201309101259 1m3fbv

explained decrypted filler

seed 812

Metadata

Post ID: 1m3fbv
Title: 201309101259 → 2013-09-10 12:59 on A858's clock
Posted (UTC): 2013-09-10 08:59:48
Timezone: UTC+4 · title 12:59 against posted 08:59 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: F3 filler: 3DES(name/title) → GUID list, seed known
Size: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201309101259) = a52f42b61388be04515ebbdc133d180a (name+title)
GUIDs: 8
Filler GUID seed: new Random(812).Next(9) ✓ verified
Run: Run 52 (seed 1,430,705,843) (seed)
Draw: 84 · predicted N = 8 ✓
Machine boot: 2013-08-14 07:34–10:34 (seed = uptime at app start)
Sources: community-archive, arctic-shift · body from community-archive
Links: Reddit · Arctic Shift · JSON
Score · comments: 4 · 1
Tags: automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

B1B11D165CFB5965 AFDEE6A2121348F7 B30A3DA961BC4FE5 498EADC679E1AFF8 234A070E28C997EE 3768EDB3DFA68449 B0A1FF247DF85679 761939ED9C9373F1 529A599A13571AEE D117D6E9C1801F59 3FDC106024CE1A9E 8923D0EC9958B9AF 635F5EAE90927729 7BC27CECC353827A 5A3A0EDD6ECCEC65 9F461B2E039CC146 8AA014F9AA2E4E21 84E968B2557658B9 20624D15E3A601D7 51B389F2AFAB9C88 4282E913965BADBF 19559D3D162C4841 E41A68254B26D98F F6794D258288198E AD934EADFA53EF09 D9144F2F5E193DAE 7C82C6A02CABCF9D 54384B7D18F9592C AC77EC822D91AD68 F5841D2F6198F854 72447773A1013C15 1DF104F47E6E60B4 71F6F3475581BB38

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309101259 (name+title). Key = MD5(password) = a52f42b61388be04515ebbdc133d180a, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 928753b8-61f5-8cbc-a8b1-0f6b1f975430
  2 28a161ba-501a-0e50-a2b2-6e797cddf846
  3 39f242a8-5cdd-3eac-a716-1fec12a5e242
  4 99a9be5e-6499-7501-80d2-0670b8184d9c
  5 1f3104b2-b28b-70e5-ad1a-34c42b0f11bc
  6 30e11a74-b170-10a4-8346-8102a385ee59
  7 2b84c82a-d028-6241-914a-3aaec8aca5d1
  8 f6a0b31d-3c70-75e5-a20b-f86957365cff

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 80377167. Exactly this sequence comes out of new Random(812).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 84 of Run 52 (seed 1,430,705,843): new Random(1430705843), 4·Next(1,12) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot 2013-08-14 07:34–10:34).
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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