201206261058 vn1mf

explained decrypted filler

seed 759

Metadata

Post ID: vn1mf
Title: 201206261058 → 2012-06-26 10:58 on A858's clock
Posted (UTC): 2012-06-26 17:56:34
Timezone: UTC−7 · title 10:58 against posted 17:56 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(759).Next(9) ✓ verified
Run: Run 3 (seed 1,063,142,882) (seed)
Draw: 10 · predicted N = 8 ✓
Machine boot: 2012-06-14 10:25–10:26 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 59 · 27
Tags: automated (decryptable)2012Encrypted masked GUID listkey: namerun: seed

From the post to its content

As posted (encrypted)

0A9AC63432328DA9 C46E6AA806BF4259 9B9FEA2A4774ADE0 510692B1DD8C37D5 BB69E9F7F5036137 B2F6CAAA55311EED 9FFA987B368D03A7 44F3686AA97174CF 730F4B955D5332B0 53C1FD2C8E939593 D384C112CBC49F37 356F9408FA0A4844 4868217919258359 810A05866A4E3276 F6E6013A3124126E B7ED251541909BB2 30027D3B35057800 6DAC5B0E8F85E836 F9CAFD831B056E7A 92A8937C7A6D285C 0D9DB25D6F4CE695 62B72A24CDD8DBC0 3FE58EC0E060D881 46A9E0E62ECA6F80 0395F4264A53FCC3 EF65EC3219BE6288 BD317B610A3D4E71 D20D9DE1D4B17EEA 67FA0AF83D1F1AE2 CE712DE394E3C3C4 D4B7909D70ABEAD3 332AE28419DF853F 5DACFFBA8FF64DBD

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 4a895f45-35e1-283c-8b9f-738c969a28ed
  2 762e8238-ba08-47f4-b2aa-37014ff3d572
  3 cb4f681f-b48e-2dd0-87f2-bd7a7e5e79c0
  4 474a0e6a-66c1-5d99-a2bf-57a1ef329234
  5 820195be-5e5c-7e38-9db8-9900874df4e5
  6 7fed3c5e-9a42-7881-b3c0-8a89eed3ac9a
  7 3e4e68b7-2026-8714-aa71-c2bdddfec3ac
  8 f7780a7e-c27c-1390-b31f-756ad58bc646

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 24257781. Exactly this sequence comes out of new Random(759).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 10 of Run 3 (seed 1,063,142,882): new Random(1063142882), 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 2012-06-14 10:25–10:26).
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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