201209070530 zhoij

explained decrypted filler

seed 283

Metadata

Post ID: zhoij
Title: 201209070530 → 2012-09-07 05:30 on A858's clock
Posted (UTC): 2012-09-07 04:30:15
Timezone: UTC+1 · title 05:30 against posted 04:30 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209070530) = f432a6fb025741a9c39c008866137cbb (name+title)
GUIDs: 8
Filler GUID seed: new Random(283).Next(9) ✓ verified
Run: Run 30 (seed 1,932,335,625) (seed)
Draw: 9 · predicted N = 8 ✓
Machine boot: 2012-08-15 09:44–10:44 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 10 · 1
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

677EDDDC85D48430 BC13CD77C5132CC8 0281D7FFCA2B55E3 4EAD9DC9F50680D7 511669A1C6797A86 83E051989177BCC8 E6851894747D47A7 28CFDB57B0DE48D3 6CD127AEDE05C5D0 0A785C173DD8C1FC CBA09883A81A45AA 908A9CFEE8700B11 97D1D017666915BF 4C0F677175279F09 BAC7A197EFAF89EC 04BE4B68CF1257FA A08F7254095C5657 361EDE08671A8868 C37A13EE0CD1F872 257CEDAC31D5FBAF 14443502DB611155 D2034769C25B3C3A 4D5E07B8F8A9C1B2 4AEE4656EF768D37 87C326C3C87E2B41 81AD5EE625F61C6A BF99F8B03A94E57F 189023A02E7DD4C0 72DA29D16B4474B6 4B2A2A08DE82C053 4D218E9100A22D49 BDF153B626FC7C86 CC2003118F34E4DF

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209070530 (name+title). Key = MD5(password) = f432a6fb025741a9c39c008866137cbb, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 7af6f17c-dcd0-59ab-a98c-5f68a6565697
  2 a3e4d611-51b0-7461-8300-e96104e8aa02
  3 a5c6c6d1-2774-54c1-a700-fa24d0d191b7
  4 937bb9e0-e9f6-8774-bfdb-58ec6ecb5d51
  5 f5be7e6a-24c6-8465-938f-088dcb12e7e1
  6 0596ebcf-eb96-7cca-b2ed-66ab5684ce7a
  7 559548c6-d887-6008-b05a-f9ce3a9a3a1b
  8 ee474221-605a-3104-8bbf-86d78cf79bda

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 57588763. Exactly this sequence comes out of new Random(283).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 9 of Run 30 (seed 1,932,335,625): new Random(1932335625), Next(8,64) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-08-15 09:44–10:44).
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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