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Other interesting issues:. Compression within record - e.g. code selection collection of records - e.g. find common patterns Encryption. Encrypting Records. new record r. E(r). trusted processor. dbms. E(r 1 ) E(r 2 ) E(r 3 ) E(r 4 ). Encrypting Records. search F(r)=x. ??.

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Other interesting issues
Other interesting issues:

  • Compression

    • within record - e.g. code selection

    • collection of records - e.g. find common patterns

  • Encryption


Encrypting records
Encrypting Records

new

record

r

E(r)

trusted

processor

dbms

E(r1)

E(r2)

E(r3)

E(r4)

...


Encrypting records1
Encrypting Records

search

F(r)=x

??

trusted

processor

dbms

E(r1)

E(r2)

E(r3)

E(r4)

...


Search key in the clear
Search Key in the Clear

search

k=2

Q: k=2

A: [2, E(b2)]

trusted

processor

dbms

[1, E(b1)]

[2, E(b2)]

[3, E(b3)]

[4, E(b4)]

...

  • each record is [k,b]

  • store [k, E(b)]

  • can search for records with k=x


Encrypt key
Encrypt Key

search

k=2

Q: k’=E(2)

A: [E(2), E(b2)]

trusted

processor

dbms

[E(1), E(b1)]

[E(2), E(b2)]

[E(3), E(b3)]

[E(4), E(b4)]

...

  • each record is [k,b]

  • store [E(k), E(b)]

  • can search for records with k=E(x)


Issues
Issues

  • Hard to do range queries

  • Encryption not so good.

  • Better to use encryption that does not always generate same cyphertext

k

k

E(k, random)

E

D

simplification


How do we search now
How Do We Search Now?

???

search

k=2

A: [E(2,dhe), E(b2)]

[E(2, lkz), E(b4)]

Q: k’=E(2)

trusted

processor

dbms

[E(1, abc), E(b1)]

[E(2, dhe), E(b2)]

[E(3, nft), E(b3)]

[E(2, lkz), E(b4)]

...

  • each record is [k,b]

  • store [E(k, rand), E(b)]

  • can search for records with k=E(x,???)?


Solution
Solution?

  • Develop new decryption function: D(f(k1), E(k2, rand)) is true if k1=k2


Solution1
Solution

  • Develop new decryption function: D(f(k1), E(k2, rand)) is true if k1=k2

Q: check if D(f(2),*) true

search

k=2

A: [E(2,dhe), E(b2)]

[E(2, lkz), E(b4)]

trusted

processor

dbms

[E(1, abc), E(b1)]

[E(2, dhe), E(b2)]

[E(3, nft), E(b3)]

[E(2, lkz), E(b4)]

...


Issues1
Issues

  • Cannot do non-equality predicates

  • Hard to build indexes


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