201212081300 14i7ep

explained decrypted filler

seed 755

Metadata

Post ID: 14i7ep
Title: 201212081300 → 2012-12-08 13:00 on A858's clock
Posted (UTC): 2012-12-08 18:00:01
Timezone: UTC−5 · title 13:00 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: 1,040 hex characters · 520 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201212081300) = 0cb28b814855df84829ff47096025050 (name+title)
GUIDs: 16
Filler GUID seed: new Random(755).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 89 · predicted N = 16 ✓
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: 16 · 6
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: 1,040 hex characters = 520 bytes = 65 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201212081300 (name+title). Key = MD5(password) = 0cb28b814855df84829ff47096025050, 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 f050a2ca-e129-1d4b-8884-04164f993d2d
  2 bfd0e4f6-4768-323d-a6f1-ad1f9a17070c
  3 fe120b27-6054-4716-a80c-136eaf13ef02
  4 b0f4a956-86a2-67ce-925d-3da96472477d
  5 deb1d849-1a77-06a3-b496-2b755f3336d1
  6 d7bd4924-0879-3759-a047-7afc42e21c63
  7 c9ab458c-7448-17c5-9824-826696665582
  8 75572fee-4d85-1caa-886f-c039217d89a0
  9 d687ab57-d4f4-3e03-8d0d-f9fa989db9f9
 10 c1a7f911-07b4-6ab4-a80a-60cbaa7f97f1
 11 1b186cf7-a357-432d-b936-9e676e9eb73d
 12 f3961255-f78b-89bd-870b-43b3364cfbed
 13 d3d4bb1e-48f0-54bf-b0ee-972c08df4374
 14 50abe467-8ce1-2b6b-96b1-5c85a3f53df4
 15 02da7c69-3d14-454d-91a3-7aac23364918
 16 79a24cc9-01c2-4437-8649-98f962a4f64d

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 1346031136485244. Exactly this sequence comes out of new Random(755).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 89 of Run 39 (seed 1,106,402,812): new Random(1106402812), 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 2012-11-20 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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