201211081515 12ui9p

explained decrypted filler

seed 957

Metadata

Post ID: 12ui9p
Title: 201211081515 → 2012-11-08 15:15 on A858's clock
Posted (UTC): 2012-11-08 07:15:08
Timezone: UTC+8 · title 15:15 against posted 07:15 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 912 hex characters · 456 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201211081515) = f8f21db6f6c3e93de61b1265e401f488 (name+title)
GUIDs: 14
Filler GUID seed: new Random(957).Next(9) ✓ verified
Run: Run 38 (seed 1,045,884,937) (seed)
Draw: 89 · predicted N = 14 ✓
Machine boot: 2012-10-11 03:41–03:51 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 4 · 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: 912 hex characters = 456 bytes = 57 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201211081515 (name+title). Key = MD5(password) = f8f21db6f6c3e93de61b1265e401f488, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 14 GUIDs as hex (shown below).

Decrypted: GUID list

  1 5e0ed1a4-69c6-60b9-b0c4-95f997c4d31b
  2 0228df3e-b2f9-5885-bd81-0769090061c1
  3 244eaa7e-6de3-610c-a680-c7f0afc04065
  4 50ad277c-ced7-73fa-a707-4c86e9e05370
  5 2a242a6c-a3fa-230b-88e3-9fd965b94415
  6 8ea0cf3f-899d-7c04-8e02-737b0aae3d69
  7 d5f5ba1f-c26c-62bd-90f1-8324f81b820b
  8 44d05191-11b6-40ce-82e0-39e9d9fef8c7
  9 fe4da899-d272-397d-9165-c6cfffae9b05
 10 dbfd7873-d2a7-1347-abfe-1a7c4ce9bae7
 11 f49e70f6-99bf-3037-9b7c-076b696e87b7
 12 89770d58-ff82-51ac-87d5-a53d5ebb4047
 13 d905a94a-c21a-468a-82e7-a266f72812b3
 14 101da994-93fc-3314-8193-c3693bbb8311

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 65672764313543. Exactly this sequence comes out of new Random(957).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 89 of Run 38 (seed 1,045,884,937): new Random(1045884937), Next(8,64) per post. The RNG predicts N = 14; the post has N = 14 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-10-11 03:41–03:51).
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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