Database Reference
In-Depth Information
the decrypted data during the execution of the DELETE statement.
D(K,E(K,t
i
))
is the decryption of the encrypted data value in the
tuple
t
i
by a symmetric encryption key.
C
i
= L(user)
K = KCi
For 1≤i≤n
IF (t
i
[TC] = L(user))
{
t
i(temp)
= D(K,E(K,t
i
))
If (t
i(temp)
= p)
{
Display ti
}
i = i+1
}
Else
{
i = i+1
}
6.4.4 he UPDATE Statement
The UPDATE statement executed by a subject with security class
level L has the following general form [82]:
UPDATE R SET [A
1
=a
1
,A
2
=a
2
,...,A
n
=a
n
]
WHERE P
where R is the relation name, [
A
1
,A
2
,...,A
n
] are the attribute names,
and P is a predicate expression that may include conditions involving
classification attributes.
t
i(temp)
is a temporary tuple for the decrypted
data during the execution of the delete statement.
D(K,E(K,t
i
))
is
the decryption of the encrypted data value in the tuple
t
i
by a sym-
metric encryption key.
C
i
= L(user)
K = KCi
For 1≤i≤n
IF (t
i
[TC] = L(user))
{
t
i(temp)
= D(K, E(K, t
i
))
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