Unable to decrypt file copied from USB thumb drive.

[Dirk-Willem van Gulik]

On 29 Oct 2021, at 10:17, Chris Taylor <chris at christaylordeveloper.co.uk> wrote:
> I am developing a backup process for personal files, on USB thumb drive.  I tar and zip my files (30GB) then encrypt them with:
> 
> gpg --no-symkey-cache --symmetric --cipher-algo AES256 my-backup.tar.gz
> 
> I copy my-backup.tar.gz.gpg to my USB thumb drive.  I am using Ubuntu so the USB drive is formatted to Ext4.
> 
> I try to decrypt with:
> 
> gpg --output my-backup.tar.gz --decrypt my-backup.tar.gz.gpg
> 
> and get the following error:
> 
> gpg: AES256 encrypted data
> gpg: encrypted with 1 passphrase
> gpg: block_filter 0x0000556d112aa1e0: read error (size=13328,a->size=13328)
> gpg: WARNING: encrypted message has been manipulated!
> gpg: block_filter: pending bytes!
> 
> I have gpg version 2.2.19, libgcrypt 1.8.5.  Without encryption this process has worked perfectly well many times.

I'd first check with something like

	openssl sha256  my-backup.tar.gz

prior to copy / post copy if your thumb drive is good.

Dw.