Conversion key generation apparatus, encrypted text conversion apparatus, decryption apparatus, encrypted text conversion system, conversion key generation method, encrypted text conversion method, decryption method, and program
AssigneeNippon Telegraph and Telephone Corporation
InventorRyo NISHIMAKI
Life of this patent
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Abstract
A transformation key generation apparatus has key generation means for receiving a decryption key sks of a first public key encryption scheme Σs and a public key pkd of a second public key encryption scheme Σd, and generating a transformation key utks→d for transforming first ciphertext cts of the first public key encryption scheme Σs into second ciphertext tct of the second public key encryption scheme Σd by using a probabilistic circuit or function secret sharing.
Claims10
A transformation key generation apparatus comprising:
- a processor;
- and
- a memory storing program instructions that cause the processor to receive a decryption key of a first public key encryption scheme and a public key of a second public key encryption scheme, and generate a transformation key for transforming first ciphertext of the first public key encryption scheme into second ciphertext of the second public key encryption scheme by using a probabilistic circuit or function secret sharing.
A ciphertext transformation apparatus comprising:
- a processor;
- and
- a memory storing program instructions that cause the processor to receive a transformation key for transforming first ciphertext of a first public key encryption scheme into second ciphertext of a second public key encryption scheme and the first ciphertext, and transform the first ciphertext into the second ciphertext by using a probabilistic circuit or function secret sharing.
A decryption apparatus comprising:
- a processor;
- and
- a memory storing program instructions that cause the processor to receive second ciphertext obtained by transforming first ciphertext of a first public key encryption scheme with a transformation key and a decryption key of a second public key encryption scheme, and output a message obtained by decrypting the second ciphertext with the decryption key.
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Dependencies are inferred from the claim text.