Undefined reference errors when linking libzip with GnuTLS/Nettle on Linux

[Vicky8472]

Hello,
I’m integrating libzip into my project on Linux and I’m encountering several undefined reference linker errors related to GnuTLS and Nettle, even though libzip builds successfully.

Here is a sample of the errors:

/usr/bin/ld: libzip.a(zip_crypto_gnutls.c.o): in function _zip_crypto_aes_new': undefined reference to nettle_aes128_set_encrypt_key'
undefined reference to nettle_aes192_set_encrypt_key' undefined reference to nettle_aes256_set_encrypt_key'

/usr/bin/ld: libzip.a(zip_crypto_gnutls.c.o): in function _zip_crypto_hmac_new': undefined reference to gnutls_hmac_init'
...
undefined reference to `nettle_pbkdf2_hmac_sha1'

I built libzip using CMake inside my project:

libzip build folder: thirdparty/libzip/build

Linking against static libzip.a

It looks like libzip’s crypto backend is automatically using GnuTLS + Nettle, but during final linking these dependencies are not automatically added.

Questions:

What is the recommended way to correctly link the required GnuTLS/Nettle libraries when using a static libzip.a?

Is there a CMake option to disable GnuTLS and crypto support entirely (I only need basic ZIP read/write)?

Or, should I explicitly link these libraries?

gnutls

nettle

hogweed

System:

Linux (Ubuntu-based)

GCC

Building a static binary

Any guidance on the correct link flags or configuration would be very helpful.
Thank you!

[dillof]

hi,

when using static libraries, the dependencies of those libraries are not automatically pulled in by the linker (that's not specific to libzip). So you will have to link them explicitly.

As described in INSTALL.md, if you want to disable encryption support, you can disable the relevant libraries when configuring: cmake -DENABLE_GNUTLS=OFF -DENABLE_MBEDTLS=OFF -DENABLE_OPENSSL=OFF.

yours,
dillo