201212032311 148sms

explained decrypted filler

seed 136

Metadata

Post ID: 148sms
Title: 201212032311 → 2012-12-03 23:11 on A858's clock
Posted (UTC): 2012-12-04 04:11:12
Timezone: UTC−5 · title 23:11 against posted 04:11 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 912 hex characters · 456 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201212032311) = 9d201cd8fe0c542a85d8a7ba5b254255 (name+title)
GUIDs: 14
Filler GUID seed: new Random(136).Next(9) ✓ verified
Run: Run 39 (seed 1,106,402,812) (seed)
Draw: 16 · predicted N = 14 ✓
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: 6 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

3711815B0B2B82C7 46869245629113FB 9E096153F2BE12AD D076301F75B5BD13 BBCB10739A2D888A 0D09CECD25DE78D4 B1F32E5EDDDA3F99 1E352CB26813B620 F5F6102034283EAF AF31ECFD2F021057 9A5B8E3F0F10B83A E673D53591FF5AE6 52668BB9226EA1D0 BB24DE46118CDD32 A1BE5C7F7D66B4AB 8735EAC66C4C132E C78E7001F30D5042 F8409611F33F9A02 83628612BCABAF82 7C7309E8CB8F2FA7 6513DF26BFEB72CE 12E73DF12D1D74DB E6A98008D4411417 CF7DF67F78EE6995 12D23D452C0386E9 299D66AAD61088B1 224E4BF9E8E96701 FC4F9111C594B068 78C6C122E42A6204 D0B5C887D243BAE1 A7DEF2040E23A2B6 67F3F909CAE3D81B D2759A3445124891 2E1A3E18BD7B7D4A 0BB0EF5C4BCD2FEF 2A20D491E44CB348 73068EEC1006DB81 D799DA2EE69D0D50 3C76834129A2CA54 62C7A429D415BBE3 2FBC8D22F7CDBCF9 CEA8BB7F4968676C 5B23B4E0C79602F3 1A9DCFD57F41B8CE A4C581E7F06EF920 262F71F648F59F0A 6D8D6E6A59D0298A 3161211F1FA4929C 45C0D56FB9CBCCF8 AFEF7F6D6A433EB4 98A37320BCBD375D 686CBD936AE2FE91 D94BD92E8738B8DA AA8BFB44E9BEEA73 0F4932E42A36C8A7 C9A5E49DFB1C0849 2186296495258C47

Read the ciphertext. Strip whitespace: 912 hex characters = 456 bytes = 57 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201212032311 (name+title). Key = MD5(password) = 9d201cd8fe0c542a85d8a7ba5b254255, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 14 GUIDs as hex (shown below).

Decrypted: GUID list

  1 ad433169-d9bd-63f1-91ae-d1ecde2817ea
  2 ed60266b-c5ae-60c8-b04e-54439899a0a8
  3 9abeb47c-4715-70aa-a9fb-e872d75be916
  4 14a677e4-6730-55b6-b2ce-a354436a0afd
  5 db186e86-5cb8-5dcb-b354-0199450c6fc2
  6 99be6816-0026-3876-96d9-abca8954b802
  7 f85d5591-9dea-7cd0-8eeb-1959f60811af
  8 e5bb7e2a-7804-6e6f-ba3a-6b479177246d
  9 c1b5c239-53bc-759e-8278-74865d61abd7
 10 764c4837-e3a7-3212-a276-c2859d0cf5b3
 11 f57d348a-9145-4865-92ff-39f2e4ea0984
 12 bd6a7952-8690-5ce4-b291-f3f25a801c88
 13 2bcc7052-9b09-1963-90e9-dbc230adf479
 14 995b5e09-30c2-2f5e-9684-c8dd12fc5155

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 66755376734512. Exactly this sequence comes out of new Random(136).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 39 (seed 1,106,402,812): new Random(1106402812), Next(8,64) per post. The RNG predicts N = 14; the post has N = 14 ✓. 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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