201210070504 112yhb

explained decrypted filler

3DES(name+title) ECB, 9 GUIDs, seed 260

Metadata

Post ID: 112yhb
Title: 201210070504 → 2012-10-07 05:04 on A858's clock
Posted (UTC): 2012-10-07 09:04:56
Timezone: UTC−4 · title 05:04 against posted 09:04 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 592 hex characters · 296 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201210070504) = 6ed2c4223278d9169211b78c10a549a5 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 9
Filler GUID seed: new Random(260).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 363 · predicted N = 9 ✓
Machine boot: 2012-09-22 10:16–10:36 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 0 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

184C99C9E9FF2DD7 C49FE71DC3B6BE85 E745F008291A6EFE 9DD3DDF4D8E89BEF 0238B002EBEAE0EB E697D9427B5F3449 CE60DD0AC9B6F508 4A9F27C9548F9528 5538717307AE74F7 7A99C4A5469E0DCA 37918E10C4705BBD 33F497935ED47685 CF21657067F34A53 079278A03AFEC67B 66F28CE88357CCBE AA3EF13CA4A888D7 020963D4E5B9608B 893FEADE1DF8C7BF 77961540848E7E5A 801174C2777E7096 5F7FBCD9F07C66A3 56ADCC50B14C960F B78902B070F745B0 E0BF8E70380326C1 3C35C5D08E1E77CD 02950B592C4574B6 7E513603CE24003E 02AD3091E3A448AD 184FF0FFCC0071EA 5E8DF1AD7840C972 ED50A789B53099FA 8CF528E161EE27DB B14574841BBC48A4 3CF916522A7A42F7 94E1B339E8DD60FC 221A09FD3165F191 7EB73A512A12CBC3

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210070504 (name+title). Key = MD5(password) = 6ed2c4223278d9169211b78c10a549a5, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 9 GUIDs as hex (shown below).

Decrypted: GUID list

  1 7ed7f026-cd05-5be2-99b4-72e677a259ea
  2 490c1936-f06f-0dce-a931-be04eb41eac4
  3 3262198b-8a8d-4d7d-b2c1-3978926907e8
  4 30dae6ca-fc2a-0952-a681-e244ff23ea6e
  5 83a206d9-63a4-5343-934e-e26417c02fb7
  6 d8b3395b-84dd-60be-9b75-0699f31ff292
  7 5de9beda-b704-3b09-b53b-b868654827f1
  8 b569c07f-8275-7a12-a45f-e3650683422a
  9 a846b4c7-2d47-1be3-b5d8-343b78c85fdd

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 504056371. Exactly this sequence comes out of new Random(260).Next(9): the per-post millisecond seed of the mask generator. The other 30 hex digits of each GUID are Guid.NewGuid() output and carry no message.
Explain the count. This post is draw 363 of Run 35 (seed 854,622,578): new Random(854622578), Next(8,64) per post. The RNG predicts N = 9; the post has N = 9 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:16–10:36).
Conclusion. Filler. The content is fully explained by the two RNGs.

Metadata

From the post to its content

As posted (encrypted)

Decrypted: GUID list

Explanation

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