201210121700 11dutf

explained decrypted filler

seed 342

Metadata

Post ID: 11dutf
Title: 201210121700 → 2012-10-12 17:00 on A858's clock
Posted (UTC): 2012-10-12 21:00:13
Timezone: UTC−4 · title 17:00 against posted 21:00 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(A858DE45F56D9BC9201210121700) = ea90669fb106bb707d3b86c60a451dcd (name+title)
GUIDs: 10
Filler GUID seed: new Random(342).Next(9) ✓ verified
Run: Run 36 (seed 335,015) (seed)
Draw: 12 · predicted N = 10 ✓
Machine boot: 2012-10-10 20:54–00:54 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 25 · 28
Tags: automated (decryptable)2012Encrypted masked GUID listkey: 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 = A858DE45F56D9BC9201210121700 (name+title). Key = MD5(password) = ea90669fb106bb707d3b86c60a451dcd, 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 88203c72-84b6-3da2-a34f-572d7a402705
  2 a4b77199-54bb-170e-9406-b1e095e04e40
  3 f8259de9-441c-7da9-b778-f05f33b8ed7f
  4 1efd545e-f56d-5667-a67d-10fe4bbb7130
  5 eb2a624c-e7d3-5abe-a64c-c6c8716e2156
  6 3ef5ceea-10e7-3c82-b619-6554e2fd0f83
  7 9b35a5c1-7805-16da-9a57-bbd3092d8520
  8 6fc2224c-77d6-06ae-b94f-293972e5f91b
  9 c4198e60-01be-2bb0-a7dd-d8e1979c2856
 10 38abcabe-d6a6-37f6-8219-3f9520b5e499

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 3175531023. Exactly this sequence comes out of new Random(342).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 12 of Run 36 (seed 335,015): new Random(335015), 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 2012-10-10 20:54–00:54).
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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