Which method is commonly used to ensure integrity in encryption?

Hashing is a widely recognized method employed to ensure data integrity, especially in the context of encryption. When data is hashed, it is transformed into a fixed-length string of characters that is unique to the input data. Any alteration to the data—no matter how minor—will produce a distinct hash value. This property allows for the detection of changes or tampering, as the original and altered data will yield different hashes, clearly indicating that integrity has been compromised.

In scenarios requiring data integrity, hashing is often used alongside encryption. For example, a message can be hashed to create a digest, and then both the message and the hash can be encrypted to ensure both confidentiality and integrity. This combination provides assurance that the content has not been altered in transit.

The other methods listed have different primary purposes. Asymmetric and symmetric encryption focus on securing data through confidentiality rather than ensuring integrity. Public Key Infrastructure (PKI) involves the use of cryptographic keys and certificates to manage and authenticate the issuance of digital certificates, rather than directly focusing on integrity measures like hashing does. Thus, hashing stands out as the correct method to ensure integrity in the context of encryption.