(Bit Layout)
(Bit Layout)
Line 23: Line 23:
 
| 4:7 - 5:7 || 9 bit day number ||  || day of travel, counted from Jan 1
 
| 4:7 - 5:7 || 9 bit day number ||  || day of travel, counted from Jan 1
 
|-
 
|-
| 6 - 12 || 0x00 0x49 0x24 0x92 0x49 0x24 0x92 || || fixed in all samples
+
| 6 - 12 || 0x00 0x49 0x24 0x92 0x49 0x24 0x92 || || fixed in all samples, patterns repeats below
 
|-
 
|-
| 13 - 42:0 || todo || todo ||
+
| 13 - 31 || todo || todo ||
 +
|-
 +
| 32 - 40 || 0x89 0x24 0x92 0x49 0x24 0x90 0x60 0x00 0x01 || || fixed in all samples, repeats a pattern from 6-12
 +
|-
 +
| 41:0 - 42:0 || todo || todo || varies slightly between samples
 
|-
 
|-
 
| 42:1 - 106:0 || 64 byte varying || || high entropy in all samples, signature?
 
| 42:1 - 106:0 || 64 byte varying || || high entropy in all samples, signature?

Revision as of 17:34, 4 January 2020

General Observations

  • always exactly 107 byte
  • all binary, there are no recognizable ASCII strings in this
  • the last ~64 byte have very high entropy, suggesting a signature or a compressed section
  • there's a base64 encoded sequential number printed below the Aztec code on the ticket, containing 24bit.
  • one barcode seems to be exactly for one journey section

Bit Layout

Byte[:Bit] (MSB) Content Meaning Notes
0 - 1 0b0001 0000 0b0000 0010 unknown fixed in all samples
2 0b1010 0000 or 0b1000 0000 unknown
3 0b0000 0001 unknown fixed in all samples
4:0 4:6 null
4:7 - 5:7 9 bit day number day of travel, counted from Jan 1
6 - 12 0x00 0x49 0x24 0x92 0x49 0x24 0x92 fixed in all samples, patterns repeats below
13 - 31 todo todo
32 - 40 0x89 0x24 0x92 0x49 0x24 0x90 0x60 0x00 0x01 fixed in all samples, repeats a pattern from 6-12
41:0 - 42:0 todo todo varies slightly between samples
42:1 - 106:0 64 byte varying high entropy in all samples, signature?
106:1 - 106:7 null

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