201208120000 y2vet

explained decrypted filler

seed 376

Metadata

Post ID: y2vet
Title: 201208120000 → 2012-08-12 00:00 on A858's clock
Posted (UTC): 2012-08-12 03:57:47
Timezone: UTC−4 · title 00:00 against posted 03:57 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(A858DE45F56D9BC9A858DE45F56D9BC9) = 0dcc4bd9e114ebc42078977dc9125404 (name+name)
GUIDs: 11
Filler GUID seed: new Random(376).Next(9) ✓ verified
Run: Run 22 (seed 528,385,484) (seed)
Draw: 68 · predicted N = 11 ✓
Machine boot: 2012-07-27 19:02–19:13 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 11 · 1
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+namerun: 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 = A858DE45F56D9BC9A858DE45F56D9BC9 (name+name). Key = MD5(password) = 0dcc4bd9e114ebc42078977dc9125404, 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 de9de24d-cbc6-1055-a5a3-eb5bb7dd1a2c
  2 d7f87f8e-9612-1cc7-b90f-02ab322476d5
  3 43535122-a250-55ff-af04-be7af9c80c31
  4 a4373399-2cdc-70d6-b7b8-a77407d010e1
  5 b13594cd-fa45-884f-a7c9-b581f25b05c5
  6 a8247ae1-5734-1144-983b-48f720d810e2
  7 a0bf06a8-82de-3f72-9d6d-f0cc2a28af87
  8 fb4358d7-487e-0c13-9526-98a68739bcf5
  9 81ad3388-888f-4865-b78c-7e19e12dd890
 10 d15fd1cc-ed56-8996-bd8b-d99a1f669dbf
 11 1d9b7325-1a96-2468-8e18-fe9c1ea25c5b

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 11578130482. Exactly this sequence comes out of new Random(376).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 68 of Run 22 (seed 528,385,484): new Random(528385484), 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 2012-07-27 19:02–19:13).
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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