weak key used for an Initial Vector

[Denis Corbin]

On 07/08/2015 09:08, Werner Koch wrote:
> On Thu,  6 Aug 2015 22:33, dar.linux at free.fr said:

Hello,

> 
>> I've found googling that it was possible to disable the weak key 
>> warning thanks to the PRIV_CTL_DISABLE_WEAK_KEY value given to 
>> gcry_cipher_ctl()
> 
> No, that is not possible.  This symbol is private to libgcrypt; it 
> is not defined as part of the public API and thus also not in 
> gcrypt.h.

OK. How then to decipher very old data encrypted more than 10 years
ago at which time the error about weak key was not issued?

Regards,
Denis.