201209181430 103azp

explained decrypted filler

seed 31

Metadata

Post ID: 103azp
Title: 201209181430 → 2012-09-18 14:30 on A858's clock
Posted (UTC): 2012-09-18 18:30:00
Timezone: UTC−4 · title 14:30 against posted 18:30 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,360 hex characters · 680 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209181430) = 0bc8f8406d1d237f3dab9fc172e10f5d (name+title)
GUIDs: 21
Filler GUID seed: new Random(31).Next(9) ✓ verified
Run: Run 31 (seed 15,917,281) (seed)
Draw: 25 · predicted N = 21 ✓
Machine boot: 2012-09-07 23:34–00:34 (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: 1,360 hex characters = 680 bytes = 85 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209181430 (name+title). Key = MD5(password) = 0bc8f8406d1d237f3dab9fc172e10f5d, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 21 GUIDs as hex (shown below).

Decrypted: GUID list

  1 4cd87065-edcc-800f-aaf1-7c8debf8839f
  2 7024dfee-8d41-8bb5-af4a-ae61f513a0c4
  3 f736e1e0-58ae-3eae-bad8-569dc7b3a982
  4 4f038b32-7de0-15bd-84f4-61960fd583d2
  5 871bed9a-ac78-1eaa-bfc4-c9e7dab32d9a
  6 41aa09b3-bda9-578f-88d0-af80e01bcc66
  7 c5b399f3-648b-7c45-a27c-5c5b02e60ddc
  8 acf70b6b-9a2a-8396-948c-9bb1979c84c0
  9 95458bff-13d4-7fb7-80f8-5f88b21fde5c
 10 dc93ed72-25f6-610d-bc0b-2b2b931d72c2
 11 af21e0bd-278c-15c7-857a-d9e1eba70c49
 12 8b5cd8c5-f235-6a10-aa43-dd9c64172a75
 13 34ffc11f-25ea-8106-8584-5b1a7c37d671
 14 2982d3de-3647-5592-b1ed-ab6f460c988f
 15 a681aeed-97f7-6c29-a6cb-8db38f4cdb8f
 16 ac81e658-0ea1-3602-9ece-22e92d355312
 17 4028f28f-856d-8178-ae24-0769b63d3a3f
 18 c7dd41bc-9f79-1649-8002-d6ca308c2e70
 19 b91774e8-dfcf-48aa-8807-31dc761d9d96
 20 11093d22-e40a-2ef6-b755-247ffda4060f
 21 efdc8ad5-c4b5-898b-b686-919db78c2376

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 883115787616856381428. Exactly this sequence comes out of new Random(31).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 25 of Run 31 (seed 15,917,281): new Random(15917281), Next(8,64) per post. The RNG predicts N = 21; the post has N = 21 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-07 23:34–00:34).
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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