201308310400 1lfmdo

explained decrypted filler

seed 12

Metadata

Post ID: 1lfmdo
Title: 201308310400 → 2013-08-31 04:00 on A858's clock
Posted (UTC): 2013-08-31 00:00:00
Timezone: UTC+4 · title 04:00 against posted 00:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,296 hex characters · 648 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201308310400) = af4b81cdc8cc364b0b47d1abab837670 (name+title)
GUIDs: 20
Filler GUID seed: new Random(12).Next(9) ✓ verified
Run: Run 52 (seed 1,430,705,843) (seed)
Draw: 1 · predicted N = 20 ✓
Machine boot: 2013-08-14 07:34–10:34 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 5 · 0
Tags: automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 1,296 hex characters = 648 bytes = 81 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201308310400 (name+title). Key = MD5(password) = af4b81cdc8cc364b0b47d1abab837670, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 20 GUIDs as hex (shown below).

Decrypted: GUID list

  1 7e2fffd4-7af8-8c3a-877f-9a7429768c18
  2 e0cef8ca-4e04-3ded-a61b-3d5053fe21f1
  3 fed603da-7936-1e08-9333-48a60a0d8e40
  4 334093f6-cb7f-1b43-8425-81d55cd7b9db
  5 fbb26a9c-73ed-5751-8526-d18ff2255c54
  6 effaf63c-6939-0029-8248-0bcd4be78137
  7 34f82bc5-1c55-27a0-b5a2-a88f588a52a8
  8 dc903791-a555-42aa-8213-2b9f4fedc4ec
  9 6ba03a35-dafe-4445-aa36-ff2158b3b3d3
 10 a902ba58-2d82-6f22-95d4-bb57d885b079
 11 c92c5303-2215-1802-9f29-4c3b8de8f6e3
 12 8ee92f82-0864-76f2-b0de-98652f41f3c9
 13 d0010002-23ba-705a-8c7c-5d206741e845
 14 967881fb-fccd-6a3f-a3a0-0cf14a2ff145
 15 eae6ba6d-c899-3d28-8a82-50f43ee0dd49
 16 30bf1e50-e714-4dd8-abe5-d043c23494e6
 17 f74ceba7-8b3e-8d27-9bb4-c34d1684d413
 18 6ee34fc6-ac6d-31f6-8f71-9c6b8e2f122c
 19 550f5008-3bb0-00c3-956a-654cf69c2cd6
 20 515abfe3-8915-80c4-a18b-7eeb6648eccb

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 83115024461776348308. Exactly this sequence comes out of new Random(12).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 1 of Run 52 (seed 1,430,705,843): new Random(1430705843), 4·Next(1,12) per post. The RNG predicts N = 20; the post has N = 20 ✓. The seed is the machine's uptime in ms when the app started (boot 2013-08-14 07:34–10:34).
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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