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7.0 Cryptographic Technologies for Big Data (cont.)
masking, the proposed scheme is able to preserve data privacy when a TPA audits the
data set stored in the servers at different tiers.
7.10 Consider convergent encryption for deduplication
7.10.1 Why?
To improve efficiency of storage usage. Data stored on a cloud is typically encrypted.
However, using common encryption scheme, even the same file results in different
ciphertext. Since the cloud service provider cannot tell whether they are actually the
identical data or not, there may be a situation where duplicated copies of the same data
may unnecessarily remain on the cloud.
7.10.2 How?
If deduplication is desired, convergent encryption scheme—which was originally
proposed in [SGLM08]—can be considered. It uses an encryption key that is
deterministically derived from the plaintext data to be encrypted (i.e. cryptographic hash
value of the data, and thereby the resulting ciphertext becomes identical). This way,
deduplication of the identical data is made possible.
CLOUD SECURITY ALLIANCE Big Data Working Group Guidance
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