201309161259 1mieyz

explained decrypted filler

seed 997

Metadata

Post ID: 1mieyz
Title: 201309161259 → 2013-09-16 12:59 on A858's clock
Posted (UTC): 2013-09-16 16:59:55
Timezone: UTC−4 · title 12:59 against posted 16:59 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 784 hex characters · 392 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201309161259) = 62d1c0c1055698f656dbeebcf28cfbda (name+title)
GUIDs: 12
Filler GUID seed: new Random(997).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 96 · predicted N = 12 ✓
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: 7 · 1
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: 784 hex characters = 392 bytes = 49 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309161259 (name+title). Key = MD5(password) = 62d1c0c1055698f656dbeebcf28cfbda, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 12 GUIDs as hex (shown below).

Decrypted: GUID list

  1 b8ee5e00-5cc8-5390-a3a6-f9166603d845
  2 e4a184c9-9a66-33ac-84fc-c999d2ebb7f9
  3 a5f6c864-a995-5e5f-912e-49e18e856749
  4 83203bcb-2fed-38c7-a908-2c1725c2287f
  5 3d0f0e71-c3a2-3b8c-a370-352639323f37
  6 0b71877b-1a0e-73f9-8fe1-f81849479d24
  7 263eac1a-1351-5a5e-9a6d-d78a0140fe6d
  8 3c541eaa-d9d6-54ac-b53e-a4e2d7ef46b4
  9 d130326a-ee9a-2090-9e1b-4b808e790f8c
 10 af26deca-4868-8568-b2e5-6f27cfe5b9e8
 11 64c845c8-1d84-77b7-aa49-04b5162d718c
 12 9847b883-7e33-7861-ae00-4583666c9c9e

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 535337552877. Exactly this sequence comes out of new Random(997).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 96 of Run 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) per post. The RNG predicts N = 12; the post has N = 12 ✓. 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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