201309152259 1mh53n

explained decrypted filler

seed 780

Metadata

Post ID: 1mh53n
Title: 201309152259 → 2013-09-15 22:59 on A858's clock
Posted (UTC): 2013-09-16 02:59:56
Timezone: UTC−4 · title 22:59 against posted 02:59 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(A858DE45F56D9BC9201309152259) = 57506d73b3d3c674524afa6319621e4b (name+title)
GUIDs: 8
Filler GUID seed: new Random(780).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 82 · 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: 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 = A858DE45F56D9BC9201309152259 (name+title). Key = MD5(password) = 57506d73b3d3c674524afa6319621e4b, 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 c6f2cb94-6d91-1723-95a5-84d901455574
  2 0cf74c9e-8ffc-6777-9ceb-ccd6cb66b2b7
  3 19b9b3f7-3e6d-88a8-a2f6-8a479c9c06fc
  4 84295383-42ee-00ec-a965-aead9acf939d
  5 206a6ff8-2fdd-300f-ad45-86955c12c233
  6 076a106b-c8bc-1d1c-b030-f262d8d3fd63
  7 42843aa7-81b5-3bcc-8263-66718e386d4c
  8 b53523c8-3604-6e02-aac1-0e9feea07662

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 16803136. Exactly this sequence comes out of new Random(780).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 82 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

Related