In Distributed Key Generation(DKG), why is there a need to actually create a master secret which can then derive into a single public and private keypair(for signatures) and a secret key(encryption)?

I would like experts here to explain to me (explain in a layman's way) because it seems to me that having a master secret to both encrypt/decrypt and signs messages are not that recommended in terms of security?

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    $\begingroup$ What's DKG? I'm not aware of any secure system where it's meaningful to use the same key for encrypting as for signing. Encrypting almost always uses a symmetric (shared secret) key, signing always (by definition) uses (the private key of) an asymmetric key pair. Those usually have very different structure, e.g. trying to use an AES-256 key for RSASSA-PSS signing is about as practical as trying to use a herring to cut down the largest tree in a forest! $\endgroup$ Apr 11, 2022 at 14:12
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    $\begingroup$ @SAIPeregrinus sorry for not telling what DKG is but i stumble across the articles that DKG was used primarily in blockchain. Maybe DKG has changed as time progresses, my question lies in the sharing or creating a master secret. What's the exact purpose to create a master secret that all nodes has access to? The master secret can either be use in encryption or signing purposes (master signature keypair/ master symmetric key). $\endgroup$
    – Hern
    Apr 11, 2022 at 14:39
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    $\begingroup$ Because in my humble opinion.., i just feels like everyone group together to create a master secret in a network like blockchain seems to be against "trustless". It brings questions like .... can we trust all the nodes to not sign the messages without proper permissions and if all nodes can encrypt/decrypt using one master secret isn't it literally the same as any centralized key management system or cloud encryption? $\endgroup$
    – Hern
    Apr 11, 2022 at 14:41
  • $\begingroup$ The master secret can never actually be derived by one party in DKG. The shares are used in a distributed way to perform signatures. $\endgroup$
    – fraiser
    May 11, 2022 at 22:03
  • $\begingroup$ To understand DKG, what're the prerequisites or books that I need to know/read given that I have zero or little understanding on cryptography. $\endgroup$
    – Hern
    Sep 1, 2022 at 11:53


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