Private categorization using shared keys

A method implements private categorization using shared keys. The method includes selecting an encryption key, encrypting a transaction vector, generated from a transaction record, with the encryption key to generate an encrypted transaction vector, and receiving an encrypted category vector generated by a classifier model, corresponding to the encryption key, from the encrypted transaction vector. The method further includes decrypting a category from the encrypted category vector with a decryption key corresponding to the encryption key and presenting the category.