201212080200 14gcuh

explained decrypted filler

seed 691

Metadata

Post ID: 14gcuh
Title: 201212080200 → 2012-12-08 02:00 on A858's clock
Posted (UTC): 2012-12-07 18:00:29
Timezone: UTC+8 · title 02:00 against posted 18:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201212080200) = fe5703b37120e22a88cfca6f8b0f3e99 (name+title)
GUIDs: 8
Filler GUID seed: new Random(691).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 83 · predicted N = 8 ✓
Machine boot: 2012-11-20 22:02–00:02 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 6 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

5E5A84AE267A95C2 9CA57166B84FF9E8 72DD1DCC9A5C0858 CFB1803A55138228 B397EDB766A2EAE9 E269976521AAD699 6E6CEA23A231E71F 2C4F0D56B5E8D698 A7A3C3C7268D6DAE 5BABF4D326086709 A9142EEE38409E70 EDB5DA6587E89938 F6FAF3E7E8F9D244 8931D29BF15A043B 67143E3A030499F3 B723BA7370301ED1 C768FAFC2C6726F1 CDABC3CBBE886E56 BC768D53998D311A 7D198217D2E86B40 C9FE9B8C97B8E2A4 5B218725F51ED8E9 D419556DA7B78192 29B469D5E7ED233F 684076633AAD08DB 174D76C262D6BD6F 55F38122C33E31C1 39868B48CA43B4B5 F461B1928F9A6DBC 327601D2958776AF CE14B0FDFE49CA28 D5E3BBCFC6C5C7DA 3E3E24294F1AA33A

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201212080200 (name+title). Key = MD5(password) = fe5703b37120e22a88cfca6f8b0f3e99, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 ae10be66-4cfd-6da9-abcf-da84df754673
  2 eda4a07a-a1bb-5530-a56a-85c01d87f238
  3 20a2e52f-f302-689f-8bc4-1ceeb4e59ebe
  4 9011b56d-1414-00f8-aa81-c96462769906
  5 fff21a60-a093-1702-9931-01b2c6106139
  6 e73ae40f-09bf-36c8-9c3e-98091f2b7a18
  7 aee823ea-c2b9-45e8-92cf-776a64356b91
  8 06a771cd-72e4-0c6b-9b7b-f69a18d13c64

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 65601340. Exactly this sequence comes out of new Random(691).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 83 of Run 39 (seed 1,106,402,812): new Random(1106402812), Next(8,64) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-11-20 22:02–00:02).
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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