HEADER=$(printf '{"alg":"HS256","typ":"JWT"}' | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')
PAYLOAD=$(cat payload.json | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')
SIGNATURE=$(printf "%s.%s" "$HEADER" "$PAYLOAD" | openssl dgst -binary -sha256 -hmac "my-secret-key" | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')

echo "$HEADER.$PAYLOAD.$SIGNATURE"

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