201208170342 yc0j0

explained decrypted filler

3DES(name+title) ECB, 11 GUIDs, seed 874

Metadata

Post ID: yc0j0
Title: 201208170342 → 2012-08-17 03:42 on A858's clock
Posted (UTC): 2012-08-16 18:42:14
Timezone: UTC+9 · title 03:42 against posted 18:42 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 720 hex characters · 360 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201208170342) = 0b80997cd51773227512e5bc537c7932 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 11
Filler GUID seed: new Random(874).Next(9) ✓ verified
Run: Run 24 (seed 39,416,093) (seed)
Draw: 16 · predicted N = 11 ✓
Machine boot: 2012-08-15 10:18–10:21 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 720 hex characters = 360 bytes = 45 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201208170342 (name+title). Key = MD5(password) = 0b80997cd51773227512e5bc537c7932, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 11 GUIDs as hex (shown below).

Decrypted: GUID list

  1 0fde6f31-7b4e-28e5-b777-6afb9bd1fa07
  2 e2a74c2d-63d5-2d40-9f3b-5a09abd7db0e
  3 e0d383eb-a488-6570-b5a6-b8323687389b
  4 e5195dac-15b2-0d17-8261-050a4b3e4efe
  5 ef4fda67-aed8-7e55-a5e3-1a1f4f9fc320
  6 b56860e9-10cc-3420-92eb-512af958d564
  7 271e6d23-184d-471d-b280-b47c25979fff
  8 97e70f6b-74a2-825b-a093-e223fa2d5535
  9 4f8f2eee-c7c8-0047-b38d-ffd79752b318
 10 1d9defa6-a66d-520d-9cad-ebf95cbda62f
 11 65e19e37-f694-1e1a-90ea-3777fdd1e193

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 22607348051. Exactly this sequence comes out of new Random(874).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 16 of Run 24 (seed 39,416,093): new Random(39416093), Next(8,64) per post. The RNG predicts N = 11; the post has N = 11 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-08-15 10:18–10:21).
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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