75 results about "Block size" patented technology

A method of optimizing the size of blocks of coded data, intended to be subjected to iterative decoding, the method comprising a first step of evaluating a resource (T) available for the decoding of a block of normal size (N) and a second step of seeking, amongst a plurality of block sizes (N / k) which are submultiples of the normal size by an integer factor (k) greater than or equal to 1 and requiring on average a number of iterations ({overscore (n)}iterations(k)) compatible with the said available resource, the one which makes it possible to obtain the lowest error rate at the output of the iterative decoding.

Conventional block ciphers that traffic in 128-bit block sizes are ill-suited for operating in small domains like credit card numbers. Some embodiments relate to techniques for constructing and speeding up practical and provably secure schemes for deterministically enciphering data from a small domain like credit card numbers using a conventional block cipher or other pseudorandom function.

The invention discloses a white box block cipher construction method and system based on a FeistelBox structure. The method comprises: inputting n-bit plaintext, setting a block size n a , the number of iterative processing rounds r of the FeistelBox structure, use the T function to perform bit conversion, and convert the input n a bit bit to n b bit bit output, where n a +n b =n; add affine transformation between the rounds of the iterative processing rounds, and perform chain connection, the operation of each round is closely connected with the operation of the previous round and the next round, by converting the affine of the previous round The inverse transformation of the transformation is embedded in the lookup table operation of this round, and then the affine transformation of the previous round is applied to the result of the lookup table, and the affine transformation layer adopts the reversible affine transformation matrix; the encryption operation of S1-S2 is performed to obtain Encryption result; the system includes a bit conversion module, an affine transformation module and an execution operation module. The invention makes it impossible for the attacker to obtain the information of the ciphertext, increases the difficulty for the attacker to crack the password, and strengthens the security of key storage.

The present disclosure provides a method and device for preventing blockchain forks. The method includes: selecting s consecutive blocks B n to B n+s ; created by block B n Node A n Generate for block B n key pair; node A n Continuously generate block B in the blockchain n+1 to B n+s remain active during the process until block B in consecutive s blocks n+s Become an immutable block; in response to block B in consecutive s blocks n+s Become an immutable block, use the private key PK' n for block B n+s Signing; Response to block chain subsequent generation of block B m , put the signature in block B m in; by creating s blocks B n to B n+s The nodes of each block in the block perform the above steps, thereby forming multiple backward links related to the block size of the blockchain; the newly added nodes used to create new blocks judge the area according to the number of backward links Whether the block chain is forked.