201207031235 vzgt8

explained decrypted filler

seed 343

Metadata

Post ID: vzgt8
Title: 201207031235 → 2012-07-03 12:35 on A858's clock
Posted (UTC): 2012-07-03 16:33:51
Timezone: UTC−4 · title 12:35 against posted 16:33 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 976 hex characters · 488 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9) = 34a14a42e98ff96095af56604e290cae (name)
GUIDs: 15
Filler GUID seed: new Random(343).Next(9) ✓ verified
Run: Run 10 (seed 38,548,093) (seed)
Draw: 19 · predicted N = 15 ✓
Machine boot: 2012-07-02 09:51–10:51 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 7 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: namerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 976 hex characters = 488 bytes = 61 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9 (name). Key = MD5(password) = 34a14a42e98ff96095af56604e290cae, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 15 GUIDs as hex (shown below).

Decrypted: GUID list

  1 6c46d2ef-c9ae-8831-ac58-9d301edc2a09
  2 4c3b3a46-62e3-44e2-8d4f-005f6ea02937
  3 75cc00fc-2e11-44a4-bc30-e908b84d3d96
  4 ae25f131-9595-6e9e-884b-ac5089e03aae
  5 8e2df39d-0c0e-082e-8567-fe0cad50ab41
  6 6ab12f64-0502-2385-a6d4-2a0c6f0d0400
  7 5f398724-e3d2-52bf-9cb4-b7cb762d5ba8
  8 5405df4c-013c-4201-b900-e2f817e7cc64
  9 d9da2952-3d39-3c6f-bfb5-22117379ffeb
 10 6280aa87-6387-65ed-ba7d-88519a4be704
 11 7d860825-7fa0-8e9d-89fa-1dd23699e07f
 12 11b8ce1d-5b4f-24f6-b52e-93b0bd48505c
 13 c000ddb9-3b18-3d60-9fc8-a5d655c9de94
 14 ebde3452-adf7-8e05-b1b6-4129d5576219
 15 dc7293fd-be53-0814-a628-992176fe0eb5

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 844602543682380. Exactly this sequence comes out of new Random(343).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 19 of Run 10 (seed 38,548,093): new Random(38548093), Next(8,64) per post. The RNG predicts N = 15; the post has N = 15 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-07-02 09:51–10:51).
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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