201208170732 ycf66

explained decrypted filler

seed 357

Metadata

Post ID: ycf66
Title: 201208170732 → 2012-08-17 07:32 on A858's clock
Posted (UTC): 2012-08-16 22:32:16
Timezone: UTC+9 · title 07:32 against posted 22:32 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,296 hex characters · 648 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201208170732) = 5713af424310cfb146500075ef2967cb (name+title)
GUIDs: 20
Filler GUID seed: new Random(357).Next(9) ✓ verified
Run: Run 24 (seed 39,416,093) (seed)
Draw: 92 · predicted N = 20 ✓
Machine boot: 2012-08-15 10:18–10:21 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 0 · 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: 1,296 hex characters = 648 bytes = 81 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201208170732 (name+title). Key = MD5(password) = 5713af424310cfb146500075ef2967cb, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 20 GUIDs as hex (shown below).

Decrypted: GUID list

  1 f57841c1-5078-224a-8c8a-7d93ba543bd5
  2 4f14c0de-9f40-56f6-954a-f23699fd430e
  3 715f567c-96bf-294f-86af-6e1a72d6ee87
  4 ee55bbbd-c584-650e-bc38-db7960eda39e
  5 0ae17655-4862-3821-987e-d3ccfa0d8b5d
  6 28f81450-6e5f-4872-9ead-a1b517d41b9e
  7 8e97f81e-c7c5-7cd9-857c-1eefe0284fbf
  8 9bd2dda6-1679-49ea-8577-7ffa9d70beaf
  9 9ff1fee0-4ae5-1778-9561-8c3fdcd0be9f
 10 568b78a9-b9f3-869f-b172-76f7b590433c
 11 b49832d1-c96e-2c02-9acd-e9ad433d5985
 12 cc63c66d-ace8-1f9e-9f81-f3960a71b96d
 13 15ad04d8-31d9-08f2-a882-3392e82e1053
 14 14afccd9-d46e-16cb-a57f-7e0f7b681c47
 15 509e4d1a-3125-7b2a-ac89-2dc3e43c3612
 16 978dae57-968a-8574-bbce-75c6164a3b9f
 17 a9fa4d95-6ee2-8be8-9844-96a55d5c02cf
 18 f460bb80-142e-347f-8c74-b7c66c88cf6f
 19 f33d113d-a755-3bb2-ae00-66266042d8b3
 20 00af7e52-aa33-4b5c-a32f-dd08724ebced

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 25263474182101788334. Exactly this sequence comes out of new Random(357).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 92 of Run 24 (seed 39,416,093): new Random(39416093), Next(8,64) per post. The RNG predicts N = 20; the post has N = 20 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-08-15 10:18–10:21).
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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