201309171832 1mlq33

explained decrypted filler

seed 647

Metadata

Post ID: 1mlq33
Title: 201309171832 → 2013-09-17 18:32 on A858's clock
Posted (UTC): 2013-09-17 22:32:59
Timezone: UTC−4 · title 18:32 against posted 22:32 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(A858DE45F56D9BC9201309171832) = 21e945f398d4086f0f8ffe327a29184f (name+title)
GUIDs: 8
Filler GUID seed: new Random(647).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 106 · predicted N = 8 ✓
Machine boot: 2013-09-12 09:30–10:30 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 0 · 0
Tags: automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: 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 = A858DE45F56D9BC9201309171832 (name+title). Key = MD5(password) = 21e945f398d4086f0f8ffe327a29184f, 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 3e54609e-e372-6e82-9839-c24d2f23bb1c
  2 e78f7e56-c0ab-517b-b3d8-6710a8c94051
  3 5430d373-d03d-0f60-84d8-d4fa2b8e87a8
  4 6bbce4b0-67e9-59d9-9be1-f7d503f277bd
  5 d522032a-d08a-2694-a962-7d05a746a77c
  6 4bbf67ae-d6b2-8da7-856e-82b40dab41e6
  7 03d7a249-aee4-7ccc-be2d-47956e5b1e2a
  8 446b9ff3-9bb4-007c-b692-39ceefc81cd6

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 65052870. Exactly this sequence comes out of new Random(647).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 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) 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 2013-09-12 09:30–10:30).
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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