proxmark3/armsrc/epa.c
frederikmoellers@aol.de e5ad43c07e Power down the field before sending the USB ACK
This fixes the bug that the USB communication breaks when collecting PACE nonces with no delay. The delay functionality has not been removed (it doesn't hurt to keep it), but using a delay of 0 is now possible without a high risk of getting too many errors.
2012-09-01 23:54:38 +00:00

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13 KiB
C

//-----------------------------------------------------------------------------
// 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 eletronic "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 "iso14443a.h"
#include "epa.h"
// Protocol and Parameter Selection Request
// 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
};
//-----------------------------------------------------------------------------
// Closes the communication channel and turns off the field
//-----------------------------------------------------------------------------
void EPA_Finish()
{
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
LEDsoff();
}
//-----------------------------------------------------------------------------
// 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;
// extended length
if ((data[index - 1] & 0x80) != 0) {
index += (data[index] & 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 = iso14_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)
{
return -1;
}
// read the file
rapdu_length = iso14_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)
{
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(UsbCommand *ack, uint8_t step, int func_return)
{
// step in which the failure occured
ack->arg[0] = step;
// last return code
ack->arg[1] = func_return;
// power down the field
EPA_Finish();
// send the USB packet
UsbSendPacket((void *)ack, sizeof(UsbCommand));
}
//-----------------------------------------------------------------------------
// Acquire one encrypted PACE nonce
//-----------------------------------------------------------------------------
void EPA_PACE_Collect_Nonce(UsbCommand *c, UsbCommand *ack)
{
/*
* 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;
// initialize ack with 0s
memset(ack->arg, 0, 12);
memset(ack->d.asBytes, 0, 48);
// set up communication
func_return = EPA_Setup();
if (func_return != 0) {
EPA_PACE_Collect_Nonce_Abort(ack, 1, func_return);
return;
}
// increase the timeout (at least some cards really do need this!)
iso14a_set_timeout(0x0002FFFF);
// 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(ack, 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(ack, 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(ack, 4, func_return);
return;
}
// save received information
ack->arg[1] = func_return;
memcpy(ack->d.asBytes, nonce, func_return);
// all done, return
EPA_Finish();
UsbSendPacket((void *)ack, sizeof(UsbCommand));
}
//-----------------------------------------------------------------------------
// 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 = iso14_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 = iso14_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;
}
//-----------------------------------------------------------------------------
// Set up a communication channel (Card Select, PPS)
// Returns 0 on success or a non-zero error code on failure
//-----------------------------------------------------------------------------
int EPA_Setup()
{
// return code
int return_code = 0;
// card UID
uint8_t uid[8];
// card select information
iso14a_card_select_t card_select_info;
// power up the field
iso14443a_setup();
// select the card
return_code = iso14443a_select_card(uid, &card_select_info, NULL);
if (return_code != 1) {
return 1;
}
// send the PPS request
ReaderTransmit((uint8_t *)pps, sizeof(pps));
uint8_t pps_response[3];
return_code = ReaderReceive(pps_response);
if (return_code != 3 || pps_response[0] != 0xD0) {
return return_code == 0 ? 2 : return_code;
}
return 0;
}