201310071915 1nxzku

explained decrypted filler

seed 865

Metadata

Post ID: 1nxzku
Title: 201310071915 → 2013-10-07 19:15 on A858's clock
Posted (UTC): 2013-10-07 23:15:06
Timezone: UTC−4 · title 19:15 against posted 23:15 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(A858DE45F56D9BC9201310071915) = 1cae9ae0014adf04f4588d1bd49d0163 (name+title)
GUIDs: 12
Filler GUID seed: new Random(865).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 160 · predicted N = 12 ✓
Machine boot: 2013-09-12 09:30–10:30 (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)2013Encrypted 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 = A858DE45F56D9BC9201310071915 (name+title). Key = MD5(password) = 1cae9ae0014adf04f4588d1bd49d0163, 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 d5c8c2b7-50b6-5467-85d5-2a0f71869575
  2 2e862d08-c336-5b97-9afb-148a72ff7aa1
  3 260c9625-ac87-3488-acad-74e5bea47ef4
  4 e1b48575-cdd3-1bbc-a2e7-72acf9193ad7
  5 a90af568-1747-6e68-9d59-2992233769c6
  6 2e61643d-568e-487d-8735-76905acaa6e9
  7 3b2a4e82-ec02-4f99-8f73-8f14668ec97d
  8 b9cfd2cd-d463-3d5e-916c-0992e663e514
  9 c0ed4fba-8772-8931-900b-a3343f1115a9
 10 9d76aaaa-d8e4-221a-9a8e-b83de9b39e28
 11 85c7066c-9c6b-5789-8f3b-babcb5022529
 12 c492aa6a-6fe1-7fce-b87f-e5545b38a868

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 553164438257. Exactly this sequence comes out of new Random(865).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 160 of Run 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) 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 2013-09-12 09:30–10:30).
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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