Input consistency verification for server assisted secure function evaluation

A method for secure function evaluation (SFE) performed by a first of two parties that want to evaluate a function with assistance from a server, comprising:

• communicating with said server using an Oblivious Transfer (OT) protocol to obtain a wire secret that is an encrypted version of an input of said first party;
• providing said wire secret that is an encrypted version of an input of said first party to said second party;
• receiving an encrypted wire secret of said second party;
• receiving a garbled circuit corresponding to said function from said server for computation of an output;
• and wherein a predefined bit of the 0-secret of wire i in said garbled circuit is set to a random bit bi and a predefined bit of the 1-secret of wire i in said garbled circuit is set to bi;
• and
• storing one of said predefined bit of the 0-secret of wire i and said predefined bit of the 1-secret of wire i of the second party, and wherein said first party can verify input consistency by said second party over at least two executions by comparing stored values for said at least two executions with the corresponding values obtained from said server.

A system for secure function evaluation (SFE) performed by a server for two parties that want to evaluate a function, comprising:

• a memory;
• and
• at least one hardware device, coupled to the memory, operative to:
• compute garbled circuit corresponding to said function and wherein a predefined bit of the 0-secret of wire i in said garbled circuit is set to a random bit bi and a predefined bit of the 1-secret of wire i in said garbled circuit is set to bi;
• communicate with each of said parties using an Oblivious Transfer (OT) protocol to provide wire secrets that are encrypted versions of the respective inputs of each party, wherein each party provides said wire secret that is an encrypted version of an input of said party to the other of said party;
• and
• send the computed garbled circuit to each party for computation of a respective output;
• and wherein each party stores one of said predefined bit of the 0-secret of wire i and said predefined bit of the 1-secret of wire i of the other party, and wherein a given party can verify input consistency by the other party over at least two executions by comparing values stored by said given party for said at least two executions with corresponding values obtained from said server.

A system for secure function evaluation (SFE) performed by a first of two parties that want to evaluate a function with assistance from a server, comprising:

• a memory;
• and
• at least one hardware device, coupled to the memory, operative to:
• communicate with said server using an Oblivious Transfer (OT) protocol to obtain a wire secret that is an encrypted version of an input of said first party;
• provide said wire secret that is an encrypted version of an input of said first party to said second party;
• receive an encrypted wire secret of said second party;
• receive a garbled circuit corresponding to said function from said server for computation of an output;
• and wherein a predefined bit of the 0-secret of wire i in said garbled circuit is set to a random bit bi and a predefined bit of the 1-secret of wire i in said garbled circuit is set to bi;
• and
• store one of said predefined bit of the 0-secret of wire i and said predefined bit of the 1-secret of wire i of the second party, and wherein said first party can verify input consistency by said second party over at least two executions by comparing stored values for said at least two executions with the corresponding values obtained from said server.