Unable to decrypt file copied from USB thumb drive.

[Chris Taylor]

Thank you - I will check.

Almost certainly the hash of my .gpg file will be different after it has 
passed through the Thumb Drive.  However, no other files on the Thumb 
Drive get corrupted.  So, my question will probably become how can I 
protect my .gpg file when it is moved off my laptop onto other meda?

Chris.


On 29/10/2021 12:05, Dirk-Willem van Gulik wrote:
> 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.