201209200945 1060rn

explained decrypted filler

seed 55

Metadata

Post ID: 1060rn
Title: 201209200945 → 2012-09-20 09:45 on A858's clock
Posted (UTC): 2012-09-20 00:45:16
Timezone: UTC+9 · title 09:45 against posted 00:45 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 592 hex characters · 296 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209200945) = 89b23ce0d1fc04da5935b24c2484acad (name+title)
GUIDs: 9
Filler GUID seed: new Random(55).Next(9) ✓ verified
Run: Run 32 (seed 945,377,703) (seed)
Draw: 16 · predicted N = 9 ✓
Machine boot: 2012-09-08 22:08–22:23 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 9 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

51B5B1A5FBDACBEF F5F440F02FC11FFE 74539BA5AF792C93 BDB95F3B59B9E284 4B1239FF2FF1C0D9 B7DCC98CA4696336 413339803B283FCE DC1D5E0A666FBF85 72A6DF7924E87FFD 819E40EB18C0B656 03E7F365838ADDBE D1259EC90BECF723 5D3BC2B7CB976BB0 5BBAFC422ABC4887 1ADB9E8E48BE0B64 F40477F4558C00FF 96D329D7791434FA 6DB79C5787EFA344 F6E63B99E4571433 EF829D1DA16B5F9E C21DCBDB0F95A01A F2C9F28446EB8A4A CC260FD877CC494A DBC5DD44CAA5CFFF 7406E180D30693C2 B12A83FD482132A6 C33CEA9C2A14D7E6 F68A9BBFD4DFA1B2 E63A009B8C227B5F E1246F1E387DE14F 57647DDA4CDE9449 36A594F03709B50F 2C401C9F9FD0074F B87190AC82708306 0DE96B8C42763BD2 3E5F3184659569AE F0DA7D6BD2E8137C

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209200945 (name+title). Key = MD5(password) = 89b23ce0d1fc04da5935b24c2484acad, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 9 GUIDs as hex (shown below).

Decrypted: GUID list

  1 97aebb82-f927-4e21-80fd-a3128dd35876
  2 c36c90f3-b696-8a2a-bf36-2ad8b3e6e34f
  3 796e5af6-2d4c-1b2e-a71d-dc4b2bf7d8e6
  4 54306ac5-a0bd-2732-b3de-734a77b3b3c4
  5 d2263ef5-92a2-062f-a89e-a25e4c04f1ab
  6 81e0fee8-1d8d-55cc-aab1-23112aa2c3e8
  7 30149d10-8a08-4ea5-81a7-e47a0adc5382
  8 76e5324f-cdb4-080e-b3d3-af79fde1de7d
  9 452642c1-e0c7-7696-be9e-a3753440c093

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 481205407. Exactly this sequence comes out of new Random(55).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 16 of Run 32 (seed 945,377,703): new Random(945377703), Next(8,64) per post. The RNG predicts N = 9; the post has N = 9 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-09-08 22:08–22:23).
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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