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US 2011/0216900 A1Published application
Methods of encryption and decryption and encryption systems using the same
AssigneeSamsung Electronics Co., Ltd.
InventorsJoongChul Yoon, Seokhie Hong, Taehyun Kim, Heeseok Kim
Life of this patent
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Abstract
Provided is a decryption method of an encryption algorithm. In the decryption method, a secret key can be received. A plurality of Montgomery multiplications can be repeated on a cipher text until a modular exponentiation of the secret key. When the repeated Montgomery multiplications are performed, an order of the plurality of Montgomery multiplications or an order of operands can be arbitrarily changed.
Claims20
A decryption method, comprising:
- receiving a secret key;
- and
- repeating a plurality of Montgomery multiplications on a cipher text until a modular exponentiation of the secret key,
- wherein, when the repeated Montgomery multiplications are performed, an order of the plurality of Montgomery multiplications or an order of operands is arbitrarily changed.
1 more element
An encryption system comprising:
- an encryption unit encrypting a plaintext using an encryption key according to an encryption process;
- and
- a decryption unit decrypting a ciphertext using a decryption key according to the encryption process,
- wherein the encryption process repeats a plurality of Montgomery multiplications using first and second operands according to a binary value bit of the encryption key on the ciphertext until a modular exponentiation of the encryption key, or repeats a plurality of Montgomery multiplications using the first and second operands according to a binary value bit of the decryption key on the plaintext until a modular exponentiation of the decryption key, and an order of the Montgomery multiplications or an order of the first and second operands is arbitrarily changed.
1 more element
A decryption unit comprising:
- a shift register receiving a secret key comprising a plurality of bits and sequentially outputting the plurality of binary value bits of the secret key;
- a random generator generating a first random number for blinding and a second random number for arbitrarily changing an order of Montgomery multiplications and an order of operands;
- an exponentiation operator performing a modular exponentiation of the first random number on a first fixed value and a second fixed value that are inputted to blind a ciphertext, respectively, the second fixed value being an inverse element of 2m modular exponentiated value of the first fixed value;
- a first operand register storing a first operand, the first operand having an initial value being a result value of a Montgomery multiplication of the first fixed value and a square of a radix;
- a second operand register storing a second operand, the second operand having an initial value being a result value of a Montgomery multiplication of the initial value of the first operand and a result value of Montgomery multiplication of the ciphertext and the square of the radix;
- a third operand register storing the second fixed value for removing the blinding of the ciphertext;
- and
- a Montgomery multiplier performing a plurality of Montgomery multiplications using the first and second operands according to a binary value bit outputted from the shift register, the first and second operands being changed upon the plurality of Montgomery multiplications, and the order of the Montgomery multiplications or the order of the first and second operands being changed according to the second random number when the Montgomery multiplications are performed.
5 more elements
Dependencies are inferred from the claim text.