201210102000 118vqq

explained decrypted filler

seed 310

Metadata

Post ID: 118vqq
Title: 201210102000 → 2012-10-10 20:00 on A858's clock
Posted (UTC): 2012-10-10 11:00:29
Timezone: UTC+9 · title 20:00 against posted 11:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 592 hex characters · 296 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201210102000) = 340afa2aee3e129bdfd01a6280bd849a (name+title)
GUIDs: 9
Filler GUID seed: new Random(310).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 525 · predicted N = 9 ✓
Machine boot: 2012-09-22 10:16–10:36 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
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: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210102000 (name+title). Key = MD5(password) = 340afa2aee3e129bdfd01a6280bd849a, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 9 GUIDs as hex (shown below).

Decrypted: GUID list

  1 8d6b6bbf-8eb8-6d79-bcdc-bb066250d412
  2 2673cc60-8fd2-60d6-8b7a-5b9ff2886507
  3 d41fe625-360a-4dd4-8975-ee15905b1ab9
  4 acedfd20-55f9-64e0-bcf9-a08c61b2022e
  5 c17bfa5d-4fb2-14c5-b655-e516b0677ac2
  6 0a865e01-91cf-4fcf-86f3-00b80f5fc892
  7 f411de85-2ee7-7237-bef0-6b88a0aed5f9
  8 e4dae682-4750-8897-b53a-29e56d2cea88
  9 6cab5fb8-659b-2686-b6fd-a32fb567343f

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 664614782. Exactly this sequence comes out of new Random(310).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 525 of Run 35 (seed 854,622,578): new Random(854622578), Next(8,64) per post. The RNG predicts N = 9; the post has N = 9 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:16–10:36).
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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