Methods and Apparatus for Securely Classifying Data

A method of determining a most likely sequence for a given data set, the method comprising a computer system associated with a first party performing steps of:

• encrypting a model;
• sending the encrypted model to a second party such that the second party utilizes the encrypted model to determine cost values associated with a particular sequence of observed outputs associated with the given data set, obtaining from the second party the cost values;
• determining at least one index of a minimum cost value from the cost values obtained from the second party;
• sending the at least one index of the minimum cost value to the second party such that the second party determines, as the most likely sequence, a minimum cost sequence resulting from the at least one index.

A method of securely determining a minimum data value of a set of asymmetrically encrypted data values, the method comprising a computer system performing steps of:

• decrypting the values in the set of asymmetrically encrypted data values;
• comparing the values in the set of asymmetrically encrypted data values;
• and
• outputting an index of the minimum data value of the set of asymmetrically encrypted data values;
• wherein the set of asymmetrically encrypted data values comprises a public and private key pair, and numeric data values encrypted using the public key and transmitted to a holder of the private key.

Apparatus for determining a most likely sequence for a given data set, the apparatus being associated with a first party and comprising:

• a memory;
• and
• a processor coupled to the memory and configured to:
• obtain from a second party an encrypted model;
• utilize the encrypted model to determine cost values associated with a particular sequence of observed outputs associated with the given data set, send to the second party the cost values;
• obtain from the second party at least one index of a minimum cost value determined by the second party from the cost values sent thereto;
• and determine, as the most likely sequence, a minimum cost sequence resulting from the at least one index.