201210110200 119d9l

explained decrypted filler

seed 296

Metadata

Post ID: 119d9l
Title: 201210110200 → 2012-10-11 02:00 on A858's clock
Posted (UTC): 2012-10-10 17:00:35
Timezone: UTC+9 · title 02:00 against posted 17:00 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(A858DE45F56D9BC9201210110200) = 2cb9d7cdd12b273e777fe9c96e8aadca (name+title)
GUIDs: 8
Filler GUID seed: new Random(296).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 531 · predicted N = 8 ✓
Machine boot: 2012-09-22 10:16–10:36 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 7 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210110200 (name+title). Key = MD5(password) = 2cb9d7cdd12b273e777fe9c96e8aadca, 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 937162d2-3ae8-3177-8031-2958790bf645
  2 28f35823-ae23-6702-a0c0-5f58e37ad428
  3 137b2e07-50e1-6165-b1de-0564315644b0
  4 a667d870-bbc7-6596-a2bf-c9c8edff23df
  5 bba0b524-9686-7816-8b69-a5dc0989c201
  6 cf45226c-a15a-2d2b-bb96-06f57286ef84
  7 0ac812a8-b038-4b35-a2be-b150dae6bfbe
  8 943225c5-b15a-8e42-818d-c09919cfa354

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 36667248. Exactly this sequence comes out of new Random(296).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 531 of Run 35 (seed 854,622,578): new Random(854622578), 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 2012-09-22 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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