201212080600 14gt9f

explained decrypted filler

seed 9

Metadata

Post ID: 14gt9f
Title: 201212080600 → 2012-12-08 06:00 on A858's clock
Posted (UTC): 2012-12-07 22:00:30
Timezone: UTC+8 · title 06:00 against posted 22:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 848 hex characters · 424 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201212080600) = b13ba4aad8270a97b92ad266b4a0c0b1 (name+title)
GUIDs: 13
Filler GUID seed: new Random(9).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 85 · predicted N = 13 ✓
Machine boot: 2012-11-20 22:02–00:02 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 4 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

387716236D15499D 8E8D2AA074F395DB 0980A8655DAE22D3 5B37BAE603B4441D CD495513960EAF10 B5C2F6DA175D9891 59B1F2C396CEE1BE 31C0C56F872FCFC1 E45FD5684B8CFC80 47A3A6184964C36F 58A5BF929B992993 8E9578CDE0F3243B 374CC73ED5757A84 705A7EE241C302A7 8A947FB3D0DC8B88 8F9F644161FB0C08 8D1FEB148B4F9EB9 E8E300470E7B42CA 0B1727707591CFE7 1A599AC32E83B730 629A97195F451735 3C1ACDC5A82EA8F2 EB4A97040C11EEE0 E4C48091033AF5E7 3A2B4E05F5955DC2 BD038C8D4BD717AA CC38BAFCAC99C6C4 562C9F550A8A1BBA A41F6411FCBD400C C9A129B4CF6422C2 CE094CD1DDC8F3D8 95421ABF53ABC828 062C31AC9011D633 586B0F9C71887EC1 B17A49CB83A23E0D 4B3DE6D199011460 406E5BFA9C4FB4AD DC23216110D15370 9D7AEA622F216E92 5BAA7711DB43E174 26EDC79307FFA63A FFF39B03385F70D4 629D11A168267DBB 762534BF8F9B4BCC 78A3BAB24D29F83E 5B86566B965A0743 92C9C285D0CD0475 A46118D4DC3D041E CA1BC5DB88232691 5AAD662FCB11F2A9 DBA0A1F7A69A5603 FF7E4A5F59EFBDF9 EB894B929BC72975

Read the ciphertext. Strip whitespace: 848 hex characters = 424 bytes = 53 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201212080600 (name+title). Key = MD5(password) = b13ba4aad8270a97b92ad266b4a0c0b1, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 13 GUIDs as hex (shown below).

Decrypted: GUID list

  1 2939e254-4b67-3b3a-b04e-5d607442afc9
  2 77c82e17-b289-494e-9497-35e0b15111b7
  3 13838656-ded2-0ad1-9a33-07561f74be8d
  4 770bc780-459c-4080-8039-5e3f37936ca0
  5 f2b624d2-25ad-2b94-89bd-f3744479545d
  6 75aa7d6f-9225-31f3-b84f-6af5f9cce989
  7 6670937b-ae7c-8f8a-b252-c68cedd9e9b5
  8 048cd654-f02f-8c7b-b652-634bde970771
  9 9f16d4bc-29f8-03ab-89f6-be2b1cb72592
 10 a3c795ff-e6c2-5f22-899e-2dc0beca4c27
 11 35bc9446-614e-84c2-b9d7-1431948d8a9f
 12 43b1e270-f192-4d5e-9c93-1de54e9a6769
 13 3b6bfb96-8970-785f-8a5b-3bfdbd228f80

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 3404238805847. Exactly this sequence comes out of new Random(9).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 85 of Run 39 (seed 1,106,402,812): new Random(1106402812), Next(8,64) per post. The RNG predicts N = 13; the post has N = 13 ✓. The seed is the machine's uptime in ms when the app started (boot 2012-11-20 22:02–00:02).
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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