201210220600 11uzly

explained decrypted filler

seed 547

Metadata

Post ID: 11uzly
Title: 201210220600 → 2012-10-22 06:00 on A858's clock
Posted (UTC): 2012-10-21 21:00:07
Timezone: UTC+9 · title 06:00 against posted 21:00 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(A858DE45F56D9BC9201210220600) = 1d80d2c1cc45e765a9dd82eb8f7b2f21 (name+title)
GUIDs: 9
Filler GUID seed: new Random(547).Next(9) ✓ verified
Run: Run 37 (seed 425,468,968) (seed)
Draw: 18 · predicted N = 9 ✓
Machine boot: 2012-10-10 14:48–22:48 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 13 · 1
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

6E006168A52946AD 5F0EA4CA63A26874 3ED59788A485F08B 5E23AE120E13B3AB 444351E226CB1A31 F67EA138780FDB13 7AF9CE65D6E4E380 7DC21833CE9B47CC 0398C82E889738B1 4A396E5D4470D2B2 E1D5640CD9F0C876 255F37C9C9A3D49B 60D033B3B43C8399 875806A82F1BA437 6D53C4FB03457FE3 EA6E722A334EE10A 590AA07AB279CEF6 928BB460759EB1B5 DF74610A928E5836 B5C4D71741D2F246 7255FB3FEE449419 4752C9654420C44F 199588F10FED6F23 EADAF46C04654EC9 9A0C53EFED6CB935 FC4070F9511DE064 0F485E525D1D9423 A81E449B114FABDB F3A0E396611909E3 769B891BE195C04C FCDB92EB9795D039 2CEA00B65EF0C25E 72871CB721F277BD D82EDFCF6ABA2F32 65B0EEAB06BE8313 EFC186A7B8A00402 63AF09BBA7DA27A6

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210220600 (name+title). Key = MD5(password) = 1d80d2c1cc45e765a9dd82eb8f7b2f21, 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 dc9c3d34-e720-4f58-a29b-0415946a2491
  2 8a28ded8-70f6-23a5-9511-af02d008c42f
  3 f1a5f580-d7d3-1d03-b109-712ea6278180
  4 85221137-a3f4-2303-9af5-f5bdba8d9b9e
  5 aa7a69be-3ef8-185c-bf8d-fbc0fd25a4b2
  6 fdd93c10-0e8a-56c5-a216-d31d6a6ffc0c
  7 1874e087-4e98-820c-ac99-fb0d0daaec43
  8 4b4c03e5-7a17-7c8e-a51e-57d965ce70be
  9 a35208b6-ec85-55cf-9ed7-982ceb368f23

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 421215875. Exactly this sequence comes out of new Random(547).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 18 of Run 37 (seed 425,468,968): new Random(425468968), 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 2012-10-10 14:48–22:48).
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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