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uFCoder library Machine Readable Travel Documents (MRTD) support

Introduction #

Support for reading data groups from the NFC tag embedded in the Machine Readable Travel Documents (MRTDs), including ePassports that comply with ICAO specifications, has been implemented in the uFCoder library.

The implementation supports the Basic Access Control (BAC) mechanism for NFC chip access. BAC enables authentication and a secure cryptographic communication channel with an NFC tag embedded in the MRTD. BAC is based purely on symmetric cryptography using the 3DES algorithm and it is implemented according to ICAO 9303, part 11.

ICAO stands for International Civil Aviation Organization (https://www.icao.int). ICAO 9303 specification standardizes MRTDs, including ePassports. You can find the entire ICAO Doc 9303 series on https://www.icao.int/publications/pages/publication.aspx?docnum=9303web location.

MRTDs Basic Access Control is supported in the uFCoder library from version 5.0.12.

In order to authenticate to the NFC tag embedded in the MRTD first, you have to pass the document number, the birth date of the document holder, and document expiration date to function MRTD_MRZDataToMRZProtoKey() in order to get the “proto key” from which will be derived other necessary security keys. All the data needed to get “proto key” (document number, the birth date of the document holder, and document expiration date) are encoded in Machine Readable Zone (MRZ) so the library has MRTD_MRZSubjacentToMRZProtoKey() function which can be called instead of MRTD_MRZDataToMRZProtoKey(). This function accepts a null-terminated string containing a subjacent row of the document MRZ. The screenshot below shows an example of the MRZ with a marked subjacent row which content you have to pass as a parameter to function MRTD_MRZSubjacentToMRZProtoKey().

epassport MRZ

MRTD support library functions #

MRTD_MRZDataToMRZProtoKey #

Function description

In order to get MRZ Proto Key needed in subsequent steps, you can call this function and pass it null-terminated strings containing document number, document holder date of birth, and document expiration date. After successful function execution, MRZ Proto Key will be stored in a mrz_proto_key 25-byte array.

A function declaration (C language)

UFR_STATUS MRTD_MRZDataToMRZProtoKey(const char *doc_number,

const char *date_of_birth,

const char *date_of_expiry,

uint8_t mrz_proto_key[25]);

Parameters

doc_number Pointer to a null-terminated string containing exactly 9 characters document number.
date_of_birth Pointer to a null-terminated string containing exactly 6 characters representing the date of birth in the “YYMMDD” format.
date_of_expiry Pointer to a null-terminated string containing exactly 6 characters representing expiration date in the “YYMMDD” format.
mrz_proto_key This byte array will contain the calculated MRZ proto-key after successful function execution. This array must have allocated at least 25 bytes prior to calling this function.

 

MRTD_MRZSubjacentToMRZProtoKey #

Function description

In order to get the MRZ Proto Key needed in subsequent steps, in the case of the TD3 MRZ format (88 totally characters long), you can call this function and pass it a null-terminated string containing MRZ subjacent row. An example of the TD3 MRZ format printed on the eMRTD document looks like this:

P<UTOERIKSSON<<ANNA<MARIA<<<<<<<<<<<<<<<<<<<

L898902C36UTO7408122F1204159ZE184226B<<<<<10

This function should receive a pointer to a null-terminated string containing MRZ subjacent row i.e. “L898902C36UTO7408122F1204159ZE184226B<<<<<10”.

Function declaration (C language)

UFR_STATUS MRTD_MRZSubjacentToMRZProtoKey(const char *mrz, uint8_t mrz_proto_key[25]);

Parameters  
mrz Pointer to a null-terminated string containing MRZ data. According to ICAO Doc 9303-10, where it has three MRZ data formats: TD1, TD2, or TD3 formats. TD1 contains exactly 90 characters, TD2 contains exactly 72 characters and TD3 contains exactly 88 characters.
mrz_proto_key This byte array will contain the calculated MRZ proto-key after successful function execution. This array must have allocated at least 25 bytes prior call this function.

MRTDAppSelectAndAuthenticateBac #

Function description

Use this function to authenticate to the eMRTD NFC tag using BAC. This function establishes a secure channel for communication. The security channel is maintained using the send_sequence_cnt parameter. The channel session keys are ksenc (for encryption) and ksmac (for calculating MAC).

