201210022300 10usn2

explained decrypted filler

3DES(name+title) ECB, 16 GUIDs, seed 545

Metadata

Post ID: 10usn2
Title: 201210022300 → 2012-10-02 23:00 on A858's clock
Posted (UTC): 2012-10-03 03:00:55
Timezone: UTC−4 · title 23:00 against posted 03:00 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(A858DE45F56D9BC9201210022300) = 41c9033ec49618932b46cfd5265c5159 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 16
Filler GUID seed: new Random(545).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 57 · predicted N = 16 ✓
Machine boot: 2012-09-22 10:16–10:36 (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 = A858DE45F56D9BC9201210022300 (name+title). Key = MD5(password) = 41c9033ec49618932b46cfd5265c5159, 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 7b4adda1-b2bb-49c7-a8a0-ab3365d548f7
  2 b6000a8c-6b01-675d-b5b5-8c96a4ace24d
  3 05db3c56-f597-6e9a-8874-69b8177d3da5
  4 66c226da-f6cd-726f-8c2b-f38a176fa1c0
  5 8b81593f-269d-2c6a-8433-0f765b29076a
  6 df0d0303-dbbb-7615-ab4e-7e5ae1d7b2ab
  7 125a101a-05ea-09b5-9ee4-ca84ef671cf0
  8 452aea12-8e2d-715a-b81c-75a68f44bba4
  9 3a1b7597-b3c7-31c6-8923-c185fca020cb
 10 3e3948ba-977d-2feb-a85d-c95978dd7f61
 11 59773849-a5d8-7ec5-9d3a-6b896845a69e
 12 707bede4-316b-813e-9f79-08965bf905ad
 13 2fd35fc9-52f7-2225-8192-7226d9dc69a5
 14 7bcfbf36-1e39-04eb-9749-8560151c59df
 15 f1bee9b6-7a51-47e6-b624-2b673067c924
 16 12a696d3-6c62-317b-899a-c0da4ca73b45

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 4667270732782043. Exactly this sequence comes out of new Random(545).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 57 of Run 35 (seed 854,622,578): new Random(854622578), 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 10:16–10:36).
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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