Signature verification system, signature verification method, and program
AssigneeNEC Corporation
InventorsBatnyam Enkhtaivan, Hiroto Tamiya, Toshiyuki Isshiki
Life of this patent
Estimating the term…
Abstract
A signature verification system 100 includes a signature apparatus 210 configured to sign data including a predetermined data block replaced with a chameleon hash value, using one or more public keys for changers authorized to change data, a changing apparatus 310 configured to receive the signed data, and to change a content of the predetermined data block of the signed data using a private key associated with any of the one or more public keys, and a verifying apparatus 410 configured to receive the signed data with the changed content of the predetermined data block, and to verify the signature using the one or more public keys for the changers.
Claims7
A signature verification system comprising:
- a signature apparatus comprising a memory storing instructions and one or more processors configured to execute the instructions to sign data including a predetermined data block using one or more public keys for changers authorized to change data, the predetermined data block is authorized to be changed and is replaced with a chameleon hash value;
- one or more changing apparatuses comprising a memory storing instructions and one or more processors configured to execute the instructions to receive the signed data, and to change a content of the predetermined data block of the signed data using a private key associated with any of the one or more public keys;
- and
- a verifying apparatus comprising a memory storing instructions and one or more processors configured to execute the instructions to receive the signed data with the changed content of the predetermined data block and to verify the signature using the one or more public keys for the changers,
- the chameleon hash value is calculated according to a chameleon hash function CH expressed by Expression (3) below by using a message m indicating the data and a random number r,
- [
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- .
- 1
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-
- CH
- p
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- p
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- m
-
- p
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- m
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- …
-
- p
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- m
- =
- g
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-
- p
-
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- 1
- m
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- k
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- m
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-
- z
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- m
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-
- p
-
- k
- n
- m
- =
- CH
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- k
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- p
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- (
- 3
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- where x denotes a private key for a changer, y denotes a public key for the changer, and y=gx mod p.
A signature verification method comprising:
- a signature step of signing data including a predetermined data block using one or more public keys for changers authorized to change data, the predetermined data block is authorized to be changed and is replaced with a chameleon hash value;
- a changing step of receiving the signed data, and changing a content of the predetermined data block of the signed data using a private key associated with any of the one or more public keys;
- and
- a verifying step of receiving the signed data with the changed content of the predetermined data block, and verifying the signature using the one or more public keys for the changers,
- the chameleon hash value is calculated according to a chameleon hash function CH expressed by Expression (3) below by using a message m indicating the data and a random number r,
- [
- Math
- .
- 1
- ]
-
- CH
- p
-
- k
- 1
- ,
- p
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- k
- 2
- ,
- …
- ,
- p
-
- k
- n
- (
- m
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- r
- )
- =
- g
- r
-
- p
-
- k
- 1
- m
-
- p
-
- k
- 2
- m
-
- …
-
- p
-
- k
- n
- m
- =
- g
- r
- ′
-
- p
-
- k
- 1
- m
-
- p
-
- k
- 2
- m
-
- …
-
- z
- j
- m
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-
- ⋯
-
- p
-
- k
- n
- m
- =
- CH
- p
-
- k
- 1
- ,
- …
- ,
- p
-
- k
- j
- →
- z
- j
- ,
- …
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- p
-
- k
- n
- (
- m
- →
- m
- ′
- ,
- r
- ′
- )
- (
- 3
- )
- where x denotes a private key for a changer, y denotes a public key for the changer, and y=gx mod p.
Dependencies are inferred from the claim text.