201212071000 14f49g

explained decrypted filler

seed 384

Metadata

Post ID: 14f49g
Title: 201212071000 → 2012-12-07 10:00 on A858's clock
Posted (UTC): 2012-12-07 02:00:23
Timezone: UTC+8 · title 10:00 against posted 02:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 720 hex characters · 360 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201212071000) = 86fbbe106f56d5c619f3d0420d31ccb7 (name+title)
GUIDs: 11
Filler GUID seed: new Random(384).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 75 · predicted N = 11 ✓
Machine boot: 2012-11-20 22:02–00:02 (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: 720 hex characters = 360 bytes = 45 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201212071000 (name+title). Key = MD5(password) = 86fbbe106f56d5c619f3d0420d31ccb7, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 11 GUIDs as hex (shown below).

Decrypted: GUID list

  1 dd9f748d-65e9-3bdf-ad55-1c69e3434069
  2 15ec13ee-964a-4a6d-8da3-e2a4b1790417
  3 561971db-7c7c-182e-8e63-b243f1c41d6a
  4 2714af85-e4da-47c2-b680-255707410897
  5 05c24a82-5cb0-55a3-b0bd-70f01f04fc30
  6 d6c4ec0d-2fd3-1885-9514-b10f5cb2bd9b
  7 01d92b04-426d-8557-93ef-45fc4a1f2b31
  8 4172bc33-5ece-058a-8a66-ee5560830a9e
  9 5bcbdfc2-95cb-41d8-beaf-a4741b811b81
 10 451ba539-f3a8-7ff2-b7f8-ab56dd4b0440
 11 6d4ef9f1-c49e-1ee6-be7d-af981976d4c8

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 34145180471. Exactly this sequence comes out of new Random(384).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 75 of Run 39 (seed 1,106,402,812): new Random(1106402812), Next(8,64) per post. The RNG predicts N = 11; the post has N = 11 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-11-20 22:02–00:02).
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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