201209232130 10c84j

explained decrypted filler

3DES(name+title) ECB, 21 GUIDs, seed 50

Metadata

Post ID: 10c84j
Title: 201209232130 → 2012-09-23 21:30 on A858's clock
Posted (UTC): 2012-09-23 12:30:08
Timezone: UTC+9 · title 21:30 against posted 12:30 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,360 hex characters · 680 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209232130) = 70db1734ce56cf1be0c1914ad7f47a55 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 21
Filler GUID seed: new Random(50).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 9 · predicted N = 21 ✓
Machine boot: 2012-09-22 10:23–10:24 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 1,360 hex characters = 680 bytes = 85 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209232130 (name+title). Key = MD5(password) = 70db1734ce56cf1be0c1914ad7f47a55, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 21 GUIDs as hex (shown below).

Decrypted: GUID list

  1 27ee09a1-399a-72e6-9afe-207c895eb334
  2 e5ba1fc3-57ab-46c9-a714-28f4ac4e828c
  3 cce4f5a1-a8d6-60bd-a4db-e835c42574ab
  4 2cf02e9d-040d-2468-8d2c-6688ea60d417
  5 02d3430c-bc01-7158-b452-b95c474b047a
  6 ff0d66e2-f638-2504-9d7f-d897d8e471e9
  7 5e27c522-a85f-2ed1-9c86-eb14ba8910c2
  8 c29d17e5-26a8-4dfe-9003-173cc2defe45
  9 7035ca50-6cf2-15fc-8ccb-b79417c03cfc
 10 64a8a42d-054b-6d0f-96bd-47b4aa6e327d
 11 1b2acca0-bea8-105c-b386-2a285e6ee0ac
 12 9a659c5a-f76d-4bf4-a5d1-75ee03d084a6
 13 1972d398-a3ef-0dfe-ad4a-17730516796a
 14 4512bde9-6004-48c5-ac0b-d1a75ce716d7
 15 c70e42e3-f1fc-83c2-9358-3519bebcee38
 16 1500bb4e-b9bc-280a-8e80-ba3e6ad07b31
 17 b2c61f05-1a82-732f-b8e8-823a8bb6ce35
 18 5e47c871-de16-8877-bdce-67738f767048
 19 0e998d6f-58c9-0b3d-92fb-5c495376b928
 20 e1f8d529-096b-6a29-b805-384f0530da22
 21 fef061bf-8794-43de-a388-6fe5d4d1229c

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 746272241614048278064. Exactly this sequence comes out of new Random(50).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 9 of Run 34 (seed 83,105,000): new Random(83105000), Next(8,64) per post. The RNG predicts N = 21; the post has N = 21 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:23–10:24).
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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