201209080800 zjwfe

explained decrypted filler

seed 717

Metadata

Post ID: zjwfe
Title: 201209080800 → 2012-09-08 08:00 on A858's clock
Posted (UTC): 2012-09-08 12:00:06
Timezone: UTC−4 · title 08:00 against posted 12:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 720 hex characters · 360 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209080800) = eafeb9f220633625f7bf9c3e969fa35d (name+title)
GUIDs: 11
Filler GUID seed: new Random(717).Next(9) ✓ verified
Run: Run 31 (seed 15,917,281) (seed)
Draw: 7 · predicted N = 11 ✓
Machine boot: 2012-09-07 23:34–00:34 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 4 · 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: 720 hex characters = 360 bytes = 45 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209080800 (name+title). Key = MD5(password) = eafeb9f220633625f7bf9c3e969fa35d, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 11 GUIDs as hex (shown below).

Decrypted: GUID list

  1 b6073ce0-c0ef-2efc-b1c6-c11678d9d420
  2 58606716-4cb5-1c89-86d5-7bcdb748ce0e
  3 d36af99f-494e-8f2c-a887-91733890c621
  4 83c42eba-f8b4-5c21-8d99-dae785a934a1
  5 5dc32d49-a230-8c79-82c9-4b626c757fde
  6 b250bf80-c753-1060-a835-483a5896be2e
  7 cec55c6b-84c0-1a89-8e78-a405acd43b2c
  8 47b7ba1b-262a-1ae3-af8e-75fa7d7d1046
  9 28114b0d-0f20-6221-b1ca-34b436ebad6a
 10 46b804eb-6b0a-6ce7-bb03-ee76efcc0da0
 11 5b76e44c-8692-4161-a30c-26ac2f13d190

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 21858111664. Exactly this sequence comes out of new Random(717).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 7 of Run 31 (seed 15,917,281): new Random(15917281), Next(8,64) per post. The RNG predicts N = 11; the post has N = 11 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-07 23:34–00:34).
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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