201208170243 yd6d1

explained decrypted filler

seed 462

Metadata

Post ID: yd6d1
Title: 201208170243 → 2012-08-17 02:43 on A858's clock
Posted (UTC): 2012-08-17 06:43:26
Timezone: UTC−4 · title 02:43 against posted 06:43 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,040 hex characters · 520 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201208170243) = 89f72e5a43c5c0d61d6e1e468dcd2397 (name+title)
GUIDs: 16
Filler GUID seed: new Random(462).Next(9) ✓ verified
Run: Run 25 (seed 158,297,437) (seed)
Draw: 2 · predicted N = 16 ✓
Machine boot: 2012-08-15 10:14–10:24 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 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: 1,040 hex characters = 520 bytes = 65 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201208170243 (name+title). Key = MD5(password) = 89f72e5a43c5c0d61d6e1e468dcd2397, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 16 GUIDs as hex (shown below).

Decrypted: GUID list

  1 2888e59f-962a-00ca-a14c-2600bbc1fdac
  2 080aea72-dc6d-32be-ad40-7db741e8a067
  3 309727c9-f900-6277-ac9e-47810a2c9529
  4 fc1e7527-dad4-1548-b8c0-c62392c0fcbd
  5 b0c6bc4f-16c2-7e4f-8c26-0b267b74e0ac
  6 7cd889f8-0e75-24eb-a665-1987dfbd419f
  7 b43a6d3b-4a18-8344-8c75-eaf3bb70ff4a
  8 751bda17-710d-1a5e-83f9-cd4d3391597c
  9 99272c85-4c74-1f11-8ca0-fa82852327a6
 10 7d5de06a-ccc0-5b02-bf7c-f983566aca03
 11 be3fa030-69fe-5364-b3d0-1906413e1e6c
 12 f7bf256d-d727-1851-b190-e3418119e113
 13 6c55b476-d5bd-2c88-b58e-af809bd78f1a
 14 b0d26631-390e-7cae-a3dd-324ab54e6b2b
 15 ab4653db-bfd1-3094-99ea-a13eebecffa8
 16 23d9fb0d-2b62-56b0-8b53-ee4f5cc3242e

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 0361728115512735. Exactly this sequence comes out of new Random(462).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 2 of Run 25 (seed 158,297,437): new Random(158297437), Next(8,64) per post. The RNG predicts N = 16; the post has N = 16 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-08-15 10:14–10:24).
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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