gpg

[t***@stg.hidro.cu]

hola estoy tratando de actualizar el repo de debian y me da este error

gpgv: Signature made mar 26 jun 2018 16:01:32 CDT
gpgv: using RSA key
A1BD8E9D78F7FE5C3E65D8AF8B48AD6246925553
gpgv: Can't check signature: No public key
gpgv: Signature made mar 26 jun 2018 16:01:32 CDT
gpgv: using RSA key
126C0D24BD8A2942CC7DF8AC7638D0442B90D010
gpgv: Can't check signature: No public key
.temp/.tmp/dists/stretch-backports/InRelease signature does not verify.
Errors:
.temp/.tmp/dists/stretch-backports/Release.gpg signature does not
verify
.temp/.tmp/dists/stretch-backports/InRelease signature does not verify


alguien pudiera ayudareme.