201210141700 11h6no

explained decrypted filler

seed 679

Metadata

Post ID: 11h6no
Title: 201210141700 → 2012-10-14 17:00 on A858's clock
Posted (UTC): 2012-10-14 21:00:21
Timezone: UTC−4 · title 17:00 against posted 21:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 784 hex characters · 392 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201210141700) = 3ea2a22b41bf6c655fcc1ff948258469 (name+title)
GUIDs: 12
Filler GUID seed: new Random(679).Next(9) ✓ verified
Run: Run 36 (seed 335,015) (seed)
Draw: 24 · predicted N = 12 ✓
Machine boot: 2012-10-10 20:54–00:54 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 6 · 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: 784 hex characters = 392 bytes = 49 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210141700 (name+title). Key = MD5(password) = 3ea2a22b41bf6c655fcc1ff948258469, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 12 GUIDs as hex (shown below).

Decrypted: GUID list

  1 e9f5e8b4-ba60-43fd-9f1c-934b59252786
  2 04d078f4-e7be-02e3-abb9-847f6229f0ac
  3 66b953f6-9bd6-3538-b38b-78681a4ccf9a
  4 92b0ac8a-589b-4af5-9397-3f1ab8013924
  5 44ab6c68-ade1-69e0-9bed-3229b6ed0830
  6 a2810850-8503-84b8-aaf0-897b98695f3f
  7 c0ba4d11-bf25-1fa0-b236-4fc40d817c5b
  8 b65bca1b-d92f-0a24-b0d0-74e8789a2c3a
  9 7aa7b082-8619-852f-b871-dd052812f3c4
 10 80f6459c-836c-550f-876a-5ebbe6c4a450
 11 c3b5b523-50fb-4add-822f-b8a02b44d653
 12 27051017-2450-55da-913a-883afb786071

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 403468108545. Exactly this sequence comes out of new Random(679).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 24 of Run 36 (seed 335,015): new Random(335015), Next(8,64) per post. The RNG predicts N = 12; the post has N = 12 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-10-10 20:54–00:54).
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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