Question

(a) Who issues the certificate?

(b) Who is the owner of the certificate?
(c) Who generated the signature on this certificate, and how can this signature be verified?
(d) The public key contained in this certificate is based on the RSA algorithm. Using
the RSA algorithm, to encrypt a message M, we calculate Me mod n. What is
the value of e and n in this public key? If a number is too large, you only need to
write down its first four bytes.
(e) Before issuing the certificate, the CA needs to do a verification regarding the subject
field. Please describe what this verification is, and why it is necessary.

Answer 1

Digital certificates are issued by a Certificate Authority (CA) to verified entities. The CA's signature on a certificate can be verified with its public key. In RSA-based certificates, 'e' and 'n' are part of the public key and are crucial for encryption and signature verification.

Step-by-step explanation:

The question relates to digital certificates used in computer security, particularly those used in public key infrastructure (PKI). Here is a concise answer to each sub-question:

1. Issuing authority of the certificate: Digital certificates are issued by a Certificate Authority (CA), which is a trusted entity in the field of computer security. The CA validates the identity of the certificate requester before issuing the certificate.
2. Owner of the certificate: The certificate owner is the entity or individual whose identity has been verified and to whom the certificate has been issued.
3. Signature generation: The signature on the certificate is generated by the CA using its private key. This signature can be verified by anyone who has the CA's public key by ensuring the signed data, when decrypted with the public key, matches the original data.
4. Value of e and n in the RSA public key: The value of e and n are part of the public key details contained in the certificate. These values are used in the RSA encryption and signature verification processes. Specific values for e and n are not provided in the question, but generally, e is a public exponent, and n is the modulus (a product of two large primes).
5. Subject field verification: The CA verifies the information in the subject field of the certificate request to ensure that the applicant is who they claim to be. This process is crucial to maintain trust in the PKI ecosystem and to prevent malicious entities from obtaining certificates under pretenses.