Cannot build my docker file on Fedora, apk add says : "BAD signature"

Hi,

Here's my dockerFile :

# cat dockerImages/sebM_MiniLinux
FROM docker.io/alpine:latest
RUN apk update -q
RUN apk add bash
ENTRYPOINT ["bash"]

Can't build my docker file on Fedora, apk add says : "BAD signature" :

# docker build -t sebm/alpine -f dockerImages/sebM_MiniLinux dockerImages/
Sending build context to Docker daemon  2.048kB
Step 1/4 : FROM docker.io/alpine:latest
 ---> 389fef711851
Step 2/4 : RUN apk update -q
 ---> Using cache
 ---> e831e51bb70a
Step 3/4 : RUN apk add bash
 ---> Running in b58aa08893aa
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ncurses-terminfo-base (6.2_p20200523-r0)
ERROR: ncurses-terminfo-base-6.2_p20200523-r0: BAD signature
(2/4) Installing ncurses-libs (6.2_p20200523-r0)
(3/4) Installing readline (8.0.4-r0)
ERROR: ncurses-libs-6.2_p20200523-r0: BAD signature
(4/4) Installing bash (5.0.17-r0)
ERROR: bash-5.0.17-r0: BAD signature
3 errors; 6 MiB in 15 packages
The command '/bin/sh -c apk add bash' returned a non-zero code: 3
# echo $?
3

I'm using docker v20.10.1.

Can you please help me ?