Samsung Electronics Co., Ltd.

Yoo-jin Baek

Ihor Vasyltsov

Hee-kwan Son

Saldamli Gokay

A circuit for converting Boolean and arithmetic masks includes 'm' converting units, wherein m is an integer greater than 1. Each of the m converting unit includes; a first converting unit configured to receive first bits of input data, output one of the first bits as a first output bit, perform an XOR operation with respect to at least part of the first bits, and output an XOR operation result as a first intermediate result bit to a next converting unit in a sequence of converting unit ranging between 2 and n&#x2212;1; and an nconverting unit, wherein n is an integer greater than or equal to 2 and less than or equal to m, configured to receive n&#x2212;1bits and nbits of the input data, and at least one of an n&#x2212;1intermediate result bit and n&#x2212;1output bit from an n&#x2212;1converting unit, perform an AND operation and the XOR operation with respect to a first group of the received bits, output an operation result for the first group as an noutput bit, perform the AND operation and the XOR operation with respect to a second group of the received bits, and output an operation result of the second group as an nintermediate result bit.

Circuit and method converting boolean and arithmetic masks

A method of countering side-channel attacks on an elliptic curve cryptosystem (ECC) is provided. The method comprises extending a definition field of an elliptic curve of the ECC to an extension ring in a first field; generating a temporary ciphertext in the extension ring and countering attacks on the ECC; and generating a final ciphertext for the first field if a fault injection attack on the ECC is not detected. The countering of attacks on the ECC may comprise countering a power attack on the ECC. Checking if there is a fault injection attack on the ECC may be performed by determining if the temporary ciphertext satisfies a second elliptic curve equation. The fault detection algorithms takes place in a small subring of the extension ring, not in the original field, to minimize the computational overhead. The method can improve the stability of the ECC and reduce computational overhead of the ECC.

Method of countering side-channel attacks on elliptic curve cryptosystem

Provided are a modular multiplication method with an improved arithmetic operation, a modular multiplier and a cryptograph calculating system having the modular multiplier. The modular multiplication method comprises performing a first arithmetic operation including a first multiplication on a first bit string of a multiplicand and a first bit string of a multiplier and a first reduction for eliminating partial bits of the first multiplication result, performing a second arithmetic operation including a second multiplication on a second bit string of the multiplicand and a second bit string of the multiplier and a second reduction for eliminating partial bits of the second multiplication result, and calculating a modular multiplication result using the result of the first arithmetic operation and the result of the second arithmetic result. The first arithmetic operation and the second arithmetic operation are independently performed.

Modular multiplication method, modular multiplier and cryptosystem having the same

A method and system for encrypting input data may include receiving an input point and a randomness rate and generating a random selection value and a random position value from the randomness rate. At least one of the input point and points encrypted by performing elliptic curve (EC) operation over a plurality of rounds may be randomly selected based on the randomness rate and the random position value. The selected point may be converted to a point representation directed by the random selection value. A finally encrypted output point may be generated by performing the EC operation over a plurality of rounds based on the input point and a secret key.

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Seongnam-si, South Korea

Yoo-jin Baek