code == 1) {
// send the PPS request
ReaderTransmit((uint8_t *)pps, sizeof(pps), NULL);
return_code = ReaderReceive(pps_response, pps_response_par);
if (return_code != 3 || pps_response[0] != 0xD0) {
return return_code == 0 ? 2 : return_code;
}
Dbprintf("ISO 14443 Type A");
iso_type = 'a';
return 0;
}
// if we're here, there is no type A card, so we look for type B
// power up the field
iso14443b_setup();
// select the card
return_code = iso14443b_select_card( &card_b_info );
if (return_code == 1) {
Dbprintf("ISO 14443 Type B");
iso_type = 'b';
return 0;
}
Dbprintf("No card found.");
return 1;
}