201309270714 1n8p2d

explained decrypted filler

seed 506

Metadata

Post ID: 1n8p2d
Title: 201309270714 → 2013-09-27 07:14 on A858's clock
Posted (UTC): 2013-09-27 11:14:56
Timezone: UTC−4 · title 07:14 against posted 11:14 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 784 hex characters · 392 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201309270714) = 74e3d9f004058884377551f4dae2e42c (name+title)
GUIDs: 12
Filler GUID seed: new Random(506).Next(9) ✓ verified
Run: Run 53 (seed 26,950,390) (seed)
Draw: 139 · predicted N = 12 ✓
Machine boot: 2013-09-12 09:30–10:30 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 11 · 1
Tags: automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

A5861B691706F993 C937540B5935621D C3EF2101D0CC67BB D57903D5E602144B EA691BA88CF49C20 B26E5DCACE49EFCB 5B06D55002A669A3 3C30E9466B188B4A 718C6FF8DAE694A7 341F7FF32AA0DE18 C1BC5FC89ED6EF6B 06566BFE2003D5DE 321AE6FC0B909716 833D5845E1970375 3DF0A4DFB9411087 6FBEBBD4BB4CED7E BD473B82DBF699F3 5C11ADFC3A771E37 0630613EA941D2EC 06CFE9282BC01377 578B8091FDB31526 E4E979C8D493BDD0 6B5A90DB6A3DB27A 8BFE29F87413EE00 43DDDE75099B600C 92130B91B319629B 2897D58CEA756958 3477CF626BB4B54C BA89016380CB2BB9 79C99BE07424D5C4 4DBFE32C8F91762A 390FE42F7404E4D7 BD2669766CA52748 F5990D1521FBA405 2DA6A2A9C80A5B04 4BA300E03CADE9D9 970C5371858295FE 436EBBA6A62E7502 5636EFB684345D18 38655F2A5BBE329A 72D35A1DB9DB0D0B B9EC7C6EF7538DC6 87B3E8923ED45065 A9FB0A6E61F57DF4 11107F69042B3167 2B1C9551FE85DC34 194392A3990ED123 6509CBD456B7FDAE 1CFCEAA3F01297FA

Read the ciphertext. Strip whitespace: 784 hex characters = 392 bytes = 49 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309270714 (name+title). Key = MD5(password) = 74e3d9f004058884377551f4dae2e42c, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 12 GUIDs as hex (shown below).

Decrypted: GUID list

  1 fdd2cad2-ea88-035f-be8f-6abe383a58a3
  2 7619a901-5f47-27e5-9c9a-dd280493f71b
  3 dd82821a-ea72-4fea-a7be-5eeb90874e83
  4 aa4d19d9-f140-5747-ade2-ba6b37a9f2bf
  5 72279aa5-75c6-5e57-96e8-83827efb806b
  6 017268d6-6516-61d1-919e-d6fbf964ebd1
  7 8fed160e-3db5-55ca-9810-8056626db298
  8 79a5b9b8-d63a-2491-b298-e71375de982d
  9 e5055f6b-9adc-576c-9736-8151d8ff3bad
 10 31786224-dde5-7aeb-8a6f-c4814ec67a5a
 11 78044862-a405-0b69-8916-137f689b0441
 12 1d15a6ea-8e2e-4588-bfd2-ad07ce88ea10

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 024556525704. Exactly this sequence comes out of new Random(506).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 139 of Run 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) per post. The RNG predicts N = 12; the post has N = 12 ✓. The seed is the machine's uptime in ms when the app started (boot 2013-09-12 09:30–10:30).
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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