201209080300 zjpwp

explained decrypted filler

seed 470

Metadata

Post ID: zjpwp
Title: 201209080300 → 2012-09-08 03:00 on A858's clock
Posted (UTC): 2012-09-08 07:00:02
Timezone: UTC−4 · title 03:00 against posted 07:00 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 592 hex characters · 296 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201209080300) = d6cdca07f1355007c97c90c74df7a8d9 (name+title)
GUIDs: 9
Filler GUID seed: new Random(470).Next(9) ✓ verified
Run: Run 31 (seed 15,917,281) (seed)
Draw: 2 · predicted N = 9 ✓
Machine boot: 2012-09-07 23:34–00:34 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 1 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

11D4D42418530315 CCE03C3495AC8B61 C5F458216156D676 8463104D8C55A671 DFC5E84DECDDCC6C EAFCA1377D78C6D7 26CE361A7A14E5BD F67FAB24A46C3802 C03FE72D5D887E67 A25582D30852FDDE 639535704B0FA2A6 CDF7FF5BB341DB7F 873286CCAF6260A0 A9138507F3DCB9A5 8BB4E794A645F6F1 652075FF9DBE8E6D 7BC6DE57BB652F33 11E6F575CF57A0C5 B8368C9084BEFA2A 24154F7D2562DEE5 13AE83263691FEF7 9543043509A48326 0B2671F2714E9801 7A2AC60E5D558DEB 5BEF77BEC79702D6 CEB9B99E17D6B773 BE79686A7127BCA9 CA86AD8AB79F3789 D06DECEE436C85B7 C76D611DAD08A1F9 22DC9B06277718BA F48678A6CE3C18B9 FFCD9F57878089C5 C3B310C583062CE0 CED3AE1542DE43DC CAF4640829CCF1B1 C17C3A0E1EA68525

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201209080300 (name+title). Key = MD5(password) = d6cdca07f1355007c97c90c74df7a8d9, 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 af3bd83b-4e0a-29b2-a785-9088fd835787
  2 9497822b-36b5-6628-ab57-6aa861cc1e61
  3 40435b15-8f5d-24a7-bcdb-c530d0c72cea
  4 bf71879b-2dc0-7cee-a6de-8422053cb5f7
  5 754200e4-0985-3a23-a2e0-ca6466044024
  6 3fdc797a-63b3-2217-9bb5-b34ed8f5375c
  7 7d5d8e82-c34d-4899-9ded-32ceecc2151a
  8 0f597aa8-1603-2062-baa0-a1befc53fe27
  9 2ab735ff-bd09-182d-a507-8f89e06fa363

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 262732421. Exactly this sequence comes out of new Random(470).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 2 of Run 31 (seed 15,917,281): new Random(15917281), 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 2012-09-07 23:34–00:34).
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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