201209271100 10kzwe

explained decrypted filler

3DES(name+title) ECB, 8 GUIDs, seed 527

Metadata

Post ID: 10kzwe
Title: 201209271100 → 2012-09-27 11:00 on A858's clock
Posted (UTC): 2012-09-27 21:00:02
Timezone: UTC−10 · title 11:00 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: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209271100) = 3c0da8f674355aec1eb03ca69e362ec0 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 8
Filler GUID seed: new Random(527).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 267 · predicted N = 8 ✓
Machine boot: 2012-09-22 10:23–10:24 (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: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209271100 (name+title). Key = MD5(password) = 3c0da8f674355aec1eb03ca69e362ec0, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 b8b612dc-0725-006b-9b95-5a05a61c779e
  2 73bd306e-8792-46e9-9e10-8e1cf3812b4a
  3 1540cc4b-d593-18fd-a428-d9b6099a7262
  4 c539229d-5d82-099c-aea8-0ad5fb601515
  5 3e3d9245-fa8e-1ac8-b14c-5278a4adefef
  6 a2d395e1-a6c4-0185-955c-142eca01e911
  7 9fa56b14-7ee3-0b7b-94ca-366101e1a341
  8 db0a05bb-3b29-708c-ab1d-b165f0258a7e

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 04101007. Exactly this sequence comes out of new Random(527).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 267 of Run 34 (seed 83,105,000): new Random(83105000), Next(8,64) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:23–10:24).
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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