201210021620 10u27c

explained decrypted filler

3DES(name+title) ECB, 12 GUIDs, seed 587

Metadata

Post ID: 10u27c
Title: 201210021620 → 2012-10-02 16:20 on A858's clock
Posted (UTC): 2012-10-02 20:20:31
Timezone: UTC−4 · title 16:20 against posted 20:20 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 784 hex characters · 392 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201210021620) = 6c107b28fa01bebb63760300ac865f7a (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 12
Filler GUID seed: new Random(587).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 37 · predicted N = 12 ✓
Machine boot: 2012-09-22 10:16–10:36 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 784 hex characters = 392 bytes = 49 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210021620 (name+title). Key = MD5(password) = 6c107b28fa01bebb63760300ac865f7a, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 12 GUIDs as hex (shown below).

Decrypted: GUID list

  1 41e4df31-99da-3ada-9e9f-80c2ebb63b32
  2 df18eb59-d6ee-07f1-b2e9-d9cfaa5e7261
  3 2b4a355c-4615-0f67-b494-457717fcfd7d
  4 5b3a062e-437b-78a4-9f34-5fe3d641f253
  5 c6b2d960-7da3-293e-9caa-0052eb9f4286
  6 71b10f3a-6dba-42be-8488-7291a1e82d51
  7 4624f9b9-4013-8e6b-bb1d-bf1311ff1e80
  8 66e381ae-f19d-877d-a096-0047b97c2a73
  9 859b2110-6951-59eb-93ed-492733d08cc0
 10 ea6fe402-a012-68f6-a12c-c585c0c87a5c
 11 cd08e2c7-0898-6b7e-a09f-4fa8b4f478e5
 12 eec8110a-5b28-6f29-a4fe-a39ddb764818

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 300724885666. Exactly this sequence comes out of new Random(587).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 37 of Run 35 (seed 854,622,578): new Random(854622578), Next(8,64) per post. The RNG predicts N = 12; the post has N = 12 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:16–10:36).
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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