201209212130 10a1zz

explained decrypted filler

3DES(name+title) ECB, 12 GUIDs, seed 864

Metadata

Post ID: 10a1zz
Title: 201209212130 → 2012-09-21 21:30 on A858's clock
Posted (UTC): 2012-09-22 01:30:03
Timezone: UTC−4 · title 21:30 against posted 01:30 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(A858DE45F56D9BC9201209212130) = c73c6da58cd999fd9aabed614a4d030c (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 12
Filler GUID seed: new Random(864).Next(9) ✓ verified
Run: Run 33 (seed 1,220,410,968) (seed)
Draw: 3 · predicted N = 12 ✓
Machine boot: 2012-09-07 21:49–21:59 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 9 · 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 = A858DE45F56D9BC9201209212130 (name+title). Key = MD5(password) = c73c6da58cd999fd9aabed614a4d030c, 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 7af1b70d-677d-0e39-b9b8-2e3ecb56f709
  2 b54704c0-b824-26bb-b76b-6bd134fda2d0
  3 ff2e70bb-63a1-645f-9d11-6d0cb435a5ad
  4 00c48c0b-ed1f-80e5-a426-9a8b6879bb45
  5 d92a22ee-9540-2f5f-bcb2-c1d8ad33ecce
  6 0d5a705d-f78e-5045-a74e-8e6bbf93a972
  7 f193cbf0-ad3a-0d3a-ba96-6e6bcb1e149c
  8 29aedc6d-4496-84ef-975c-13ef05eb55eb
  9 9737e03f-a12f-7914-8a42-64c23c454b01
 10 b5acdb10-8674-7505-8a16-a2fb2a1b4665
 11 c79f0aa5-46a1-7f28-ac04-723e989a97fe
 12 b0755ca3-ed0b-08da-9233-aabbbb1c7d9a

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 026825087770. Exactly this sequence comes out of new Random(864).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 3 of Run 33 (seed 1,220,410,968): new Random(1220410968), 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 2012-09-07 21:49–21:59).
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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