201209231315 10cj7z

explained decrypted filler

3DES(name+title) ECB, 16 GUIDs, seed 197

Metadata

Post ID: 10cj7z
Title: 201209231315 → 2012-09-23 13:15 on A858's clock
Posted (UTC): 2012-09-23 17:15:16
Timezone: UTC−4 · title 13:15 against posted 17:15 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,040 hex characters · 520 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209231315) = c38a30c745e011fc2b167bc9c4c01062 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 16
Filler GUID seed: new Random(197).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 33 · predicted N = 16 ✓
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: 1,040 hex characters = 520 bytes = 65 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209231315 (name+title). Key = MD5(password) = c38a30c745e011fc2b167bc9c4c01062, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 16 GUIDs as hex (shown below).

Decrypted: GUID list

  1 48231f64-fcb4-5b10-9c01-7f3206168617
  2 daeb13e0-4d3c-5e91-929a-f102b2522bc5
  3 35f454fa-5563-486d-9a83-074ca3107a3e
  4 b98c5071-5977-54fb-9caa-d32d040d29d9
  5 2610dfa5-8ae3-14ff-b3a2-d2b51c5be6f5
  6 43aa8c82-7393-6e03-9aeb-cc27b7ce4bd6
  7 22587ff2-2bb1-16fe-aba8-63c17d71e5b9
  8 18b8ceb7-60bb-2753-b53c-a23a05fd3dcd
  9 fce09a4c-d2dc-39e1-bcc5-ae2ab0c64811
 10 88009d2b-f11c-82ca-86b4-9e173e80b82b
 11 7ef70c93-09af-35a9-a95b-ebfbf3e2d09b
 12 86bdc416-5f80-25e2-8b9a-254466902d5a
 13 c28e96cf-16c0-0c25-aa60-de0df3011b5f
 14 1784e476-d77c-8a88-85b7-995a6aa31123
 15 b9a23ff9-3694-72e8-8157-81e4b3dc0c02
 16 fc13ec11-b3e8-09a5-b7c1-be35712b6354

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 5545161238320870. Exactly this sequence comes out of new Random(197).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 33 of Run 34 (seed 83,105,000): new Random(83105000), Next(8,64) per post. The RNG predicts N = 16; the post has N = 16 ✓. 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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