1. Attribute Based Encryption
B.Saikrishna
S.N.Bose Scholars Program Summer Research Internship.
Guided by Prof. Manoj Prabhakaran and Shashank Agrawal.
July 26,2013
B.Saikrishna (IIT-Madras) July 26,2013 1 / 12

2. What is cryptography?
1 Secure communication.
2 Protection from third parties or “adversaries”.
B.Saikrishna (IIT-Madras) July 26,2013 2 / 12

3. Applications
1 Online Banking
2 Cloud storage
3 Security of the entire digital world!
B.Saikrishna (IIT-Madras) July 26,2013 3 / 12

4. Encryption and Decryption
1 Encryption is the conversion of plaintext data into a form from which
the underlying plaintext cannot be recovered by anyone not
authorised to recover it.
2 Decryption is the process by which the underlying plaintext message
is recovered from an encrypted ciphertext.
B.Saikrishna (IIT-Madras) July 26,2013 4 / 12

5. Private Key Cryptography
B.Saikrishna (IIT-Madras) July 26,2013 5 / 12

6. Public Key Cryptography
B.Saikrishna (IIT-Madras) July 26,2013 6 / 12

7. Attribute Based Encryption
1 A paradigm in which the decryption of a ciphertext is possible only if
the attributes in the key match the attributes in the ciphertext.
2 An attribute could be anything. Example :
location,name,designation,etc.
3 A popular use of this is in the case of organisations.
B.Saikrishna (IIT-Madras) July 26,2013 7 / 12

8. Other Applications Of ABE
1 Cloud storage and retrieval.
2 To outsource complex computations to a cloud device,while also
maintaining secrecy of data.
B.Saikrishna (IIT-Madras) July 26,2013 8 / 12

9. Predicate Encryption
1 A modification of ABE where keys are associated with
“predicates”(functions).
2 A ciphertext can be decrypted by a key if the attribute within the
ciphertext satisfies the function present in the key.
3 We worked with functions called “inner products” which are similar to
the vector dot products.
4 Ultimate goal is to realise all “polynomial time ” functions.
B.Saikrishna (IIT-Madras) July 26,2013 9 / 12

10. Our Work
1 Predicate Based encryption schemes in the public and private key
settings.
2 We prove our schemes to be secure under different notions of
security- attribute hiding , predicate hiding.
3 More efficient than the currently existing schemes( in terms of size
and amount of computation needed)
4 On the downside,we use “stronger” assumptions.
B.Saikrishna (IIT-Madras) July 26,2013 10 / 12

11. Future Work
1 To base our schemes on “weaker” and lesser assumptions.
2 To improve the efficiency even more.
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12. Thank you!
B.Saikrishna (IIT-Madras) July 26,2013 12 / 12