201210130100 11ej47

explained decrypted filler

seed 607

Metadata

Post ID: 11ej47
Title: 201210130100 → 2012-10-13 01:00 on A858's clock
Posted (UTC): 2012-10-13 05:00:15
Timezone: UTC−4 · title 01:00 against posted 05:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 720 hex characters · 360 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201210130100) = 9f5e9565cf50b53acd8f6686463a6f85 (name+title)
GUIDs: 11
Filler GUID seed: new Random(607).Next(9) ✓ verified
Run: Run 36 (seed 335,015) (seed)
Draw: 14 · predicted N = 11 ✓
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: 7 · 2
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: 720 hex characters = 360 bytes = 45 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210130100 (name+title). Key = MD5(password) = 9f5e9565cf50b53acd8f6686463a6f85, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 11 GUIDs as hex (shown below).

Decrypted: GUID list

  1 4221ed97-9da0-7957-93b3-660dd6598b30
  2 3ed60b7e-be9d-8fd2-9942-17fbfcbf1328
  3 bd337e54-a067-05fb-9bf0-46b405c9ea8a
  4 60f039ef-c6a6-1e32-a53c-91e4e69e5f2c
  5 021aed87-d682-2788-8efc-4f72a2221ab1
  6 80fe2f58-0a2c-0f43-a0e7-31e581bbda5d
  7 8b82c71e-d352-733c-8ad0-87349d790a60
  8 c63bf680-0454-8947-9cf6-3c7cd7c8cd24
  9 e377a4cc-f71f-0333-a5b4-863762c4adaa
 10 46b426d3-f101-03ff-8cc0-34e17b09059b
 11 084b24fd-076b-43bf-b1be-247229bcda37

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 78012078004. Exactly this sequence comes out of new Random(607).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 14 of Run 36 (seed 335,015): new Random(335015), Next(8,64) per post. The RNG predicts N = 11; the post has N = 11 ✓. 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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