201309051559 1ls1ux

explained decrypted filler

seed 316

Metadata

Post ID: 1ls1ux
Title: 201309051559 → 2013-09-05 15:59 on A858's clock
Posted (UTC): 2013-09-05 11:59:53
Timezone: UTC+4 · title 15:59 against posted 11:59 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(A858DE45F56D9BC9201309051559) = d9a0019f41c0028a89dc0f84500b05c5 (name+title)
GUIDs: 8
Filler GUID seed: new Random(316).Next(9) ✓ verified
Run: Run 52 (seed 1,430,705,843) (seed)
Draw: 45 · predicted N = 8 ✓
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: 6 · 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: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309051559 (name+title). Key = MD5(password) = d9a0019f41c0028a89dc0f84500b05c5, 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 9a0f15c8-9cae-76a0-af0f-6b9cd80d6603
  2 17cdf2da-bb5a-481e-9115-f5cb98db85ca
  3 c71bb2d2-3d40-52e8-839f-9d45f0a72144
  4 1eac51dc-4921-031d-b078-b879c186268e
  5 d5e90674-24ea-75a3-9755-455010aa854e
  6 5bdff6ec-79d7-65dd-9b6d-75a1e8f108b8
  7 8fef031c-84c7-438d-bee2-5a40d2c12722
  8 a18623a0-014c-82c9-8b2c-5a0ae735e7bb

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 74507648. Exactly this sequence comes out of new Random(316).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 45 of Run 52 (seed 1,430,705,843): new Random(1430705843), 4·Next(1,12) 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 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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