201308311259 1lgcfu

explained decrypted filler

seed 587

Metadata

Post ID: 1lgcfu
Title: 201308311259 → 2013-08-31 12:59 on A858's clock
Posted (UTC): 2013-08-31 09:00:00
Timezone: UTC+4 · title 12:59 against posted 09:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201308311259) = e93b0e495db8bdeca80b1b77f800bba0 (name+title)
GUIDs: 8
Filler GUID seed: new Random(587).Next(9) ✓ verified
Run: Run 52 (seed 1,430,705,843) (seed)
Draw: 4 · 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: 0 · 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 = A858DE45F56D9BC9201308311259 (name+title). Key = MD5(password) = e93b0e495db8bdeca80b1b77f800bba0, 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 1dcba330-b0d5-3f39-8dae-7ab7641259da
  2 ce2ca00c-bdbc-0895-a19d-ca4d823dc55a
  3 33482977-3480-06cc-89e9-0a9f452cce09
  4 d7d7a84b-45fa-7942-a0ea-1ac09f2b0e98
  5 77134c15-bb48-2c6e-8f2f-c65beba19d18
  6 d743fcdc-1221-4b92-9c55-3ce632ae3668
  7 cd8aa52d-af7e-821f-a7f1-968b13a49dc7
  8 16fef566-7eb8-8bd5-8448-8563ea084d08

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 30072488. Exactly this sequence comes out of new Random(587).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 4 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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