Which of the following is the definition of registration authority ( ra)?

a. the process of applying an algorithm to cleartext (or plain text) data, resulting in a ciphertext.
b. the certificate authority’s list of invalid certificates.
c. the concept of ensuring that an originator cannot refute the validity of a statement or document.
d. an entity that is responsible for the registration and initial authentication of certificate subscribers.

The correct answer following question will be Option D.

Explanation:

An authority that verifies the user requests for digital certificates and tells to the CA (Certificate authority) to issue the certificates, known as Registration Authority (RA). The digital certificate contains a key named "public key" which is used to encrypt and decrypt digital signatures.

Hence, registration authority, it's an entity that is responsible for the authentication of certificate and registration and the other given options are not relatable to this authority.

So, option D is the correct answer.

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