# how to predict a sequence for reverse engineering of a ticketing system [closed]

i am student in the fith year of college IT-science and a crypto noob.

i have been wondering how the folwing sequence of ticket i bougth in all at once were built for : how they work or how they are built ?

it look like a predictable sequence made of:

• Prefix (type of ticket)
• FRAW21LV0001EFRFR021B4TIE28 00010NN50000000000
• FRAW21LV0002SFRFR021B4TIE28 00010NN50000000000
• FRAW21LV0006YFRFR021B4TIE28 00010NN50000000000
• Sequence number(base 26) from: 14J0000 to: 1780000
• Constante string : 7QC00
• unknow/Hash/MAC/CRC of 7 char starts with 0 or 1
• ticket_id*2 (even number) length of 9 to 10 char

tickets as they are printed

type 1

FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014E00007QC000I3V1H100000004
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014F00007QC0012Y8WM900000006
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014G00007QC001UPS4G500000008
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014H00007QC00132GGIH000000010
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014I00007QC001FMQSVS000000012
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014J00007QC0019774UI000000014
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014K00007QC000LUJ6VS000000016
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014L00007QC000IMOYOZ000000018
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014M00007QC0002ZDAX5000000020
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014N00007QC000ROEAU7000000022
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014O00007QC000OJAU6T000000024
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014P00007QC000FV70PE000000026
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014Q00007QC001VYVGPI000000028
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014R00007QC001A2G3RG000000030
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014S00007QC000536TKS000000032
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014T00007QC000TS3HI6000000034
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014U00007QC000FQUU74000000036
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014V00007QC001C7LT43000000038
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014W00007QC000BWG4TL000000040
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014X00007QC000Y7RB9M000000042
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014Y00007QC000Z6UZU2000000044
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000014Z00007QC0003N8GOF000000046
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015000007QC000XRUGSS000000048
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015100007QC0011NMAOX000000050
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015200007QC001VHWA7Q000000052
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015300007QC0019I8TY9000000054
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015400007QC001KGJIS0000000056
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015500007QC0006ZSI03000000058
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015600007QC0015AHWQP000000060
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015700007QC001WIFHGU000000062
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015800007QC001DX8NP5000000064
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015900007QC0019BDRGP000000066
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015A00007QC00189GE0R000000068
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015B00007QC001PSYIRO000000070
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015C00007QC0008ALR18000000072
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015D00007QC000PEE4N8000000074
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015E00007QC000MC9TCS000000076
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015F00007QC00172UW26000000078
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015G00007QC000V6MCOS000000080
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015H00007QC0008SU4TW000000082
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015I00007QC001V0V374000000084
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015J00007QC000AOFB24000000086
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015K00007QC000QZZEUD000000088
FRAW21LV0001EFRFR021B4TIE28 00010NN5000000000015L00007QC000P803AU000000090


ticket type 2

FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000015W00007QC0005CBZFX0000000112
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000015X00007QC0004DPHHL0000000114
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000015Y00007QC000X7NCG70000000116
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000015Z00007QC001JZ6DL00000000118
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016000007QC001LLJI8S0000000120
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016100007QC00166HTZC0000000122
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016200007QC001R3U5ZB0000000124
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016300007QC001PYRX9Z0000000126
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016400007QC0006F1EDQ0000000128
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016500007QC001B26VOL0000000130
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016600007QC000Y5RU2V0000000132
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016700007QC001DMIVHO0000000134
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016800007QC001XHE8QE0000000136
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016900007QC000E4Q31W0000000138
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016A00007QC000FX6R2I0000000140
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016B00007QC000RU5HDD0000000142
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016D00007QC000CMKEDA0000000146
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016E00007QC0003H2RH20000000148
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016F00007QC001HC4UMN0000000150
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016G00007QC001SNRY2B0000000152
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016H00007QC000GJIRGH0000000154
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016I00007QC0017R68XG0000000156
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016J00007QC001PZK5GC0000000158
FRAW21LV0002SFRFR021B4TIE28 00010NN5000000000016K00007QC000IJOLIO0000000160


type 3

FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016L00007QC0017MKPS90000000162
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016M00007QC001IZUAM20000000164
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016N00007QC001LJY2P80000000166
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016O00007QC001YAOS710000000168
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016P00007QC000FX78CH0000000170
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016Q00007QC0006OA5R00000000172
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016R00007QC000695XFR0000000174
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016S00007QC000CYSCN80000000176
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016T00007QC0015BHDEJ0000000178
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016U00007QC001LWHV080000000180
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016V00007QC000TW27RX0000000182
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016W00007QC00008P74H0000000184
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016X00007QC0001D51PO0000000186
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016Y00007QC0012WKJEG0000000188
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000016Z00007QC000PGXY7F0000000190
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017000007QC000UJG6HI0000000192
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017100007QC001YLI34V0000000194
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017200007QC000DSIIOV0000000196
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017300007QC001RN1XX80000000198
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017400007QC000CBRC7B0000000200
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017500007QC0007LW3ZA0000000202
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017600007QC000GF4KGP0000000204
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017700007QC000ULKRDP0000000206
FRAW21LV0006YFRFR021B4TIE28 00010NN5000000000017800007QC0008WGFZN0000000208


question :

1. i am Assuming there is a finit set of off the shelf hash or crc Algo.
2. How secure is this?
3. is my guess correct and if what kind of hashing alghorthm is?
4. is there a way & how to figure out how the hash/CRC is computed given this large amount or even a larger amount of ticket? asumming no salt is added and off the shelf algo is used.
5. question 4 also implies finding witch charters are used to compute the hash ?
• We don't waste our effort doing cryptanalysis on any schemes - it's time consuming, and the result are rarely useful to us or to anyone else. You can take a tour of our site by clicking on the round-enclosed question mark to the top right of the page and learn more about what we ask and answer on this site. – DannyNiu Apr 13 '20 at 7:09

1. there is a finite set of off-the-shelf hash or CRC algorithms.

There are few dozen hashes in common use, and hundreds of CRCs (often involuntary variations of standard CRC). However, designers would have been naive to use something common, and may and should have used a Message Authentication Code. This has a secret key. Without it, the output of the MAC is indistinguishable from that of a random function of the message authenticated.

1. How secure is this?

It can only be told by breaking it at least partially, or obtaining more information about the design.

1. is there a way & how to figure out how the hash/CRC is computed given this large amount or even a larger amount of ticket? assuming no salt is added and off the shelf algo is used.

This has been presented as a real ticketing system, and while my bets are on homework or a CTF, as a matter of policy I won't help.

• since it is trivial to copy a simple ticket ticket. My guess is the system would detetc a second entry of the same ticket number... it seems the designer should have bee nusing some kind of public/private key design instead ot that – pabx06 Apr 13 '20 at 7:48