201208170646 yccbv

explained decrypted filler

3DES(name+title) ECB, 16 GUIDs, seed 178

Metadata

Post ID: yccbv
Title: 201208170646 → 2012-08-17 06:46 on A858's clock
Posted (UTC): 2012-08-16 21:46:57
Timezone: UTC+9 · title 06:46 against posted 21:46 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(A858DE45F56D9BC9201208170646) = 497068c7e0f408104de40b1d90339dfc (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 16
Filler GUID seed: new Random(178).Next(9) ✓ verified
Run: Run 24 (seed 39,416,093) (seed)
Draw: 77 · predicted N = 16 ✓
Machine boot: 2012-08-15 10:18–10:21 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 0 · 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 = A858DE45F56D9BC9201208170646 (name+title). Key = MD5(password) = 497068c7e0f408104de40b1d90339dfc, 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 6763573c-99bb-617c-b9b1-bcce8ffb7470
  2 a0203346-5520-0d7f-983e-7ad474e08458
  3 3e9c9209-0bd2-1c55-9b13-21b5153bdb0c
  4 e54257ae-b18e-4837-a35c-5ae6c86b706d
  5 f20d6127-5adc-5074-a217-830bc7b853d6
  6 db4e0a91-f86f-1a0a-a688-2a6a41b45a88
  7 175bdd1c-79f2-5f91-ab5d-ee9ebe0048e3
  8 525f5b0c-a850-690f-a0f6-02d725f88e24
  9 77599e8c-6589-8e2c-8217-fc41f55c821c
 10 637fcc01-8168-8621-9ec0-7a91209a9cfa
 11 c85212b1-4486-3e43-bb51-e0d42630175f
 12 fc950dfd-9441-34c0-8ba5-dcf1d5f86419
 13 60a91ee8-d6fe-8676-a8ec-a27cc19e721c
 14 ae4970fa-e1c6-0e63-a274-9e419d8efa78
 15 ec093343-059b-5ea3-adcb-67e20b7162d8
 16 6bad0eb5-f47a-145f-a949-dd3141a9c4ed

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 6014515688338051. Exactly this sequence comes out of new Random(178).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 77 of Run 24 (seed 39,416,093): new Random(39416093), 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 2012-08-15 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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