The disclosed exemplary embodiments include computer-implemented apparatuses and methods that validate confidential data based privacy-preserving homomorphic computations involving encrypted data. For example, an apparatus may receive, from a first computing system, encrypted data that includes a first encrypted value representative of at least one of first account data or an element of cryptographic data. Based on the first encrypted value and on second encrypted values, the apparatus may generate encrypted residual values representative of second account data associated with one or more reference accounts, and the apparatus may request and receive a decrypted residual value associated with each of the encrypted residual values from a second computing system. The apparatus may transmit the decrypted residual values to the first computing system, which may validate the first account data based on at least the decrypted residual values and perform operations associated with the validated first account data.