[PATCH 0/5] net: lwip: root certificates

Da Xue da at lessconfused.com
Tue Jul 15 06:45:43 CEST 2025


Hi Jerome,

> Then new Kconfig symbols are added to support providing the certificates
> at build time, as a DER or PEM encoded X509 collection:
> WGET_BUILTIN_CACERT=y and WGET_BUILTIN_CACERT_PATH=<some path>.
> Note that PEM support requires MBEDTLS_LIB_X509_PEM=y (for the cacert
> command as well as for the builtin way).
>
> Here is a complete example (showing only the relevant output from the
> various commands):
>
>  make qemu_arm64_lwip_defconfig
>  wget https://curl.se/ca/cacert.pem
>  echo CONFIG_WGET_BUILTIN_CACERT=y >>.config
>  echo CONFIG_WGET_BUILTIN_CACERT_PATH=cacert.pem >>.config
>  make olddefconfig
>  make -j$(nproc) CROSS_COMPILE="ccache aarch64-linux-gnu-"
>  qemu-system-aarch64 -M virt -nographic -cpu max \
>         -object rng-random,id=rng0,filename=/dev/urandom \
>         -device virtio-rng-pci,rng=rng0 -bios u-boot.bin
>  => dhcp
>  # HTTPS transfer using the builtin CA certificates
>  => wget https://www.google.com/
>  18724 bytes transferred in 15 ms (1.2 MiB/s)
>  # Disable certificate validation
>  => wget cacert 0 0
>  # Unsafe HTTPS transfer
>  => wget https://www.google.com/
>  WARNING: no CA certificates, HTTPS connections not authenticated
>  16570 bytes transferred in 15 ms (1.1 MiB/s)
>  # Dowload and apply CA certificates from the net
>  => wget https://curl.se/ca/cacert.pem
>  WARNING: no CA certificates, HTTPS connections not authenticated
>  ##
>  233263 bytes transferred in 61 ms (3.6 MiB/s)
>  => wget cacert $fileaddr $filesize
>  # Now HTTPS is authenticated against the new CA
>  => wget https://www.google.com/
>  18743 bytes transferred in 14 ms (1.3 MiB/s)
>  # Drop the certificates again...
>  => wget cacert 0 0
>  # Check that transfer is not secure
>  => wget https://www.google.com/
>  WARNING: no CA certificates, HTTPS connections not authenticated
>  # Restore the builtin CA
>  => wget cacert builtin
>  # No more WARNING
>  => wget https://www.google.com/
>  18738 bytes transferred in 15 ms (1.2 MiB/s)

Is there a simple way to convert multi-certificate root trust pem to
der? I tried packing it as a PKCS#7 and got "Could not parse
certificates (-8576)"

Best Regards,
Da


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