In order to support SSL HTTPS connections in Civetweb on Windows, your will have to use the GPLv2 licensed CyaSSL library. By using this library, the resulting binary will have to have the same license unless you buy a commercial license from wolfSSL.
If you download to cyaSSL to cyassl-2.7.0 in a directory parallel to with Civetweb, you can open the VS2012/civetweb_yassl solution in Visual Studio.
cyassl_directory\ cyassl_directory\cyassl
USE_YASSL NO_SSL_DL
OPENSSL_EXTRA HAVE_ERRNO_H HAVE_GETHOSTBYNAME HAVE_INET_NTOA HAVE_LIMITS_H HAVE_MEMSET HAVE_SOCKET HAVE_STDDEF_H HAVE_STDLIB_H HAVE_STRING_H HAVE_SYS_STAT_H HAVE_SYS_TYPES_H
ctaocrypt/src/aes.c ctaocrypt/src/arc4.c ctaocrypt/src/asn.c ctaocrypt/src/coding.c ctaocrypt/src/des3.c ctaocrypt/src/dh.c ctaocrypt/src/dsa.c ctaocrypt/src/ecc.c ctaocrypt/src/error.c ctaocrypt/src/hc128.c ctaocrypt/src/hmac.c ctaocrypt/src/integer.c ctaocrypt/src/logging.c ctaocrypt/src/md2.c ctaocrypt/src/md4.c ctaocrypt/src/md5.c ctaocrypt/src/memory.c ctaocrypt/src/misc.c ctaocrypt/src/pwdbased.c ctaocrypt/src/rabbit.c ctaocrypt/src/random.c ctaocrypt/src/ripemd.c ctaocrypt/src/rsa.c ctaocrypt/src/sha.c ctaocrypt/src/sha256.c ctaocrypt/src/sha512.c ctaocrypt/src/tfm.c src/crl.c src/internal.c src/io.c src/keys.c src/ocsp.c src/sniffer.c src/ssl.c src/tls.c