Passcode Decoding Walkthrough #003.2

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Passcode Walkthrough for Niantic Project Post 2014-02-01 passcode#2

 

Decoding Tools

http://tools.decodeingress.me/

http://decodeingress.me/tools/

The 3 most common passcode formats are:

Long Passcode Format 1 (Mostly for the retired Niantic Investigation Board). This format seems to be deprecated. [2-9][p-z][a-h][2-9]keyword[p-z][2-9][p-z][2-9][p-z]

Long Passcode Format 2 (Mostly for JOJO Word of the Day WOTD or Cheshire Cat posts) [2-9][p-z][p-z][a-h][2-9]keyword[p-z][2-9][2-9][2-9][p-z]

Long Passcode Format 3 (Mostly for Niantic Project document posts) [2-9][a-z][a-z][a-z][2-9]keyword[a-z][2-9][a-z][2-9][a-z]

 

Difficulty Rating: (out of 8. 1-5 are regular difficulty levels, 6-8 are very challenging):

Document and Source:

Niantic sometimes releases ciphers in platforms other than Google+, like Facebook, Twitter, Youtube or Soundcloud. On 1 February, several tweets containing ciphers were released.

How/where to find the source of the passcode:

In the tweet linked to above, there are two ostensibly separate ciphers. We will look at the first one of these: bbbbbbdddcfdibbbccbdbdbcbbcbbedbebdccbbbbdbccdcdfcbdbdbccccbbbbccdcbcbbbcbccccb

Methods/Process:

Working with numbers is my strength, so my first instinct was to replace each letter with a number (a=1, b=2, etc) to obtain:

2222224443649222332424232232254252433222242334346324242333322223343232223233332

This looks very much like run-length encoding of a binary string. However, there are several aspects that is bothersome:

  • The sum of the digits (which equals the length of the decoded bit string) is equal to 231, which is not a multiple of 8 (as one would expect in an 8-bit binary encoding), nor a multiple of 7 (as one would expect in a 7-bit binary encoding) nor two more than a multiple of 11 (as one would expect in a barcode encoding).

  • There is a digit 9, which is unusual (though not impossible) for a run-length encoding – it’s unusual for a RLE of a binary encoding to contain any number higher than 6.

  • There is no digit 1, which is highly unusual for a run-length encoding.

The last observation prompts us to try a different approach replace each letter with a number, but let using the scheme a=0, b=1, etc. We obtain the string 1111113332538111221313121121143141322111131223235213131222211112232121112122221.

There is still the oddity of the digit 8, but the sum of the digits is now equal to 152, which is a multiple of 8. This encourages us to go ahead and decode the run-length cipher to a binary string. The expanded binary string, broken into groups of 8, is: 01010100 01110001 10000011 10000000 01010011 01110111 01101001 01111000 10000100 01100101 01110110 01110011 10000011 01110111 01100110 01010110 01110010 01010010 01100110

This looks promising – note how the groups in the numbers positions (marked in red) all start with 0101. Decoding the above 8-bit binary to ascii doesn’t yield anything interesting, but when using the site http://home.paulschou.net/tools/xlate/ to convert the bit string to hexadecimal, we obtain the string 54 71 83 80 53 77 69 78 84 65 76 73 83 77 66 56 72 52 66. Note how all these numbers fall inside the decimal range (50-57 for numbers, 65-90 for uppercase letters)

 Decoding these numbers from decimal to ascii, we obtain 6GSP5MENTALISMB8H4B, which is a valid passcode.

Passcode solution:

Replace each letter with a number (b=1, c=2, etc), and consider the string of numbers so obtained as a run-length encoding of a bit string. The decoded bit string is 01010100 01110001 10000011 10000000 01010011 01110111 01101001 01111000 10000100 01100101 01110110 01110011 10000011 01110111 01100110 01010110 01110010 01010010 01100110, which deocdes from binary to hex as 54 71 83 80 53 77 69 78 84 65 76 73 83 77 66 56 72 52 66, which in turn decodes from decimal to ascii as the passcode

6GSP5MENTALISMB8H4B

Passcode items gained:

400 AP

400 XM

L8 Resonator (1)

L1 XMP Burster (2)

Portal Shield (1) (Common)

L4 Power Cube (1)

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1 Comment

  1. I’m a little lost on this one. 1st problem: 231 is, in fact, a multiple of 7, so perhaps 7-bit binary encoding should have been explored with the a=1 string. 2nd problem: I can’t figure out how you “decode the run-length cipher to a binary string” with the a=0 string; do you have a tool in your toolbox for this that you could share with us? I tried https://www.dcode.fr/rle-compression, but didn’t arrive at anything like the binary string you showed. Thanks for your walk-throughs; I’m learning a lot!

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Passcode Decoding Walkthrough #003.2

by DI Decoder time to read: 2 min
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