201211081905 12uomm

explained decrypted filler

seed 95

Metadata

Post ID: 12uomm
Title: 201211081905 → 2012-11-08 19:05 on A858's clock
Posted (UTC): 2012-11-08 11:05:24
Timezone: UTC+8 · title 19:05 against posted 11:05 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 1,296 hex characters · 648 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201211081905) = 76cb2bfff828d1737a63f407b6046e05 (name+title)
GUIDs: 20
Filler GUID seed: new Random(95).Next(9) ✓ verified
Run: Run 38 (seed 1,045,884,937) (seed)
Draw: 112 · predicted N = 20 ✓
Machine boot: 2012-10-11 03:41–03:51 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 8 · 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: 1,296 hex characters = 648 bytes = 81 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201211081905 (name+title). Key = MD5(password) = 76cb2bfff828d1737a63f407b6046e05, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 20 GUIDs as hex (shown below).

Decrypted: GUID list

  1 b2f7ab47-dcbe-3b22-be79-8e7968466d4a
  2 7de92c94-cbca-6b2e-8ccc-36f47e9af0c4
  3 97bd6aa3-6c43-1ae1-90e8-6c335a13a25b
  4 e20cd8c2-6c85-70b0-8a42-0154da9586d9
  5 c6522ab0-cfae-0a01-9ef5-65fd9ed75531
  6 3c20512e-ad81-51fb-bc9c-64cb4d473560
  7 dee8c827-2a06-4418-9044-44f50bf29f31
  8 7b1f7323-faa5-0d5c-9a08-3d93787ca2a5
  9 f5b05b17-fdb0-69e9-9bfb-17854c397ed4
 10 0cb24021-e641-2b78-b9ca-081a4c22c7c8
 11 14b0b27e-f277-27ba-960a-4bb8a2f79053
 12 20824072-8ac2-5741-babc-898a0bd88d85
 13 4d2a7253-99af-8e0a-8ace-5ec402bcf88d
 14 cd2ee13e-12e8-8a56-81bc-9d3cdda7b9cd
 15 fdd6969c-5df7-47be-89cd-d673ed1b8735
 16 ae1a7a72-561d-38e8-8045-7878d0211c24
 17 0bf66dd7-54d9-7d0a-9d95-d2eba2640a32
 18 7d7ddba5-ac78-82a8-a24b-1f6543298cad
 19 c720ea25-7ab7-205c-ae1b-137e95a8333b
 20 56fac864-6f07-09fe-bd63-bf9b5c643368

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 36170540622588437820. Exactly this sequence comes out of new Random(95).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 112 of Run 38 (seed 1,045,884,937): new Random(1045884937), Next(8,64) per post. The RNG predicts N = 20; the post has N = 20 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-10-11 03:41–03:51).
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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