201206271149 votps

explained decrypted filler

seed 671

Metadata

Post ID: votps
Title: 201206271149 → 2012-06-27 11:49 on A858's clock
Posted (UTC): 2012-06-27 15:47:14
Timezone: UTC−4 · title 11:49 against posted 15:47 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9) = 34a14a42e98ff96095af56604e290cae (name)
GUIDs: 8
Filler GUID seed: new Random(671).Next(9) ✓ verified
Run: Run 8 (seed 593,707,075) (seed)
Draw: 1 · predicted N = 8 ✓
Machine boot: F 2012-05-15 18:59–19:19 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 5 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: namerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9 (name). Key = MD5(password) = 34a14a42e98ff96095af56604e290cae, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 382e99ee-ceb8-28bf-a76d-3ca4d88c568d
  2 3fcc8c29-d311-6b09-b4d2-638d83540f26
  3 18be01f8-8422-72d4-9ad0-76ca808a63b9
  4 94f6aa79-8043-785f-96da-ddb7cd669de4
  5 6c71abf2-782b-14e8-bd7e-aa73493374d4
  6 f84959c6-80e9-817f-a311-84fbff06dc6e
  7 7d751a0d-8d7e-4cea-8fd0-440ba838d83e
  8 6042ec96-e0da-08a8-ad7d-62c0988d6e25

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 26771840. Exactly this sequence comes out of new Random(671).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 1 of Run 8 (seed 593,707,075): new Random(593707075), Next(8,24) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot F 2012-05-15 18:59–19:19).
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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