Function declaration (C language)

UFR_STATUS MRTDAppSelectAndAuthenticateBac(const uint8_t mrz_proto_key[25], uint8_t ksenc[16],

uint8_t ksmac[16],

uint64_t *send_sequence_cnt);

Parameters

mrz_proto_key MRZ proto-key acquired using the prior call to MRTD_MRZDataToMRZProtoKey() or MRTD_MRZSubjacentToMRZProtoKey() functio
ksenc This array must have allocated at least 16 bytes prior call this function. This array will contain session encryption key after successful function execution
ksmac This array must have allocated at least 16 bytes prior to calli this function. This array will contain a session key for calculating MAC after successful function execution.
send_sequence_cnt After successful execution of this function, the pointer to this 64-bit value should be saved and forwarded at every subsequent call to MRTDFileReadBacToHeap() and/or other functions for reading eMRTD

MRTDFileReadBacToHeap #

Function description

Use this function to read files from the eMRTD NFC tag. You can call this function only after successfully established a security channel by the previously called

MRTDAppSelectAndAuthenticateBac() function. Session keys ksenc and ksmac, and also parameter send_sequence_cnt are acquired by the previously called

MRTDAppSelectAndAuthenticateBac() function. After the successful call to this function, *output points to the file data read from an eMRTD file specified by the file_index parameter. Buffer, in which the data is stored, is automatically allocated on memory heap during function execution. The maximum amount of data allocated can be 32KB. There is the programmer’s responsibility to clean up allocated data (i.e. by calling free(), the standard C function) after use.

Function declaration (C language)

UFR_STATUS MRTDFileReadBacToHeap(const uint8_t *file_index,

uint8_t **output,

uint32_t *output_length,

const uint8_t ksenc[16],

const uint8_t ksmac[16],

Parameters

file_index

The parameter that specifies the file we want to read from the eMRTD. This is a pointer to a byte array contains exactly two bytes designating the eMRTD file. Those two bytes are file identification (FID) and there is a list of FIDs:

EF.COM = {0x01, 0x1E}
EF.DG1 = {0x01, 0x01}
EF.DG2 = {0x01, 0x02}
EF.DG3 = {0x01, 0x03}
EF.DG4 = {0x01, 0x04}
EF.DG5 = {0x01, 0x05}
EF.DG6 = {0x01, 0x06}
EF.DG7 = {0x01, 0x07}
EF.DG8 = {0x01, 0x08}
EF.DG9 = {0x01, 0x09}
EF.DG10 = {0x01, 0x0A}
EF.DG11 = {0x01, 0x0B}
EF.DG12 = {0x01, 0x0C}
EF.DG13 = {0x01, 0x0D}
EF.DG14 = {0x01, 0x0E}
EF.DG15 = {0x01, 0x0F}
EF.DG16 = {0x01, 0x10}
EF.SOD = {0x01, 0x1D}

*output After the successful call to this function, this pointer points to the file data read from an eMRTD file specified by the file_index parameter. Buffer, in which the data is stored, is automatically allocated during function execution. The maximum amount of data allocated can be 32KB. There is the programmer’s responsibility to clean up allocated data (i.e. by calling free(), the standard C function) after use.
output_length After the successful call to this function, this pointer is pointing to the size of the file data read from an eMRTD file specified by the file_index parameter.
ksenc Session encryption key acquired using a prior call to MRTDAppSelectAndAuthenticateBac() function.
ksmac The session key for calculating MAC acquired using a prior call to MRTDAppSelectAndAuthenticateBac() function.
send_sequence_cnt This pointer should point to a 64-bit value initialized by the previously
successful call to MRTDAppSelectAndAuthenticateBac() function. Pointer to this 64-bit value should be saved and forwarded at every subsequent call to this function and/or other functions used for reading eMRTD.

uint64_t *send_sequence_cnt);

 

ePassport MRTD Example #

This example you can download from:

https://www.d-logic.net/code/nfc-rfid-reader-sdk/ufr-examples-ePassport_mrtd.git

or clone the entire eclipse CDT project using:

git clone –recursive https://www.d-logic.net/code/nfc-rfid-reader-sdk/ufr-examples-ePassport_mrtd.git

command.

If you want quick run only, download the project and start binary executable from the appropriate folder:

  • for a 32-bit Windows start the win32_release\run_me.cmd
  • for a 64-bit Windows start the win64_release\run_me.cmd
  • for a 32-bit Linux start linux32_release/ePassport_mrtd
  • for a 64-bit Linux start linux64_release/ePassport_mrtd.

Software example requires uFR reader device to be attached and configured to the PC. No other application or service using uFR reader should be running on the computer. After the successful start of the “ePassport MRTD Example,” the software starts the main many as shown below.

ePassport reader MRTD NFC

<“>Now, you should choose one of the ‘M’ or ‘P’ options as stated in the application usage instructions on the screen.

