201209240010 10cdbv

explained decrypted filler

3DES(name+title) ECB, 11 GUIDs, seed 551

Metadata

Post ID: 10cdbv
Title: 201209240010 → 2012-09-24 00:10 on A858's clock
Posted (UTC): 2012-09-23 15:10:16
Timezone: UTC+9 · title 00:10 against posted 15:10 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(A858DE45F56D9BC9201209240010) = fe8db66a01b759090fa8ac68286130eb (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 11
Filler GUID seed: new Random(551).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 17 · predicted N = 11 ✓
Machine boot: 2012-09-22 10:23–10:24 (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 = A858DE45F56D9BC9201209240010 (name+title). Key = MD5(password) = fe8db66a01b759090fa8ac68286130eb, 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 9415fca5-4601-5880-bc22-46cd412208a0
  2 41e1f3e5-b3b0-4dae-9020-7d3712a83770
  3 bba65e83-6e94-8910-b560-db02d0954259
  4 c68b8c55-7e4c-1f01-bbd2-5f7d13e5457d
  5 c8752671-4903-8f32-ae3f-60f4d1dfd625
  6 4f1288b6-33ab-0e57-b10c-a306c76bd44a
  7 0fd03dcb-73ea-7601-82f2-7135a84ac9a6
  8 c08a0c5a-ce54-7e47-9492-e9884aaf1661
  9 829b738e-9fe8-11c9-b52f-4e62e19a0184
 10 cf8c9d32-5305-47c4-af41-e2d9ba6fc5df
 11 87b04a57-7f91-2182-8a2c-75799f8dcf7f

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 54818077142. Exactly this sequence comes out of new Random(551).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 17 of Run 34 (seed 83,105,000): new Random(83105000), 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 2012-09-22 10:23–10:24).
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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