A script to automate installing SmashEnabler.kext, while also being a bit easier to debug what exactly happens on some systems.

install_smashenabler.sh

#!/bin/sh
# shellcheck shell=dash

# This is just a little script that can be downloaded from the internet to
# install SmashEnabler. 
#
# It runs on Unix shells like {a,ba,da,k,z}sh. It uses the common `local`
# extension. Note: Most shells limit `local` to 1 var per line, contra bash.
#
# Borrow heavily and liberally from rustup's install script. ;P

set -u

usage() {
    cat 1>&2 <<EOF
smashenabler-installer 0.0.1 (2020-07-20)
The installer for SmashEnabler.kext

USAGE:
     [FLAGS] [OPTIONS]
EOF
}

main() {
    downloader --check

    local _url="https://forums.dolphin-emu.org/attachment.php?aid=16637"
    say "Downloading kext from ${_url}."

    local _file="SmashEnabler.kext"
    ensure downloader "$_url" "$_file"

    say "Installing kext. This may require your password."
    sudo mv "$_file" /Library/Extensions/SmashEnabler.kext
    sudo chown -R root:wheel /Library/Extensions/SmashEnabler.kext
    sudo touch /Library/Extensions

    say "Kext installed. You should boot into recovery mode and re-enable SIP to be safe."

    local _retval=$?
    return "$_retval"
}

say() {
    printf 'smashenabler-installer: %s\n' "$1"
}

err() {
    say "$1" >&2
    exit 1
}

need_cmd() {
    if ! check_cmd "$1"; then
        err "need '$1' (command not found)"
    fi
}

check_cmd() {
    command -v "$1" > /dev/null 2>&1
}

assert_nz() {
    if [ -z "$1" ]; then err "assert_nz $2"; fi
}

# Run a command that should never fail. If the command fails execution
# will immediately terminate with an error showing the failing
# command.
ensure() {
    if ! "$@"; then err "command failed: $*"; fi
}

# This is just for indicating that commands' results are being
# intentionally ignored. Usually, because it's being executed
# as part of error handling.
ignore() {
    "$@"
}

# This wraps curl or wget. Try curl first, if not installed,
# use wget instead.
downloader() {
    local _dld
    local _ciphersuites
    if check_cmd curl; then
        _dld=curl
    elif check_cmd wget; then
        _dld=wget
    else
        _dld='curl or wget' # to be used in error message of need_cmd
    fi

    if [ "$1" = --check ]; then
        need_cmd "$_dld"
    elif [ "$_dld" = curl ]; then
        get_ciphersuites_for_curl
        _ciphersuites="$RETVAL"
        if [ -n "$_ciphersuites" ]; then
            curl --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2"
        else
            echo "Warning: Not enforcing strong cipher suites for TLS, this is potentially less secure"
            if ! check_help_for "$3" curl --proto --tlsv1.2; then
                echo "Warning: Not enforcing TLS v1.2, this is potentially less secure"
                curl --silent --show-error --fail --location "$1" --output "$2"
            else
                curl --proto '=https' --tlsv1.2 --silent --show-error --fail --location "$1" --output "$2"
            fi
        fi
    elif [ "$_dld" = wget ]; then
        get_ciphersuites_for_wget
        _ciphersuites="$RETVAL"
        if [ -n "$_ciphersuites" ]; then
            wget --https-only --secure-protocol=TLSv1_2 --ciphers "$_ciphersuites" "$1" -O "$2"
        else
            echo "Warning: Not enforcing strong cipher suites for TLS, this is potentially less secure"
            if ! check_help_for "$3" wget --https-only --secure-protocol; then
                echo "Warning: Not enforcing TLS v1.2, this is potentially less secure"
                wget "$1" -O "$2"
            else
                wget --https-only --secure-protocol=TLSv1_2 "$1" -O "$2"
            fi
        fi
    else
        err "Unknown downloader"   # should not reach here
    fi
}

check_help_for() {
    local _arch
    local _cmd
    local _arg
    _arch="$1"
    shift
    _cmd="$1"
    shift

    case "$_arch" in
        # If we're running on OS-X, older than 10.13, then we always
        # fail to find these options to force fallback
        *darwin*)
        if check_cmd sw_vers; then
            if [ "$(sw_vers -productVersion | cut -d. -f2)" -lt 13 ]; then
                # Older than 10.13
                echo "Warning: Detected OS X platform older than 10.13"
                return 1
            fi
        fi
        ;;

    esac

    for _arg in "$@"; do
        if ! "$_cmd" --help | grep -q -- "$_arg"; then
            return 1
        fi
    done

    true # not strictly needed
}

# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
# if support by local tools is detected. Detection currently supports these curl backends: 
# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
get_ciphersuites_for_curl() {
    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
        # user specified custom cipher suites, assume they know what they're doing
        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
        return
    fi

    local _openssl_syntax="no"
    local _gnutls_syntax="no"
    local _backend_supported="yes"
    if curl -V | grep -q ' OpenSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' LibreSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' BoringSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' GnuTLS/'; then
        _gnutls_syntax="yes"
    else
        _backend_supported="no"
    fi

    local _args_supported="no"
    if [ "$_backend_supported" = "yes" ]; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "curl" "--tlsv1.2" "--ciphers" "--proto"; then
            _args_supported="yes"
        fi
    fi

    local _cs=""
    if [ "$_args_supported" = "yes" ]; then
        if [ "$_openssl_syntax" = "yes" ]; then
            _cs=$(get_strong_ciphersuites_for "openssl")
        elif [ "$_gnutls_syntax" = "yes" ]; then
            _cs=$(get_strong_ciphersuites_for "gnutls")
        fi
    fi

    RETVAL="$_cs"
}

# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
# if support by local tools is detected. Detection currently supports these wget backends: 
# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
get_ciphersuites_for_wget() {
    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
        # user specified custom cipher suites, assume they know what they're doing
        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
        return
    fi

    local _cs=""
    if wget -V | grep -q '\-DHAVE_LIBSSL'; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
            _cs=$(get_strong_ciphersuites_for "openssl")
        fi
    elif wget -V | grep -q '\-DHAVE_LIBGNUTLS'; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
            _cs=$(get_strong_ciphersuites_for "gnutls")
        fi
    fi

    RETVAL="$_cs"
}

# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2 
# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad 
# DH params often found on servers (see RFC 7919). Sequence matches or is
# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.  
# $1 must be openssl or gnutls.
get_strong_ciphersuites_for() {
    if [ "$1" = "openssl" ]; then
        # OpenSSL is forgiving of unknown values, no problems with TLS 1.3 values on versions that don't support it yet.
        echo "TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384"
    elif [ "$1" = "gnutls" ]; then
        # GnuTLS isn't forgiving of unknown values, so this may require a GnuTLS version that supports TLS 1.3 even if wget doesn't.
        # Begin with SECURE128 (and higher) then remove/add to build cipher suites. Produces same 9 cipher suites as OpenSSL but in slightly different order.
        echo "SECURE128:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS-ALL:-CIPHER-ALL:-MAC-ALL:-KX-ALL:+AEAD:+ECDHE-ECDSA:+ECDHE-RSA:+AES-128-GCM:+CHACHA20-POLY1305:+AES-256-GCM"
    fi 
}

main "$@" || exit 1