201211082225 12uv76

explained decrypted filler

seed 815

Metadata

Post ID: 12uv76
Title: 201211082225 → 2012-11-08 22:25 on A858's clock
Posted (UTC): 2012-11-08 14:25:39
Timezone: UTC+8 · title 22:25 against posted 14:25 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(A858DE45F56D9BC9201211082225) = 1f72e5472a601cd8aa5983202b1a0a72 (name+title)
GUIDs: 11
Filler GUID seed: new Random(815).Next(9) ✓ verified
Run: Run 38 (seed 1,045,884,937) (seed)
Draw: 132 · predicted N = 11 ✓
Machine boot: 2012-10-11 03:41–03:51 (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)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 = A858DE45F56D9BC9201211082225 (name+title). Key = MD5(password) = 1f72e5472a601cd8aa5983202b1a0a72, 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 4fe3992b-ab65-4323-97ca-ce0b29e0774e
  2 ce8cd2b9-bacf-88de-b60a-bd818c837e6c
  3 7c63e20b-c8e9-3318-a788-9ec3cd92427e
  4 4871f530-f27f-4892-9ac8-04e8264c230a
  5 04be3ec0-6336-14b1-841d-70b2c142c066
  6 f8c8fbc3-4793-7e15-9905-3a40a27c88cf
  7 6275a42d-477c-05cc-beee-864e0e589244
  8 716e4fcc-0ee8-2a75-94b2-10dd3f11bc0d
  9 622d6dba-9deb-777f-b888-98325e9bd17f
 10 3d1b523d-4abb-74cd-a0bd-098147a7a437
 11 f4c8939b-45c4-6350-823c-5d20cb6d9db0

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 48341702776. Exactly this sequence comes out of new Random(815).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 132 of Run 38 (seed 1,045,884,937): new Random(1045884937), 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 2012-10-11 03:41–03:51).
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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