201212041435 149ymy

explained decrypted filler

seed 271

Metadata

Post ID: 149ymy
Title: 201212041435 → 2012-12-04 14:35 on A858's clock
Posted (UTC): 2012-12-04 19:35:29
Timezone: UTC−5 · title 14:35 against posted 19:35 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(A858DE45F56D9BC9201212041435) = 677d761a1f31eebbf06c0347c9de545d (name+title)
GUIDs: 14
Filler GUID seed: new Random(271).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 44 · predicted N = 14 ✓
Machine boot: 2012-11-20 22:02–00:02 (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 = A858DE45F56D9BC9201212041435 (name+title). Key = MD5(password) = 677d761a1f31eebbf06c0347c9de545d, 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 6a1fb26a-2b37-287c-855b-51b2ca9796b4
  2 f7b14428-5fe2-3c00-bb42-d99d90991df5
  3 c6a6b8c6-7dd4-14c5-914b-14d979621c3d
  4 5f1a8769-cef4-32a1-95fb-d4adfc91d5c0
  5 c369b5f0-c425-5e8e-8f29-e498efa8ad32
  6 0097a180-7d6b-300b-9e03-452495865c29
  7 36222c46-9a1f-247a-879b-be9106078f5f
  8 e3d1a272-546b-3108-9b8e-445f5b56476b
  9 c4444e97-c664-4511-b754-bbbee3501552
 10 06d0f9a9-d332-10a6-8f8c-ad0f21ec40d0
 11 dbdb4622-fcc2-8a31-a394-4c7df9b8bc75
 12 12a920e8-b106-0716-831c-1e3b0d8d360e
 13 d41d4994-9183-8df7-8152-72ab2d7a50cc
 14 1b5bf18c-9ac1-4e7f-afea-1d0f56fc5b70

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 23135323418084. Exactly this sequence comes out of new Random(271).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 44 of Run 39 (seed 1,106,402,812): new Random(1106402812), 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 2012-11-20 22:02–00:02).
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

Related