201211082205 12uuam

explained decrypted filler

seed 275

Metadata

Post ID: 12uuam
Title: 201211082205 → 2012-11-08 22:05 on A858's clock
Posted (UTC): 2012-11-08 14:05:38
Timezone: UTC+8 · title 22:05 against posted 14:05 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 912 hex characters · 456 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201211082205) = fca91f78ed151d2800bf89c43a594a5b (name+title)
GUIDs: 14
Filler GUID seed: new Random(275).Next(9) ✓ verified
Run: Run 38 (seed 1,045,884,937) (seed)
Draw: 130 · predicted N = 14 ✓
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: 912 hex characters = 456 bytes = 57 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201211082205 (name+title). Key = MD5(password) = fca91f78ed151d2800bf89c43a594a5b, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 14 GUIDs as hex (shown below).

Decrypted: GUID list

  1 942099c1-2215-3fbf-b881-25bfc10e8e76
  2 9177192f-2424-4bd1-bbd4-b2bd0f6624c3
  3 6e4d32ac-1d1c-8cc9-9170-0856ba8028f3
  4 cd9ff479-76e3-2883-a186-acc1be52c463
  5 464e0af3-6087-368b-a259-09b14b3652b7
  6 0841c78d-10a0-7af2-b6b3-43973f4080de
  7 7ef5e40a-d323-1ed9-9850-840cdb6cd893
  8 349f7549-d730-338b-b6e6-7c717b4f249d
  9 e9ac014c-52a2-895f-9f0f-2ae16ce002d7
 10 314d9a00-ddaa-6317-bbc1-594bf559e073
 11 7ef9adbc-7a54-8e86-835e-58f5aec85f3d
 12 c8a5f6d6-2e8a-18e9-951b-35e6ce5664c6
 13 7ab32823-6ab6-6903-a10c-65a2da3ef376
 14 7a0dd149-e464-4e90-baef-e61cef8e8f49

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 34823713868164. Exactly this sequence comes out of new Random(275).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 130 of Run 38 (seed 1,045,884,937): new Random(1045884937), Next(8,64) per post. The RNG predicts N = 14; the post has N = 14 ✓. 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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