201210041542 10yayi

explained decrypted filler

3DES(name+title) ECB, 9 GUIDs, seed 105

Metadata

Post ID: 10yayi
Title: 201210041542 → 2012-10-04 15:42 on A858's clock
Posted (UTC): 2012-10-04 19:42:26
Timezone: UTC−4 · title 15:42 against posted 19:42 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(A858DE45F56D9BC9201210041542) = bf20a8c255647e2feff741d53260c55e (name+title)
New here: Missing from the community archive; decrypted here for the first time. (new results)
GUIDs: 9
Filler GUID seed: new Random(105).Next(9) ✓ verified
Run: Run 35 (seed 854,622,578) (seed)
Draw: 179 · predicted N = 9 ✓
Machine boot: 2012-09-22 10:16–10:36 (seed = uptime at app start)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 8 · 0
Tags: automated (decryptable)2012Encrypted masked GUID listarctic-onlykey: name+titlerun: seed

From the post to its content

As posted (encrypted)

1000DFBA5CAC302D 2888182ACF376081 7AA764192DA2A7AA 1780CA993BC0849C E2D15B58126BBFCD A8C4001E24AC1D08 77AC6EC4626BAA31 EA106FF8C2BDAEED 2E12AD448C6D0D18 A2E5D7765B9E9040 2834EF58CB11B5FD 60333E11ED564C4C D8D80D2C4A9C5E7D 183BE146EEFF0A75 3822F04EA1536E17 F2C67D0EC6FC754D 376F2421C4E3116C 0A6915CC1ADE79E4 18CB7F3BD22F94E8 55FC59F93EA19EEA 01B79BCEB00B17F2 21A111B62A374BF2 A85526D1C3DFFB5C D1F12166B71BFB33 76D6384093B08A75 B4EAF10963955DF1 3EFCF3E5199EA235 70717B43F8839793 1B7901218A08EE4F BCDA2DBC1A8A9A0D 49E4450B1859DE3F 19A85B0D2109EC85 1120E921223B3793 B8273DE8BBC70768 21E84E7970BE6B57 248A0F42E482EC26 D9E6E40566B16484

Read the ciphertext. Strip whitespace: 592 hex characters = 296 bytes = 37 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201210041542 (name+title). Key = MD5(password) = bf20a8c255647e2feff741d53260c55e, 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 03c8dec4-ed9a-5e00-854c-88680c31c45a
  2 8447e8fc-e4ed-53d2-96f1-54a3aa0f44d6
  3 197a3359-4d0e-14ad-9d43-19df9967f4f6
  4 ba3779c0-68b9-8158-b04a-457b0c5cd366
  5 75e3e0c3-7f93-520e-ac33-e6a4af2367df
  6 039c022c-d656-2670-a8c3-f146a5746243
  7 275919b7-631c-8854-a4a7-a95b86ecdd31
  8 59beb4b8-1656-1eb5-81f0-1841c4586a78
  9 d14bbe95-424d-87ff-8369-9e2f9170fc15

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 551852818. Exactly this sequence comes out of new Random(105).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 179 of Run 35 (seed 854,622,578): new Random(854622578), 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 2012-09-22 10:16–10:36).
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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