Carry-lookahead adder, secure adder and method for performing carry-lookahead addition

A secure adder, comprising:

• a mask generator, comprising:
• a random number generator configured to randomly generate a first mask value, a second mask value and a third mask value;
• and
• a first mask unit configured to perform a first mask operation on first data with the first mask value to obtain first masked data, and to perform a second mask operation on second data with the second mask value to obtain second masked data, wherein the first mask value is different from the second mask value;
• and
• a carry-lookahead adder, comprising:
• a second mask unit configured to perform a third mask operation on the first masked data with the second mask value to obtain third masked data;
• a third mask unit configured to perform a fourth mask operation on the second masked data with the first mask value to obtain fourth masked data:
• a first exclusive-OR (XOR) gate configured to receive the first mask value and the second mask value to provide a variable value;
• a half adder configured to receive the third masked data and the fourth masked data to generate a propagation value and an intermediate generation value:
• a fourth mask unit configured to perform a fifth mask operation on the propagation value with the third mask value to obtain fifth masked data;
• a logic circuit configured to provide a generation value according to the propagation value, the intermediate generation value and the variable value;
• a carry-lookahead generator configured to provide a carry output and a carry value according to a carry input, the generation value and the propagation value;
• and
• a second XOR gate configured to receive the fifth masked data and the carry value to provide a sum output.

A method for performing carry-lookahead addition, comprising:

• performing a first mask operation on first input data corresponding to a second mask value with a first mask value to obtain first masked data;
• performing a second mask operation on second input data corresponding to the first mask value with the second mask value to obtain second masked data, wherein the first mask value is different from the second mask value;
• obtaining a variable value according to the first mask value and the second mask value;
• using a half adder to obtain an intermediate generation value and a propagation value according to the first masked data and the second masked data;
• performing a third mask operation on the propagation value with a third mask value to obtain third masked data;
• obtaining a generation value according to the propagation value, the intermediate generation value and the variable value;
• using a carry-lookahead generator to obtain a carry output and a carry value according to a carry input, the generation value and the propagation value;
• and
• obtaining a sum output according to the third masked data and the carry value,
• wherein the first mask operation, the second mask operation and the third mask operation are performed by different exclusive-OR (XOR) gates.