A method for generating a random number is used for a plurality of blocks in a blockchain. The method comprises the steps of: selecting a committee comprising a subset of nodes from the blockchain; executing a distributed key generation to generate a share key and a public key at each of the nodes, wherein the public key further comprises a set of verification keys; broadcasting a share signature from each of the nodes; executing a threshold signature at each of the nodes when a new block is generated; and executing a random number which is a hash value of the threshold signature which is combined from a plurality of partial signature generated from the nodes.

Biometric data such as iris, facial, or fingerprint data may be obtained from a user. A public code may be generated from the biometric data, but does not obtain any of the biometric data or information that can be used to identify the user. The public code includes information that can be used to extract from the biometric data a biometric code that is suitable for bitwise comparison. Neither the underlying biometric data nor information from which the biometric data may be determined is stored as only the public code and the actual biometric feature of the user is required to generate the biometric code.

A computer-implemented method includes: obtaining, by a data party, a piece of plaintext to be encrypted; generating a ciphertext file including multiple pieces of ciphertext, each piece of ciphertext being derived from a homomorphic encryption algorithm executed on the piece of plaintext; adding a first file identifier of the ciphertext file to a file identifier set corresponding to the piece of plaintext; and in response to a piece of ciphertext derived from the piece of plaintext being needed for a cooperative calculation in which the data party is participating: obtaining the first file identifier from the file identifier set corresponding to the piece of plaintext, reading a first piece of ciphertext from the ciphertext file identified by the first file identifier, and sending the first piece of ciphertext to a partner participating in the cooperative calculation.

Embodiments of the present disclosure relate to copy protection. A request to copy a file from a requestor with one or more privileges sufficient to access the file may be received. The file may be determined to be subject to copy protection. In response to determining that the file is subject to copy protection, a notification of the copy attempt may be transmitted. Copy protection may then be applied to the file.

A transmitter encodes information with randomly flipped bits. A cipher key that includes for each letter of an alphabet a unique string of binary bits of length N and a total amount of bits M to be randomly flipped where M<N are stored using a secure memory. An information message that includes a series of one or more letters is received using a transmitter. The cipher key is read from the secure memory and at least one letter of the series is converted to a corresponding unique string of binary bits of length N. The total amount of bits M to flip are read from the secure memory, the M bits of the unique string are randomly selected, and the M bits are flipped to the opposite binary value. The string with M flipped bits is transmitted through a communications channel.

A computer-implemented method comprises: committing a transaction amount t of a transaction with a commitment scheme to obtain a transaction commitment value T, the commitment scheme comprising at least a transaction blinding factor r_t; encrypting a combination of the transaction blinding factor r_t and the transaction amount t with a public key PK_B of a recipient of the transaction; and transmitting the transaction commitment value T and the encrypted combination to a recipient node associated with the recipient for the recipient node to verify the transaction.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for secure data transmission using natural language. One of the methods includes: obtaining sensitive information for a user; obtaining a natural language key for the user, wherein the natural language key for the user includes one or more natural language tokens; generating decoding data for the sensitive information for the user, wherein generating the decoding data comprises: for each place in the sensitive information for the user: assigning a respective one of the natural language tokens in the natural language key for the user to the value at the place, and generating one or more respective dummy natural language tokens for each value of the respective set of possible values for the place other than the value at the place; and providing the decoding data for use in decoding the natural language key into the sensitive information.

An attack on an RSA encryption algorithm based on simple power analysis (SPA) is thwarted by scrambling the sliding window sequence that results from performing sliding window processing on a power exponent. The sliding window sequence is scrambled with a random code that is utilized to determine an adjustment tendency and an adjustment length.

Input signals may be received. Furthermore, a control signal controlling the implementation of a Differential Power Analysis (DPA) countermeasure may be received. One of the input signals may be transmitted as an output signal based on the control signal. A cryptographic operation may be performed based on the first output signal that is transmitted based on the control signal.

The present invention provides an improved system and method for using cryptography to secure computer-implemented choice mechanisms. In several preferred embodiments, a process is provided for securing participants' submissions while simultaneously providing the capability of validating their submissions. This is referred to as a random permutation. In several other preferred embodiments, a process is provided for securing participants' advance instructions while simultaneously providing the capability of validating their advance instructions. This is referred to as a secure advance instruction. Applications include voting mechanisms, school choice mechanisms, and auction mechanisms.