Bugzilla

https://www.ietf.org/archive/id/draft-irtf-cfrg-rsa-blind-signatures-12.html

RSA Blind signatures. 

Blind signatures is a form of signatures where the content of the signature is hidden. When the server signs a data, this data is indistinguishable from random, thus not leaking the user information. 

One of the examples of Blinded Signatures is described in https://www.ietf.org/archive/id/draft-irtf-cfrg-rsa-blind-signatures-12.html. 
"Upon completion of this protocol, the server learns nothing, whereas the client learns sig. In particular, this means the server learns nothing of msg or input_msg and the client learns nothing of skS."

RSA Blind signatures. 

Blind signatures is a form of signatures where the content of the signature is hidden. When the server signs a data, this data is indistinguishable from random, thus not leaking the user information. 

One of the examples of Blinded Signatures is described in https://www.ietf.org/archive/id/draft-irtf-cfrg-rsa-blind-signatures-12.html. 
It's using RSA for blinding. 
The desired property is : "Upon completion of this protocol, the server learns nothing, whereas the client learns sig. In particular, this means the server learns nothing of msg or input_msg and the client learns nothing of skS."

Thus, this primitive is extremely important in the cases when the client wants to sign a data without revealing it.