A form of digital signature where the signer is not privy to the content of the message is called a:

A.
Encrypted signature

B.
Zero knowledge proof

C.
Masked signature

D.
Blind signature

Explanation:
A blind signature algorithm for the message M uses a blinding factor, f; a modulus m; the private
key, s, of the signer and the public key, q, of the signer. The sender, who generates f and knows q,
presents the message to the signer in the form: Mf q (mod m) Thus, the message is not in a form

readable by the signer since the signer does not know f. The signer signs Mf q (mod m) with his/her
private key, returning (Mf q)s (mod m) This factor can be reduced to fMs (mod m) since s and q are
inverses of each other. The sender then divides fMs (mod m) by the blinding factor, f, to obtain Ms
(mod m) Ms (mod m) is, therefore, the message, M, signed with the private key, s, of the signer.
Answer Zero knowledge proof refers to a zero knowledge proof. In general, a zero knowledge proof
involves a person, A, trying to prove that he/she knows something, S, to another person, B, without
revealing S or anything about S. Answers Masked signature and Encrypted signature are distracters.