Bitcoin Forum

https://blockchain.info/tx/455e64c2ffaf40ba8b1d2f0443f7ddb880bd2251431480a31faa7009041e60d2

multisig 2-of-3 (two signatures of three persons)
where each 'person' - is also multiisig 1-of-2 ?
this is funny.

       "52"          // 2
       "6b"          // toalt
       "51"
       "210269fdfceccb4b7a2fac99bde52e1a23b4b257a16ddbc91e17ebbe1299c9bf8a80"
       "2103bdbd61f48e79213ff7c05a6a9a7027642911170346c05c10e2fa35a848e7c504"
       "52ae"
       "636c8c6b68"  // if { fromalt 1sub toalt }
       "51"
       "2103e2e957c8ea1b0c56ec8820b10b6b9ca76074da6a176f0fae9a2d3975f14d2563"
       "2102d7ebe6b06b97d866efe5c7650ccf65fb4f17ffe69b10c0333e9421b8d6d5886c"
       "52ae"
       "636c8c6b68"  // if { fromalt 1sub toalt }
       "51"
       "2103a36b65fd0a7f928cd96a399a29cd31988c0e29f6e696d0be9d58f57c02021833"
       "21029fb6694ccd1b075c1abe6147eac32971bc099db052ef5370124625ecddc8577f"
       "52ae"
       "636c8c6b68"  // if { fromalt 1sub toalt }
       "6c91"      // fromalt op_not

http://webbtc.com/script/455e64c2ffaf40ba8b1d2f0443f7ddb880bd2251431480a31faa7009041e60d2:0

This is a draw out for anyone interested.

Cool, I didn't know this was possible.  What is going on here? Why?? 

This is funny, but I do not know the practical reasons for such thing. (I am not a creator of this address)

Well known 2-of-3 msig address can be redeemed by any two of three persons.
Say, Alice has [key_alice] Bob has [key_bob] and Charley has [key_charley]
Any two of them can redeem the output.

Now Alice has two keys [key1_alice] and [key2_alice]
She can sign this transaction with any of them up to her choice.
The same thing with Bob and Charley.

1-of-2 is an interesting case, but you could think of plenty of practical applications.

Say just for business management. A semi decentralized company operating on blockchain technology/with cryptocurrencies has two or three departments. For any major purchase two departments have to be in agreement -- that is the parent 2/3 multisig. Then inside each department, there are multiple managers -- which any one of can approve the expense for that department, but two can as well. While the practical spending of the tokens are irrelevant to the amount of N in the 1 of M multisigs, it allows for additional accountability having the ability for more than the required amount to sign it. Additionally, once you start abstracting to concepts other than just currency management the range of possibilities of application expand greatly; It could apply to voting or other various blockchain tech systems utilizing multisig for a n-of-m consensus outcome and the smaller 1 of M bundled inside for more detailed record accounting. Of course, these are simple concepts just of the top of the head, but im sure plenty of much more utile creative uses could be brainstormed ;]

a traditional bitcoin address has only one private key to sign transactions. Multisig bitcoin addresses requires signing of transactions with one or more addresses. A company could own an address where multiple addresses are required to spend the transactions.

In this example, it appears that out of a group of three persons, two must sign the transactions. Normally that means if you have 3 persons:  Derek, David and Dorian then 2 persons must sign it.  But in this example, the two signing addresses are also multisig addresses.

In pseudo code:

This can become very confusing when observing it. Especially if we have a multisig in a multisig in a multisig of which some are 2-3, others 1-2 and so on.  

Seems cool. Maybe the 1-of-2's are a cold wallet key and a password derived key for access anywhere? Interesting to see this, I wonder what the use case is!