A digital certificate usually contains an identity, a public key, and signatures of the issuer attesting that the public key belongs to the identity. Other fields that may be present include the certificate issuer's name (e.g. university, company, or government), signature algorithms, and the validity period of the certificate. A. What security purpose these other fields serve, if any? Explain your answer. B. Assume that the hash (message digest) of the digital certificate is signed by the certificate authority. What is the impact on the validity of the digital certificate if: The hash algorithm is not collision resistant? Justify your answer. The private key of the certificate authority is compromised? Justify your answer. Why does the Public Key Infrastructure (PKI) need a means to cancel or invalidate certificates? Why is it not sufficient for the PKI to stop distributing a certificate after is becomes invalid? A digital certificate usually contains an identity, a public key, and signatures of the issuer attesting that the public key belongs to the identity. Other fields that may be present include the certificate issuer's name (e.g. university, company, or government), signature algorithms, and the validity period of the certificate. A. What security purpose these other fields serve, if any? Explain your answer. B. Assume that the hash (message digest) of the digital certificate is signed by the certificate authority. What is the impact on the validity of the digital certificate if: The hash algorithm is not collision resistant? Justify your answer. The private key of the certificate authority is compromised? Justify your answer. Why does the Public Key Infrastructure (PKI) need a means to cancel or invalidate certificates? Why is it not sufficient for the PKI to stop distributing a certificate after is becomes invalid