US Patent 7908490 Techniques for synchronizing and archive-versioning of encrypted files

Techniques are presented for synchronizing and archive-versioning encrypted files. Blocks of encrypted data are managed and metadata is maintained for the blocks. The metadata identifies a maximum number of blocks and an index or parameter string. The string includes transaction identifiers and relative block numbers. The metadata is used as parameter information to a hash algorithm along with a hash key to acquire a unique initialization vector for each block. Each initialization vector when supplied to a cipher service along with a particular block of data produces an encrypted version of the data supplied or supplies a decrypted version of the data supplied. The techniques are also applied to files being archived and versioned from a storage volume.