Handbook on Mobile and Ubiquitous Computing

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Handbook on Mobile and Ubiquitous Computing: Status and Perspective

14.3.1.2 Encryption

Ciphertext C =[(α

0

, β

0

); (α

1

, β

1

)] is generated from the following formulas using message m,

public key y, and random number r = (k

0

, k

1

). Ciphertext C is written in a RFID tag:

C =[(α

0

, β

0

); (α

1

, β

1

)],

α

0

= my

k

0

, β

0

= g

k

0

, α

1

= y

k

1

, β

1

= g

k

1

14.3.1.3 Decryption

The reader for reading ID information receives ciphertext C from a RFID tag, and sends it

to a database. A database calculates the decryption algorithm described as follows. Compute

m

0

= α

0

/β

x

0

and m

1

=α

1

/β

x

1

using ciphertext C =[(α

0

, β

0

); (α

1

, β

1

)] under public key y from

a RFID tag and secret key x.Ifm

1

=1, then output message m =m

0

. Otherwise the decryption

fails, and a special symbol ⊥ is output. A given