Final answer:
In PKI, the term that refers to a public key used to verify the certificate used in a digital signature is trust anchor. It is a public key that is considered inherently trustworthy and serves as the starting point for verifying the authenticity of a certificate chain.
Step-by-step explanation:
In PKI, the term that refers to a public key used to verify the certificate used in a digital signature is trust anchor. A trust anchor is a public key that is considered to be inherently trustworthy by relying parties. It serves as the starting point for verifying the authenticity of a certificate chain.
When a digital signature is created, it is encrypted with the private key of the issuer, and it can be decrypted and verified using the corresponding public key of the issuer. However, relying parties do not directly trust the issuer's public key. Instead, they trust the public key of a trusted authority, which is known as the trust anchor. This trust anchor is usually distributed with the software or operating system and is used to verify the trustworthiness of the entire certificate chain.
For example, let's say Alice wants to verify the digital signature of a document that was signed by Bob. Bob's certificate contains his public key, which Alice can use to verify the digital signature. However, Alice does not directly trust Bob's public key. Instead, Alice trusts the public key of a trusted authority, such as a certificate authority (CA), which serves as the trust anchor. Alice can use the trust anchor's public key to verify the authenticity and integrity of Bob's certificate and, in turn, verify the digital signature.