Quantum key distribution-based quantum digital signature method and system including trusted node
The present disclosure according to at least one embodiment provides a quantum key distribution (QKD)-based quantum digital signature method using a trusted node, the QKD-based quantum digital signature method being performed by a trusted node. The method comprises sharing a first secret key with a message-sending node, sharing a second secret key with a message-receiving node, generating a first trusted-node signature by performing a partial QKD process together with the message-sending node, generating a second trusted-node signature by performing a partial QKD process together with the message-receiving node, and verifying a first message with the shared first and second secret keys and with the first and second trusted-node signatures.
1 . A quantum key distribution (QKD)-based quantum digital signature method using a trusted node, the QKD-based quantum digital signature method being performed by the trusted node and comprising:
sharing a first secret key with a message-sending node;
sharing a second secret key with a message-receiving node;
generating a first trusted-node signature by performing a partial QKD process together with the message-sending node;
generating a second trusted-node signature by performing a partial QKD process together with the message-receiving node; and
verifying a first message with the shared first and second secret keys and with the first and second trusted-node signatures,
wherein
the first trusted-node signature is a trusted-node bitstring having a first length,
the second trusted-node signature is a trusted-node bitstring having a second length, and
a difference between the first length and the second length is determined based on a loss rate of a quantum channel between the trusted node and the message-sending node.
2 . The QKD-based quantum digital signature method of claim 1 , wherein
the sharing the first secret key, comprises sharing a bitstring having a third length with the message-sending node via a QKD process,
the sharing the second secret key, comprises sharing a bitstring having a fourth length with the message-receiving node via a QKD process,
the first secret key is extracted from the bitstring having the third length, and
the second secret key is extracted from the bitstring having the fourth length.
3 . The QKD-based quantum digital signature method of claim 2 , wherein the bitstrings having the third and fourth lengths are determined based on the loss rate of the quantum channel between the trusted node and the message-sending node.
4 . The QKD-based quantum digital signature method of claim 2 , further comprising:
disclosing a bitstring having a (3-1)-th length, which is part of the bitstring having the third length, and a bitstring having a (4-1)-th length, which is part of the bitstring having the fourth length,
wherein the (3-1)-th and (4-1)-th lengths are the same.
5 . The QKD-based quantum digital signature method of claim 4 , further comprising:
identifying a first error rate from the partial QKD process performed together with the message-sending node, using the disclosed bitstring having the (3-1)-th length, and identifying a second error rate from the partial QKD process performed together with the message-receiving node, using the disclosed bitstring having the (4-1)-th length.
6 . The QKD-based quantum digital signature method of claim 1 , wherein the generating the first trusted-node signature, further comprises generating the first trusted-node signature by randomly extracting a trusted-node bitstring having a (1-1)-th length from the trusted-node bitstring having the first length.
7 . The QKD-based quantum digital signature method of claim 6 , wherein the generating the second trusted-node signature, comprises performing quantum encoding for performing a partial QKD together with the message-receiving node, using a trusted-node bitstring having a (1-2)-th length, which is the entire trusted-node bitstring having the first length, except for the trusted-node bitstring having the (1-1)-th length.
8 . The QKD-based quantum digital signature method of claim 1 , wherein the verifying the first message, comprises: receiving an encrypted first message, which is obtained by encrypting the first message and a message-sending-node bitstring having a first length with the shared first secret key, from the message-sending node; extracting a decrypted first message and a decrypted message-sending-node bitstring having the first length by decrypting the received encrypted first message with the shared first secret key; determining whether the received encrypted first message has been sent by a legitimate sending node by comparing the decrypted message-sending-node bitstring having the first length with a trusted-node bitstring having a (1-1)-th length; sending a secondarily-encrypted first message, which is obtained by encrypting the decrypted first message and a trusted-node bitstring having a second length with the shared second secret key, to the message-receiving node, if a determination is made that the received encrypted first message has been sent by a legitimate sending node; and announcing to the message-receiving node that the message-sending node is a legitimate sending node and signatures for the first message are valid, based on a message-receiving-node bitstring having the second length, disclosed by the message-receiving node, and on the decrypted message-sending-node bitstring having the first length.
9 . The QKD-based quantum digital signature method of claim 8 , wherein the message-receiving-node bitstring having the second length is disclosed on a public board by the message-receiving node after determining, based on a decrypted trusted-node bitstring having the second length and the message-receiving-node bitstring having the second length, whether the secondarily-encrypted first message has been sent by a legitimate sending node.
