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Author Topic: Private Key Sharding, How is it Secure in a Distributed Network?  (Read 104 times)
UnruffledST
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October 11, 2018, 02:10:53 PM
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In a Distributed Network in order for a Private Key to not be compromised sharding will have to take place off the network, correct?

If so why is it that when a Distributed Network shards private keys are they so worried about it being comprised in the network when the sharded keys are encrypted? does decryption take place in the Network? If so why can Decryption not be done off the network?
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October 12, 2018, 04:58:37 AM
Merited by DarkStar_ (1)
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i honestly have no idea where Private Key Sharding is used in cryptocurrency! if you know an actual case i would love to hear it.
but basically it is the Shamir's Secret Sharing[1] that you are talking about. the security behind it is from the math that is used to create the polynomial over the finite field.
there is no encryption or decryption in this case. you only have "shards" or parts of a secret that in a way you append to each other and then extrapolate to get the "secret".
take a look at this[2]. for example you have a private key that you split into 3 parts and store each part separately in different places.

the reason it is not used (to my knowledge) is exactly because you have to share the secrets and that is not desirable. in bitcoin what we have instead is multisignatures. which means you need multiple secrets instead of 1 that is split. and the benefit of it is that you don't have to share these secrets, you simply partly sign the transaction with your key and pass it along to other parties to partly-sign.

[1] https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing
[2] https://github.com/blockstack/secret-sharing

In a Distributed Network in order for a Private Key to not be compromised sharding will have to take place off the network, correct?
keys are not on the network. keys are in your wallet which is kept on your computer (preferably offline) and in order to keep them safe you don't need sharding. you just have to cut the access by keeping them isolated from attackers like having them in cold storage.

UnruffledST
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October 13, 2018, 04:20:30 PM
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i honestly have no idea where Private Key Sharding is used in cryptocurrency! if you know an actual case i would love to hear it.
but basically it is the Shamir's Secret Sharing[1] that you are talking about. the security behind it is from the math that is used to create the polynomial over the finite field.
there is no encryption or decryption in this case. you only have "shards" or parts of a secret that in a way you append to each other and then extrapolate to get the "secret".
take a look at this[2]. for example you have a private key that you split into 3 parts and store each part separately in different places.

the reason it is not used (to my knowledge) is exactly because you have to share the secrets and that is not desirable. in bitcoin what we have instead is multisignatures. which means you need multiple secrets instead of 1 that is split. and the benefit of it is that you don't have to share these secrets, you simply partly sign the transaction with your key and pass it along to other parties to partly-sign.

[1] https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing
[2] https://github.com/blockstack/secret-sharing

In a Distributed Network in order for a Private Key to not be compromised sharding will have to take place off the network, correct?
keys are not on the network. keys are in your wallet which is kept on your computer (preferably offline) and in order to keep them safe you don't need sharding. you just have to cut the access by keeping them isolated from attackers like having them in cold storage.

Thought I posted this but Fusion is taking a look at doing just so, also StorJ does the same thing shards are encrypted before being sent to the Network so in technicallity shards can be encrypted even though StorJ does not do this using Private Keys.
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October 13, 2018, 04:37:06 PM
Merited by pooya87 (1)
 #4

Thought I posted this but Fusion is taking a look at doing just so, also StorJ does the same thing shards are encrypted before being sent to the Network so in technicallity shards can be encrypted even though StorJ does not do this using Private Keys.

AFAIK in the case of StorJ the encrypted content is sharded, not the private keys themselves.


Come to think of it, let's check the whitepaper:

Files should be encrypted client-side before being sharded. The reference implementation uses AES256-CTR, but convergent encryption or any other desirable system could be implemented. This protects the content of the data from the storage provider, or farmer, housing the data. The data owner retains complete control over the encryption key, and thus over access to the data.

So yes, the private key stays with the content owner and should not touch the network. The content is encrypted before being published on the network, after which the network takes care of sharding the (encrypted) data.

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