If you chose the ‘M’ option, you will be prompted with text:

You have chose to enter subjacent MRZ row located under the ‘P<XXXSURNAME<<FIRSTNAME<<<<<<<<<<<<<<<<<<<<<‘:

Enter subjacent MRZ row. Subjacent MRZ row have to be 44 characters long.

so enter subjacent MRZ row. An example of the subjacent MRZ row can see in the first image.

Otherwise, if you chose the ‘P’ option you will be prompted with text:

You have chosen to enter the doc. number, date of birth, and date of expiry separately:

Enter the document number. The document number should be 9 characters long.

_________ …

Enter the date of birth. Date format has to be YYMMDD.

______ …

Enter the date of expiry. Date format has to be YYMMDD.

______ …

so enter the data in the appropriate format.

After you have entered the valid data, the application will inform you with a message:

MRZ proto-key has been set successfully.

——————————————————————-

After this message, you can continue with reading operations on the NFC tag embedded into ePassport that data you have previously entered belongs to.

Now you can put the passport in the uFR reader field. On successful communication established you will get basic information about the NFC tag in the reader field. For example:

——————————————————————-

Tag type: DL_GENERIC_ISO14443_4, sak = 0x??, uid[4] = ??:??:??:??

——————————————————————-

SAK and UID in this example are masked and they can have any arbitrary value. ePassports will be always be recognized like DL_GENERIC_ISO14443_4 tag type.

Now you can choose application reading options:

C’ – this option reads common data (EF.COM elementary file) from the ePassport. After a successful reading, data is parsed and displayed in the following format:

EF.COM has been successfully read. The file length is ?? bytes

Raw data: 60 xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx …

Parsing the EF.COM raw data:

LDS version is 01.07

UNICODE version is 04.00.00

Existing data groups list:

Found: EF.DG1

Found: EF.DG2

Found: EF.DG3

Found: EF.DG14

——————————————————————-

Raw data in this example are masked and they can have any arbitrary value. Only the raw data tag has been present and it will be always the same (0x60). When you read your own document, you will get its actual raw data here. More about the LDS version and UNICODE version you can read in the ICAO 9303, part 10 document.

LDS and UNICODE versions is followed by the data groups list that ePassport contains. Only DG1 and DG2 are mandatory. All the other data groups can be either present or not in the particular MRTD.

S’ – this option reads the document security object (EF.SO elementary file) and saves it to the binary file which path and name you have to enter when you prompted. Document security object contains a digital signature in the standard PKCS#7CMSformat. Presence of the EF.SO on the MRTD is mandatory.

D

1’– this option reads the EF.DG1, parse it and displays raw and parsed data in the following format:

EF.DG1 has been successfully read. File length is ?? bytes

Raw data:

61 xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx

  1. xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx  

Simple parsing the EF.DG1 raw data:

Document code: P (ePassport)

Issuing State or organization: ???

Name of the holder: SURNAME FIRST_NAME

Document number: ?????????

Nationality: ???

Date of birth (dd.MM.yyyy.): ??.??.????.

Sex: ????

Date of expiry (dd.MM.yyyy.): ??.??.????.

Optional data: ??????????????

——————————————————————-

Raw data in this example are masked and they can have any arbitrary value. Only the raw data tag has been present and it will be always the same (0x61). When you read your own document, you will get its actual raw data here.

2’ – this option reads the EF.DG2 and save it to the binary file which path and name you have to enter when you prompted. EF.DG2 contains a document holder facial image and it is mandatory. EF.DG2 beside facial image could contain biometric facial features too. More about EF.DG2 content you can read in the ICAO 9303, part 10 document.

I’ – this option reads the EF.DG2 to. In this case, only the facial image is extracted from the MRTD file and saved to the file which path and name you have entered. The image format is automatically detected and the file extension is set according to it. There are two possible image file formats defined for this context: JPEG or JP2 (i.e. jpeg 2000).

D’ – this option reads any of the elementary data group (EF.DG) files from the MRTD and saves it to the binary file which path and name you have to enter when you prompted. After this option has been chosen you will be prompted for EF.DG index. The index can be from the range 1 to 16 (e.g. 1 for EF.DG1 and 14 for EF.DG14). The elementary file you wanted to read must be listed in the EF.COM data groups list.

Reading of some optional elementary files, especially those containing biometric data, requires special security mechanisms that are outside the scope of this document.

The current version of the “ePassport MRTD Example” is 1.0 and depends on the uFCoder library version 5.0.12 and uFR firmware version 5.0.22.