ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

ClouDedup:Secure Deduplication with

Encrypted DataPasquale Puzio

SecludIT & EURECOM

pasquale@secludit.com

Refik Molva (EURECOM)

Melek Önen (EURECOM)

Sergio Loureiro (SecludIT)

IEEE CloudCom 2013, Bristol, UK

December 3rd

ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Deduplication

● Storing duplicated data only once● Total space savings up to 90-95% in backup

applications

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Deduplication

...but it does not work on encrypted data!

D = Hello World

D = Hello World

ENCRYPTION with K1 ENCRYPTION with K2

owhfgr0wgr[whfrw0[h0[erghe0[gh0[eg

dfjl;dbfrwbfirbfroepthwobgfrugtwertgrtwu

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Convergent Encryption

Data Encryption key derived from Data

K = hash(Data)

D = Hello World

D = Hello World

ENCRYPTION with H(D) ENCRYPTION with H(D)

klfgwilegfiorwegtriegtiergieiergriegrigfifiw

klfgwilegfiorwegtriegtiergieiergriegrigfifiw

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Convergent Encryption

● Convergent Encryption is vulnerable to “dictionary attacks” [Perttula et al]

● Solutions based on key agreement infeasible in the Cloud

● How to achieve safe Convergent Encryption in the Cloud ?

⇨ Additional deterministic encryption with the same secret key for all users

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Solution – Additional Encryption

● Convergent encryption by Users● Additional Encryption by server/gateway

○ Deterministic ○ Unique key known only by the server○ No key exchange/sharing○ Security by design

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Solution - Metadata

Block-level deduplication + convergent encryption

⇨ New requirement: key management

SOLUTION▪ metadata manager

▪ deduplication on encrypted blocks ▪ management of block keys

▪ separation between data and metadata

⇨ independance from actual storage

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Metadata Manager

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Solution – putting all together

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Metadata Overhead

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Performance

● Storage/retrieval cost is linear with block count

● Deduplication cost is constant

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Security

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Conclusion

● Confidentiality and block-level deduplication● Countermeasure against CE vulnerabilities

● Negligible performance impact

● Storage agnostic● Transparent to the storage provider

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

Future Work

● Prototype for performance analysis (ongoing, current results are promising)

● Typical operations such as edit, append and delete

● Data sharing

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ClouDedup: Secure Deduplication with Encrypted Data for Cloud Storage Pasquale Puzio

THANK YOU