201309151559 1mg8dw

explained decrypted filler

seed 79

Metadata

Post ID: 1mg8dw
Title: 201309151559 → 2013-09-15 15:59 on A858's clock
Posted (UTC): 2013-09-15 19:59:56
Timezone: UTC−4 · title 15:59 against posted 19:59 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(A858DE45F56D9BC9201309151559) = 2f7a096111e01f3bb17f0bb335704b9b (name+title)
GUIDs: 8
Filler GUID seed: new Random(79).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 75 · predicted N = 8 ✓
Machine boot: 2013-09-12 09:30–10:30 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 11 · 2
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 = A858DE45F56D9BC9201309151559 (name+title). Key = MD5(password) = 2f7a096111e01f3bb17f0bb335704b9b, 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 5a95fc40-750b-8ceb-8e50-0c9df93f2a0a
  2 84a06da7-e9ae-8773-8af9-07c13053a5ff
  3 85a0ae86-9a5d-80fb-8095-a8c1a197b6f1
  4 13b0e18e-9fed-3867-b99d-8e8ef232a2b5
  5 ee9c8993-5037-77d0-9fbd-dfa9cdd29fe0
  6 e43442b3-f80f-564b-a796-a563a416d627
  7 ff56a928-9d5c-2d9b-b442-5ce9881448d8
  8 6b520723-f356-05d6-8306-aa02de8f5e2e

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 88837520. Exactly this sequence comes out of new Random(79).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 75 of Run 53 (seed 26,950,390): new Random(26950390), 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 2013-09-12 09:30–10:30).
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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