201209231429 10cn7w

explained decrypted filler

3DES(name+title) ECB, 15 GUIDs, seed 837

Metadata

Post ID: 10cn7w
Title: 201209231429 → 2012-09-23 14:29 on A858's clock
Posted (UTC): 2012-09-23 18:29:07
Timezone: UTC−4 · title 14:29 against posted 18:29 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 976 hex characters · 488 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209231429) = 810d80dbaa895f7cf976b2a3fd199a02 (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 15
Filler GUID seed: new Random(837).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 106 · predicted N = 15 ✓
Machine boot: 2012-09-22 10:23–10:24 (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: 976 hex characters = 488 bytes = 61 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209231429 (name+title). Key = MD5(password) = 810d80dbaa895f7cf976b2a3fd199a02, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 15 GUIDs as hex (shown below).

Decrypted: GUID list

  1 85159f6f-e63b-811c-ad43-4493d9b5da8d
  2 8ac302e7-7737-3ece-98b0-a5373d0c23b5
  3 1bf44b7c-c4eb-7734-a295-d424adec03b2
  4 add3d013-a7e5-162c-a155-c2629b89d378
  5 1d6ff19a-f262-0d5a-98be-926a4cf9a9d7
  6 51209733-0bbb-041b-8eb2-260f78514598
  7 510b6f7e-15a1-8dbc-a384-bccbf7364277
  8 18435f9d-de0f-3a84-85c1-d9f40da9f856
  9 2307b2a1-b2c4-4b44-86de-4a6f8af62206
 10 be51848b-4aae-8610-967d-dde10e050eb3
 11 1e81b69f-51fe-8977-9a73-d0ce4c94f2fe
 12 2241ce78-183e-8e81-b2c7-08e13916032d
 13 2d84d83e-c624-0ad5-aaec-62015d5f5fea
 14 035681fc-67c8-8fc8-ab21-d22be1fa8cef
 15 e846b754-0dbb-7528-a9d1-2a3d3cac7673

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 837100834888087. Exactly this sequence comes out of new Random(837).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 106 of Run 34 (seed 83,105,000): new Random(83105000), Next(8,64) per post. The RNG predicts N = 15; the post has N = 15 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:23–10:24).
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

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