Convergent_encryption
Convergent encryption
Encryption method
Convergent encryption, also known as content hash keying, is a cryptosystem that produces identical ciphertext from identical plaintext files. This has applications in cloud computing to remove duplicate files from storage without the provider having access to the encryption keys.[1] The combination of deduplication and convergent encryption was described in a backup system patent filed by Stac Electronics in 1995.[2] This combination has been used by Farsite,[3] Permabit,[4] Freenet, MojoNation, GNUnet, flud, and the Tahoe Least-Authority File Store.[5]
The system gained additional visibility in 2011 when cloud storage provider Bitcasa announced they were using convergent encryption to enable de-duplication of data in their cloud storage service.[6]