On Thu, Mar 21, 2019 at 7:46 AM Antonin Houska <ah@cybertec.at> wrote:
> Nevertheless, with the current version of our patch, PG should be resistant
> against such a partial write anyway because we chose to align XLOG records to
> 16 bytes (as long as the encryption is enabled) for the following reasons:
>
> If one XLOG record ends and the following one starts in the same encryption
> block, both records can get corrupted during streaming replication. The
> scenario looks like: 1) the first record is written on master (the unused part
> of the block contains zeroes), 2) the block is encrypted and its initial part
> (i.e. the number of bytes occupied by the first record in the plain text) is
> streamed to slave, 3) the second record is written on master, 4) the
> containing encryption block is encrypted again and the trailing part (i.e. the
> number of bytes occupied by the second record) is streamed, 5) decryption of
> the block on slave will produce garbage and thus corrupt both records. This is
> because the trailing part of the block was filled with zeroes during
> encryption, but it contains different data at decryption time.
Wouldn't Tom's proposal to use a stream cipher fix all this?
--
Robert Haas
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