201207100922 wbqw4

explained decrypted filler

seed 235

Metadata

Post ID: wbqw4
Title: 201207100922 → 2012-07-10 09:22 on A858's clock
Posted (UTC): 2012-07-10 13:20:12
Timezone: UTC−4 · title 09:22 against posted 13:20 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(A858DE45F56D9BC9A858DE45F56D9BC9) = 0dcc4bd9e114ebc42078977dc9125404 (name+name)
GUIDs: 9
Filler GUID seed: new Random(235).Next(9) ✓ verified
Run: Run 14 (seed 205,976,312) (seed)
Draw: 18 · predicted N = 9 ✓
Machine boot: 2012-07-05 08:28–12:28 (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+namerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9A858DE45F56D9BC9 (name+name). Key = MD5(password) = 0dcc4bd9e114ebc42078977dc9125404, 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 33343f81-5e9d-462a-aa38-8df1441abef8
  2 5ffccae6-22fd-68a9-af5a-e7e4a27bd1b4
  3 14f81c4c-5054-06ba-b4ae-cbca8e18a91f
  4 7af8a5a2-23dd-60d3-aee1-cd03734cc23e
  5 bbc9d0d7-1d0e-294b-9aaf-898123c333ec
  6 313e712b-872b-8b81-bfae-715fbc9de4cd
  7 8cc3c574-605e-10cb-bded-b46559e2c3ba
  8 ec4176c4-83a6-33f1-ad99-a549a6984eda
  9 fcee2449-1256-03f7-b898-d55bb250ebe7

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 460628130. Exactly this sequence comes out of new Random(235).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 14 (seed 205,976,312): new Random(205976312), 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 2012-07-05 08:28–12:28).
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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