/usr/include/sodium/ is in libsodium-dev 1.0.11-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/sodium/core.h
/usr/include/sodium/crypto_aead_aes256gcm.h
/usr/include/sodium/crypto_aead_chacha20poly1305.h
/usr/include/sodium/crypto_auth.h
/usr/include/sodium/crypto_auth_hmacsha256.h
/usr/include/sodium/crypto_auth_hmacsha512.h
/usr/include/sodium/crypto_auth_hmacsha512256.h
/usr/include/sodium/crypto_box.h
/usr/include/sodium/crypto_box_curve25519xsalsa20poly1305.h
/usr/include/sodium/crypto_core_hchacha20.h
/usr/include/sodium/crypto_core_hsalsa20.h
/usr/include/sodium/crypto_core_salsa20.h
/usr/include/sodium/crypto_core_salsa2012.h
/usr/include/sodium/crypto_core_salsa208.h
/usr/include/sodium/crypto_generichash.h
/usr/include/sodium/crypto_generichash_blake2b.h
/usr/include/sodium/crypto_hash.h
/usr/include/sodium/crypto_hash_sha256.h
/usr/include/sodium/crypto_hash_sha512.h
/usr/include/sodium/crypto_int32.h
/usr/include/sodium/crypto_int64.h
/usr/include/sodium/crypto_onetimeauth.h
/usr/include/sodium/crypto_onetimeauth_poly1305.h
/usr/include/sodium/crypto_pwhash.h
/usr/include/sodium/crypto_pwhash_argon2i.h
/usr/include/sodium/crypto_pwhash_scryptsalsa208sha256.h
/usr/include/sodium/crypto_scalarmult.h
/usr/include/sodium/crypto_scalarmult_curve25519.h
/usr/include/sodium/crypto_secretbox.h
/usr/include/sodium/crypto_secretbox_xsalsa20poly1305.h
/usr/include/sodium/crypto_shorthash.h
/usr/include/sodium/crypto_shorthash_siphash24.h
/usr/include/sodium/crypto_sign.h
/usr/include/sodium/crypto_sign_ed25519.h
/usr/include/sodium/crypto_sign_edwards25519sha512batch.h
/usr/include/sodium/crypto_stream.h
/usr/include/sodium/crypto_stream_aes128ctr.h
/usr/include/sodium/crypto_stream_chacha20.h
/usr/include/sodium/crypto_stream_salsa20.h
/usr/include/sodium/crypto_stream_salsa2012.h
/usr/include/sodium/crypto_stream_salsa208.h
/usr/include/sodium/crypto_stream_xsalsa20.h
/usr/include/sodium/crypto_uint16.h
/usr/include/sodium/crypto_uint32.h
/usr/include/sodium/crypto_uint64.h
/usr/include/sodium/crypto_uint8.h
/usr/include/sodium/crypto_verify_16.h
/usr/include/sodium/crypto_verify_32.h
/usr/include/sodium/crypto_verify_64.h
/usr/include/sodium/export.h
/usr/include/sodium/randombytes.h
/usr/include/sodium/randombytes_salsa20_random.h
/usr/include/sodium/randombytes_sysrandom.h
/usr/include/sodium/runtime.h
/usr/include/sodium/utils.h
/usr/include/sodium/version.h