201309251914 1n50kg

explained decrypted filler

seed 377

Metadata

Post ID: 1n50kg
Title: 201309251914 → 2013-09-25 19:14 on A858's clock
Posted (UTC): 2013-09-25 23:14:58
Timezone: UTC−4 · title 19:14 against posted 23:14 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,040 hex characters · 520 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201309251914) = d51d9b5982c26c3e514d3003e73c5f02 (name+title)
GUIDs: 16
Filler GUID seed: new Random(377).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 136 · predicted N = 16 ✓
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: 13 · 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: 1,040 hex characters = 520 bytes = 65 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309251914 (name+title). Key = MD5(password) = d51d9b5982c26c3e514d3003e73c5f02, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 16 GUIDs as hex (shown below).

Decrypted: GUID list

  1 100e3a5c-0aaa-66d9-b090-dcd768c1af77
  2 a8b8abad-c043-3086-8eb7-f414ffef9e27
  3 c4199482-ba89-2b87-b208-43e296c76469
  4 4f10b7cf-ddbd-0ab6-aee0-ea8ff1171620
  5 fa0d7e5d-3b08-38a9-bb5d-84a6b8be4ea5
  6 7ce89891-5ba6-0e84-985c-7b2b99360f81
  7 5920857f-db8d-75f3-89f7-2433868fea08
  8 d1b13704-76bc-5227-9b75-2fd5d83de107
  9 e12a6fd5-fa86-5f8a-bca5-417ff448c1a4
 10 e9ef242d-6bfc-280d-99e7-1788179d6c52
 11 e8fc2560-b963-0011-bb54-086819572bca
 12 4da63936-0231-753b-baed-6d2df6875e78
 13 c754d5c2-daf1-74ff-b0cf-17ea473a494e
 14 80462b2c-68eb-5d41-8883-769a1018647c
 15 f72dc3b3-379f-7c64-8011-e42b557f6dbc
 16 68bf8b49-7722-465c-8238-e9611e3fefe7

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 6320307552077574. Exactly this sequence comes out of new Random(377).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 136 of Run 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) per post. The RNG predicts N = 16; the post has N = 16 ✓. 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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