201208310116 z4dn4

explained decrypted filler

3DES(name+title) ECB, 10 GUIDs, seed 510

Metadata

Post ID: z4dn4
Title: 201208310116 → 2012-08-31 01:16 on A858's clock
Posted (UTC): 2012-08-31 05:16:03
Timezone: UTC−4 · title 01:16 against posted 05:16 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 656 hex characters · 328 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201208310116) = b8eacd89f27e5e2843f0ae844e2ca219 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 10
Filler GUID seed: new Random(510).Next(9) ✓ verified
Run: Run 27 (seed 1,337,299,625) (seed)
Draw: 8 · predicted N = 10 ✓
Machine boot: 2012-08-15 10:07–10:24 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 656 hex characters = 328 bytes = 41 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201208310116 (name+title). Key = MD5(password) = b8eacd89f27e5e2843f0ae844e2ca219, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 10 GUIDs as hex (shown below).

Decrypted: GUID list

  1 3bd2689f-7d6c-1c7c-9915-eb95e49c80ed
  2 acd6075d-7cc8-489a-9e12-d1a413546010
  3 ef48dfae-e596-2d1c-804a-451391076237
  4 62710bae-e1e9-3898-a5ba-ba3997cc44ac
  5 1e2b0c35-8867-4eec-9146-536efe628b7f
  6 716fd0c3-f0bd-2a74-bbd1-46a79521df38
  7 c1c8fff4-188e-311c-928c-c9ddf5305bf5
  8 6d9b75bf-5645-247d-9f93-b3bbc480dd45
  9 e7e74306-ebfd-0c59-81c3-4ec1b8e6301f
 10 fae57919-a892-3918-9df3-d547b480b7ef

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 1423423203. Exactly this sequence comes out of new Random(510).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 8 of Run 27 (seed 1,337,299,625): new Random(1337299625), Next(8,64) per post. The RNG predicts N = 10; the post has N = 10 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-08-15 10:07–10:24).
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