In some papers, server generates keys for users as follows: $$sk_i=msk+H(ID_i)v_i\ (mod \ p)$$ where $msk=$ the secret key of server
$v_i$ is randomly selected from $Z_p$ for i-th user , $p$ is a prime number
$ID_i=$ the identity of i-th user
$sk_i=$ the secret key for i-thuser
$H$ is the hash function
If there is a user who knows more than one secret key, does that key generation scheme prevent to reveal the value of $msk$ from users.
How to prove the security?
I have forgotten paper references. Sorry for that.