Method and system for re-encryption of encrypted data by generating re-encryption key
This disclosure relates generally to a method and system for re-encryption of an encrypted data. State-of-the-art methods provide the re-encryption scheme for a specific Fully Homomorphic Encryption (FHE) encrypted data. However, a generic scheme that converts any given FHE scheme to an HPRE scheme is not yet achieved. The disclosed method provides re-encryption of the encrypted data transferred between a first user and a second user by a re-encryption key. The re-encryption key is obtained by splitting a private key of the first user into a primary private key and a secondary private key. The primary private key generates a public re-key component using probabilistic encryption algorithm; and the secondary private key generates a private re-key component using probabilistic switch key generation algorithm. Both the private re-key and the public re-key are consolidated further to generate the re-encryption key.
1 . A method of re-encrypting the encrypted data, the method comprising:
receiving, via one or more hardware processors, a request to securely transfer data from a first user to a second user wherein the first user holds a first public-private key pair, and the second user holds a second public-private key pair;
generating, via the one or more hardware processors, a ciphertext from a plaintext associated with the data of the first user using a public key from the first public-private key pair and a plurality of public parameters using a probabilistic encryption algorithm;
re-encrypting, via the one or more hardware processors, the ciphertext using a re-encryption key, to obtain a re-encrypted ciphertext, wherein generating the re-encryption key comprises:
obtaining a private re-key component by splitting a private key of the first public-private key pair into a primary private key part and a secondary private key part;
providing, the secondary private key part to the probabilistic switch key generation algorithm to obtain the private re-key component; and
obtaining a public re-key component by providing the primary private key part to the probabilistic encryption algorithm along with a public key of the second public-private key pair to obtain the public re-key component;
consolidating the private re-key component and the public re-key component using a probabilistic rekey generation algorithm to obtain the re-encryption key; and
transferring, via the one or more hardware processors, the re-encrypted ciphertext without the re-encryption key, wherein the second user decrypts the re-encrypted ciphertext using private key of the second public-private key pair.
2 . The method as claimed in claim 1 , wherein the probabilistic re-encryption algorithm is executed on a proxy server for re-encryption.
3 . The method as claimed in claim 1 , wherein the homomorphic evaluations performed by the first user or the second user on the ciphertext and the re-encrypted ciphertext comprises multiplication and addition.
4 . The method as claimed in claim 1 , wherein the encrypted ciphertext and the re-encrypted ciphertext are evaluated through FHE schemes wherein the FHE schemes are selected from Fast Fully Homomorphic Encryption (TFHE), Brakerski-Gentry-Vaikuntanathan (BGV), Brakerski/Fan-Vercauteren (BFV), Cheon-Kim-Kim-Song (CKKS), Ducas-Micciancio (DM) and Chillotti-Gama-Georgieva-Izabachene (CGGI).
5 . A system, comprising:
a memory storing instructions;
one or more communication interfaces; and
one or more hardware processors coupled to the memory via the one or more communication interfaces, wherein the one or more hardware processors are configured by the instructions to:
receive a request to securely transfer data from a first user connected to the system via a first user machine to a second user connected to the system via a second user machine, wherein the first user holds a first public-private key pair, and the second user holds a second public-private key pair;
generate a ciphertext from a plaintext associated with the data of the first user using a public key from the first public-private key pair and a plurality of public parameters using a probabilistic encryption algorithm;
re-encrypt the ciphertext using a re-encryption key, to obtain a re-encrypted ciphertext, wherein generating the re-encryption key comprises:
obtaining a private re-key component by splitting a private key of the first public-private key pair into a primary private key part and a secondary private key part;
providing, the secondary private key part to the probabilistic switch key generation algorithm to obtain the private re-key component; and
obtaining a public re-key component by providing the primary private key part to the probabilistic encryption algorithm along with a public key of the second public-private key pair to obtain the public re-key component;
consolidate the private re-key component and the public re-key component using a probabilistic rekey generation algorithm to obtain the re-encryption key; and
transfer the re-encrypted ciphertext without the re-encryption key, wherein the second user decrypts the re-encrypted ciphertext using private key of the second public-private key pair.
6 . The system as claimed in claim 5 , wherein the probabilistic re-encryption algorithm is executed on a proxy server machine for re-encryption.
7 . The system as claimed in claim 5 , wherein the homomorphic evaluations performed by the first user or the second user on the ciphertext and the re-encrypted ciphertext comprises multiplication and addition.
8 . The system as claimed in claim 5 , wherein the encrypted ciphertext and the re-encrypted ciphertext are evaluated through FHE schemes wherein the FHE schemes are selected from Fast Fully Homomorphic Encryption (TFHE), Brakerski-Gentry-Vaikuntanathan (BGV), Brakerski/Fan-Vercauteren (BFV), Cheon-Kim-Kim-Song (CKKS), Ducas-Micciancio (DM) and Chillotti-Gama-Georgieva-Izabachene (CGGI).
9 . One or more non-transitory machine-readable information storage mediums comprising one or more instructions which when executed by one or more hardware processors cause:
receiving a request to securely transfer data from a first user to a second user wherein the first user holds a first public-private key pair, and the second user holds a second public-private key pair;
generating a ciphertext from a plaintext associated with the data of the first user using a public key from the first public-private key pair and a plurality of public parameters using a probabilistic encryption algorithm;
re-encrypting the ciphertext using a re-encryption key, to obtain a re-encrypted ciphertext wherein, generating the re-encryption key comprises:
obtaining a private re-key component by splitting a private key of the first public-private key pair into a primary private key part and a secondary private key part;
providing, the secondary private key part to the probabilistic switch key generation algorithm to obtain the private re-key component; and
obtaining a public re-key component by providing the primary private key part to the probabilistic encryption algorithm along with a public key of the second public-private key pair to obtain the public re-key component;
consolidating the private re-key component and the public re-key component using a probabilistic rekey generation algorithm to obtain the re-encryption key; and
transferring the re-encrypted ciphertext without the re-encryption key, wherein the second user decrypts the re-encrypted ciphertext using private key of the second public-private key pair.
10 . The one or more non-transitory machine-readable information storage mediums of claim 9 , wherein the probabilistic re-encryption algorithm is executed on a proxy server for re-encryption.
11 . The one or more non-transitory machine-readable information storage mediums of claim 9 , wherein the homomorphic evaluations performed by the first user or the second user on the ciphertext and the re-encrypted ciphertext comprises multiplication and addition.
12 . The one or more non-transitory machine-readable information storage mediums of claim 9 , wherein the encrypted ciphertext and the re-encrypted ciphertext are evaluated through FHE schemes wherein the FHE schemes are selected from Fast Fully Homomorphic Encryption (TFHE), Brakerski-Gentry-Vaikuntanathan (BGV), Brakerski/Fan-Vercauteren (BFV), Cheon-Kim-Kim-Song (CKKS), Ducas-Micciancio (DM) and Chillotti-Gama-Georgieva-Izabachene (CGGI).