Olá galera, vou mostrar como usar ASP para autenticar sua aplicação no Facebook.

Precisamos de dois arquivos fundamentais:

Arquivo de Função de acesso ao Facebook (achei na net, não lembro o autor, mais não tirei o cabeçalho): LINK

Arquivo de configuração jSON para ASP (retirado do site oficial do jSON: LINK.

Você vai precisar de uma função de base64, eu adicionei a de Encode e Decode, caso precisem em outros projetos.

Você precisa adicionar o ID da sua aplicação, A URL de retorno (não precisa mudar a query que coloquei, facilita a autenticação em um arquivo só), e as permissões em sequencia (isso você acha no facebook developer).

Eu salvei tudo em Session, o token, o signed request e o ID do usuário do facebook:

set user = JSON.parse(base64Decode(playload))
session("signed_request") = request("signed_request")
session("oauth_token") = user.oauth_token
session("id_atual") = user.user_id
response.redirect("pagina.asp")

E Adicionei um Redirect para quando estiver autenticado:

Segue o Código completo:

<script language="javascript" runat="server" src="json2.asp"></script>
<!-- #include file="fb_app.asp" -->
<%
session.lcid = 1046
session.timeOut = 1440
server.scriptTimeOut = 999999999

if (request.QueryString("logar") = "") then
	main
	function main
		dim strJSON
		dim URL
		dim sToken
		dim user
		dim loc

		set cookie = get_facebook_cookie( FACEBOOK_APP_ID, FACEBOOK_SECRET )
		if cookie.count > 0 then
			response.write "Logado... Ok! <br/>"
			sToken = cookie("access_token")
			url = "https://graph.facebook.com/me?access_token=" & sToken
			strJSON = get_page_contents(URL) 

			set user = JSON.parse(strJSON)
			response.write cookie("access_token")
		else
			link = "http://www.facebook.com/dialog/oauth?client_id=ID_DA_SUA_APLICAÇÃO&redirect_uri="&server.URLEncode("http://apps.facebook.com/NOME_DA_MINHA_APP/autenticacao.asp?logar=ok")&"&scope=offline_access,user_location,email,publish_stream,user_birthday,read_friendlists"
			response.write("<script>top.location.href='" & link & "';</script>")
		end if
	end function
else
	const BASE_64_MAP_INIT ="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
	dim nl
	dim Base64EncMap(63)
	dim Base64DecMap(127)

	public sub initCodecs()
		nl = "<P>" & chr(13) & chr(10)
		dim max, idx
		   max = len(BASE_64_MAP_INIT)
		for idx = 0 to max - 1
			 Base64EncMap(idx) = mid(BASE_64_MAP_INIT, idx + 1, 1)
		next
		for idx = 0 to max - 1
			 Base64DecMap(asc(Base64EncMap(idx))) = idx
		next
	end sub

	public function base64Encode(plain)
		if len(plain) = 0 then
			 base64Encode = ""
			 exit function
		end if
		dim ret, ndx, by3, first, second, third
		by3 = (len(plain) \ 3) * 3
		ndx = 1
		do while ndx <= by3
			 first  = asc(mid(plain, ndx + 0, 1))
			 second = asc(mid(plain, ndx + 1, 1))
			 third  = asc(mid(plain, ndx + 2, 1))
			 ret = ret & Base64EncMap((first \ 4) and 63)
			 ret = ret & Base64EncMap(((first * 16) and 48) + ((second \ 16) and 15))
			 ret = ret & Base64EncMap(((second * 4) and 60) + ((third \ 64) and 3))
			 ret = ret & Base64EncMap(third and 63)
			 ndx = ndx + 3
		loop
		if by3 < len(plain) then
			 first  = asc(mid(plain, ndx + 0, 1))
			 ret = ret & Base64EncMap((first \ 4) and 63)
			 if (len(plain) MOD 3) = 2 then
				  second = asc(mid(plain, ndx+1, 1))
				  ret = ret & Base64EncMap(((first * 16) and 48) + ((second \ 16) and 15))
				  ret = ret & Base64EncMap(((second * 4) and 60))
			 else
				  ret = ret & Base64EncMap((first * 16) and 48)
				  ret = ret & "="
			 end if
			 ret = ret & "="
		end if
		base64Encode = ret
	end function

	public function base64Decode(scrambled)
		if len(scrambled) = 0 then
			 base64Decode = ""
			 exit function
		end if
		dim realLen
		realLen = len(scrambled)
		do while mid(scrambled, realLen, 1) = "="
			 realLen = realLen - 1
		loop
		dim ret, ndx, by4, first, second, third, fourth
		ret = ""
		by4 = (realLen \ 4) * 4
		ndx = 1
		do while ndx <= by4
			 first  = Base64DecMap(asc(mid(scrambled, ndx+0, 1)))
			 second = Base64DecMap(asc(mid(scrambled, ndx+1, 1)))
			 third  = Base64DecMap(asc(mid(scrambled, ndx+2, 1)))
			 fourth = Base64DecMap(asc(mid(scrambled, ndx+3, 1)))
			 ret = ret & chr(((first * 4) and 255) + ((second \ 16) and 3))
			 ret = ret & chr(((second * 16) and 255) + ((third \ 4) and 15))
			 ret = ret & chr(((third * 64) and 255) + (fourth and 63))
			 ndx = ndx + 4
		loop
		if ndx < realLen then
			 first  = Base64DecMap(asc(mid(scrambled, ndx+0, 1)))
			 second = Base64DecMap(asc(mid(scrambled, ndx+1, 1)))
			 ret = ret & chr(((first * 4) and 255) + ((second \ 16) and 3))
			 if realLen mod 4 = 3 then
				  third = Base64DecMap(asc(mid(scrambled,ndx+2,1)))
				  ret = ret & chr(((second * 16) and 255) + ((third \ 4) and 15))
			 end if
		end if
		base64Decode = ret
	end function
	call initCodecs

	splitvar = split(request("signed_request"), ".")
	encoded_sig = splitvar(0)
	playload = splitvar(1)

	set user = JSON.parse(base64Decode(playload))
	session("signed_request") = request("signed_request")
	session("oauth_token") = user.oauth_token
	session("id_atual") = user.user_id
	response.redirect("animacao.asp")
end if
%>