Re: [Proposal] Table-level Transparent Data Encryption (TDE) and KeyManagement Service (KMS)

On Tue, Aug  6, 2019 at 01:55:38PM -0400, Bruce Momjian wrote:
> CTR mode creates a bit stream for the first 16 bytes with nonce of
> (segment_number, counter = 0), and the next 16 bytes with 
> (segment_number, counter = 1), etc.  We only XOR using the parts of the
> bit stream we want to use.  We don't care what the WAL content is --- we
> just XOR it with the stream with the matching counter for that part of
> the WAL.

The diagram which is part of this section might be helpful:

    https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_(CTR)
    https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#/media/File:CTR_encryption_2.svg

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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