201209271230 10l5s9

explained decrypted filler

3DES(name+title) ECB, 10 GUIDs, seed 757

Metadata

Post ID: 10l5s9
Title: 201209271230 → 2012-09-27 12:30 on A858's clock
Posted (UTC): 2012-09-27 22:30:04
Timezone: UTC−10 · title 12:30 against posted 22:30 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 656 hex characters · 328 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209271230) = d15685a97baae9306cff3b45cb8ef87f (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 10
Filler GUID seed: new Random(757).Next(9) ✓ verified
Run: Run 34 (seed 83,105,000) (seed)
Draw: 270 · predicted N = 10 ✓
Machine boot: 2012-09-22 10:23–10:24 (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: 656 hex characters = 328 bytes = 41 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209271230 (name+title). Key = MD5(password) = d15685a97baae9306cff3b45cb8ef87f, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 10 GUIDs as hex (shown below).

Decrypted: GUID list

  1 79b77cce-fae0-1941-8107-896f36c53433
  2 7564d6f7-f56e-8b10-90a7-10cffe61c69c
  3 fd36b485-2aaa-8320-ad93-411d7e03f687
  4 ce9a9f30-2fda-1bc3-8292-ab149a850c90
  5 63a817df-5dd2-8b9a-b4d8-b21fddec2cc8
  6 bad8eb8a-3528-086c-8511-1b20acd0e735
  7 cf68d43d-8290-01ad-bd9e-bd8690dbe597
  8 64e0b420-6cc1-15a8-ab01-ded4d8f462fe
  9 77708ad1-7629-5867-b66f-8ad27a80ccbd
 10 9136ff74-dad5-3470-be66-35f903410d64

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 1881800153. Exactly this sequence comes out of new Random(757).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 270 of Run 34 (seed 83,105,000): new Random(83105000), Next(8,64) per post. The RNG predicts N = 10; the post has N = 10 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-22 10:23–10:24).
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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