10 . The QKD-based quantum digital signature method of claim 9 , wherein the determining whether the secondarily-encrypted first message has been sent by a legitimate sending node, comprises determining that the secondarily-encrypted first message has been sent by a legitimate sending node if a number of mismatching bits between the decrypted trusted-node bitstring having the second length and the message-receiving-node bitstring having the second length is less than a second error rate.
11 . The QKD-based quantum digital signature method of claim 8 , wherein the determining whether the received encrypted first message has been sent by a legitimate sending node, comprises determining that the received encrypted first message has been sent by a legitimate sending node if a number of mismatching bits between the decrypted message-sending-node bitstring having the first length and the trusted-node bitstring having the (1-1)-th length is less than a first error rate.
12 . The QKD-based quantum digital signature method of claim 8 , wherein the announcing to the message-receiving node, comprises announcing to the message-receiving node that the message-sending node is a legitimate sending node and the message-sending-node bitstring having the first length and the trusted-node bitstring having the second length are valid, if a number of mismatching bits between the disclosed message-receiving node bitstring having the second length and the decrypted message-sending-node bitstring having the first length is less than a sum of first and second error rates.
13 . A quantum key distribution (QKD)-based quantum digital signature method using a trusted node, the QKD-based quantum digital signature method being performed by the trusted node and comprising:
generating a first trusted-node signature by performing a partial QKD process together with a message-sending node; and
generating a second trusted-node signature by performing a partial QKD process together with a message-receiving node,
wherein
the first trusted-node signature is a trusted-node bitstring having a first length,
the second trusted-node signature is a trusted-node bitstring having a second length, and
a difference between the first length and the second length is determined based on a loss rate of a quantum channel between the trusted node and the message-sending node.
14 . The QKD-based quantum digital signature method of claim 13 , wherein the generating the first trusted-node signature, comprises: generating the first trusted-node signature by extracting a trusted-node bitstring having a (1-1)-th length from a trusted-node bitstring having a first length; and performing quantum encoding for performing a partial QKD together with the message-receiving node, using a trusted-node bitstring having a (1-2)-th length, which is the entire trusted-node bitstring having the first length, except for the trusted-node bitstring having the (1-1)-th length.
15 . A quantum key distribution (QKD)-based quantum digital signature method using a trusted node, the QKD-based quantum digital signature method being performed by the trusted node and comprising:
receiving an encrypted first message, which is obtained by encrypting a first message and a message-sending-node bitstring having a first length with a first secret key, from a message-sending node;
extracting a decrypted first message and a decrypted message sending-node bitstring having the first length by decrypting the received encrypted first message with the first secret key;
determining whether the received encrypted first message has been sent by a legitimate sending node by comparing the decrypted message-sending-node bitstring having the first length with a trusted-node bitstring having a (1-1)-th length;
sending a secondarily-encrypted first message, which is obtained by encrypting the decrypted first message and a trusted-node bitstring having a second length with a second secret key, to a message-receiving node, if a determination is made that the received encrypted first message has been sent by a legitimate sending node; and
announcing to the message-receiving node that the message-sending node is a legitimate sending node and signatures for the first message are valid, based on a message-receiving-node bitstring having the second length, disclosed by the message-receiving node, and on the decrypted message-sending-node bitstring having the first length,
wherein
a difference between the first length and the second length is determined based on a loss rate of a quantum channel between the trusted node and the message-sending node.
16 . The QKD-based quantum digital signature method of claim 15 , wherein the message-receiving-node bitstring having the second length is disclosed on a public board by the message-receiving node after determining, based on a decrypted trusted-node bitstring having the second length and the message-receiving-node bitstring having the second length, whether the secondarily-encrypted first message has been sent by a legitimate sending node.
17 . The QKD-based quantum digital signature method of claim 15 , wherein the determining whether the received encrypted first message has been sent by a legitimate sending node, comprises determining that the received encrypted first message has been sent by a legitimate sending node if a number of mismatching bits between a first message-sending-node signature and a first trusted-node signature is less than a first error rate.
18 . The QKD-based quantum digital signature method of claim 15 , wherein the announcing to the message-receiving node, comprises announcing to the message-receiving node that the first message has been sent by a legitimate sending node if a number of mismatching bits between a first message-receiving-node signature and a second trusted-node signature is less than a second error rate.
19 . The QKD-based quantum digital signature method of claim 15 , wherein
the first message is an email or contract,
the QKD-based quantum digital signature method further comprises completing authentication of an identify of a signer of the first message, if a determination is made that the message-sending node is a legitimate sending node and an announcement is made that the signatures for the first message are valid.