KDE PIM/KItinerary/SBB Barcode
- QR code, content has variable length at around 330 bytes.
- Contains readable strings as well as binary parts.
- Seems to be a sequence of variable length records, rather than a fixed binary layout, could be some form of TLV encoding (there are some similarities to ASN.1 BER/DER for example).
- Records consist of a 1 byte type field, a length field and N content bytes.
- The type field does not seem to describe semantics, as values repeat for different values (rather than a data type of some form?). This would suggest that the record order defines their semantics. The presence of null records suggests that too, as well as the same record sequence in all samples.
- "European Union Agency For Railways - Technical Document - Digital Security Elements For Rail Passenger Ticketing - TAP TSI TD B.12 - §11 FCB - Flexible Content Barcode" describes something that seems similar, using ASN.1 UPER encoding.
- 1 byte type, although no idea what that indicates. Largely doesn't match the BER/DER type byte.
- for values <= 127 byte this is just one byte
- for value larger than 127 this is encoded in two bytes. This is quite different from BER/DER multi-byte length encoding however. It looks like a little endian layout , with the most significant bit of the first length byte being removed and the second byte being shifted by one bit to fill that space.
- N bytes of content, with varying data types.
- Strings seem to be UTF-8 encoded.
- The length is the amount of bytes needed to represent the UTF-8 string, not the amount of characters.
This is largely speculation at this point!
There's 5 7 byte sequences included that could be date/time values. These could be date of purchase/issue, begin of validity, end of validity, traveler birth date. All of those are printed on the ticket.
- the first byte is 0x08 in all samples
- the first half of the second byte seems to be 0x8 for date fields and 0xC for date/time fields. This would seem consistent with optional ASN.1 UPER field encoding.
- there's a surprising amount of entropy in those values, esp. when looking at differences at close-by dates.
- differential view shows no obvious correlation beyond multiple tickets, but close-by values do "look" similar nevertheless.
- the suspected birthday field is the same in all samples for the same traveler
- this does not seem to use a UNIX timestamp
- this does not seem to use BCD encoding
- this does not seem to use sub-byte per-component encoding
|Nesting Depth||Type Id||Content Type||Meaning||Notes|
|0||0x0A||date/time, nested record||?||speculative, given the 7 byte field there matches suspected date/time values below|
|2||0x0A||2bytes followed by nested records||?||0x08 04|
|3||0x12||string||ticket type?||"Point-to-point Ticket", "Supersaver Ticket"|
|2||0x20||2 byte||?||0x2801 in all samples|
|2||0x38||1 byte||?||0x42 in all samples|
|2||0x60||variable, null terminated||?||2-3 bytes in all samples, breaks TLV structure|
|2||0x7A||string||ticket type or tariff||parenthesis enclosed abbreviations, string is also printed on the ticket|
|2||0x88||1 byte||?||null, optional|
|1||0x1A||nested record||traveler information||could also be loyalty program info?|
|2||0x0A||string||SBB customer id||only the first 8 digits (of 10) though|
|2||0x12||string||Customer identifier||128 bit as a 36 byte hex string with for separator dashes (uuid-like formatting) Field tkid of https://www.swisspass.ch/private/api/benutzer/v1/benutzer|
|2||0x2A||7 byte||?||date/time? - possibly traveler birth date|
|2||0x10||4 byte||?||followed by 0x200B outside of TLV structures?|
|1||0x32||nested record||price information?|
|2||0x0A||string||payment method?||"PCD", "MC", "VIS"|
|1||0x42||nested record||train information||not present in unbound tickets|
|1||0x48||1 byte, no length byte!?!||?|
|0||0x12||2 byte||?||fixed 0x0801|
|1||0x0A||string||?||4 digit number (3342 in all samples)|
|1||0x12||string||?||5 digit number (00001 in all samples)|
|2||0x30||nested record||DSA signature in ASN.1/BER encoding, as found in UIC 918.3 containers as well|
|3||0x02||20-21 byte||r||DSA signature r value|
|3||0x02||20-21 byte||s||DSA signature s value|
This page was last edited on 22 February 2021, at 16:20. Content is available under Creative Commons License SA 4.0 unless otherwise noted.