Библиотека Twitter OAuth без Indy. Переходим на ICS.

TIdURI = class
  protected
    FDocument: string;
    [....]
  public
    [...]    
    class function URLDecode(ASrc: string): string;
    class function URLEncode(const ASrc: string): string;

function TOAuthRequest.GetSignableParameters: string;
var
  x: integer;
  parm: string;
begin
  parm := '';
  x := FParameters.IndexOfName('oauth_signature');
  if x <> -1 then
    FParameters.Delete(x);
  for x := 0 to FParameters.Count - 1 do
  begin
    if x = 0 then
    begin
      FParameters.ValueFromIndex[x] := TOAuthUtil.urlEncodeRFC3986(FParameters.ValueFromIndex[x]);
      parm := FParameters.Names[x] + TOAuthUtil.urlEncodeRFC3986('=') +UrlEncode(FParameters.ValueFromIndex[x]);
    end
    else
      parm := parm + TOAuthUtil.urlEncodeRFC3986('&') +
              FParameters.Names[x] + TOAuthUtil.urlEncodeRFC3986('=' + FParameters.ValueFromIndex[x])
  end;
  Result := parm;
end;
 
{ TOAuthUtil }
class function TOAuthUtil.urlDecodeRFC3986(URL: string): string;
begin
  result := URLDecode(URL);
end;
 
class function TOAuthUtil.urlEncodeRFC3986(URL: string): string;
var
  URL1: string;
begin
  URL1 := URLEncode(URL);
  URL1 := StringReplace(URL1, '+', ' ', [rfReplaceAll, rfIgnoreCase]);
  result := URL1;
end;

function Base64Encode_(const Input: TBytes): string;
begin
  Result:=Base64Encode(StringOf(Input));
end;

function TOAuthSignatureMethod_HMAC_SHA1.build_signature(Request: TOAuthRequest;
  Consumer: TOAuthConsumer; Token: TOAuthToken): string;

function EncryptHMACSha1(Input, AKey: string): TBytes;
  begin
    Result:=BytesOf(HMAC_SHA1_EX(Input,AKey));
  end;

{ TOAuthSignatureMethod_HMAC_SHA1 }
function TOAuthSignatureMethod_HMAC_SHA1.build_signature(Request: TOAuthRequest;
  Consumer: TOAuthConsumer; Token: TOAuthToken): string;
var
  parm1, parm: string;
  consec, toksec: string;
begin
  parm1 := Request.GetSignableParameters;
  parm := TOAuthUtil.urlEncodeRFC3986(Request.Scheme) +
          TOAuthUtil.urlEncodeRFC3986(Request.Host) +
          TOAuthUtil.urlEncodeRFC3986(Request.Path);
  if Request.Fields <> '' then
  begin
    parm := parm + '&' + TOAuthUtil.urlEncodeRFC3986(Request.Fields);
    parm := parm +  TOAuthUtil.urlEncodeRFC3986('&') + parm1;
  end
  else
    parm :=  parm + '&' + parm1;
 
  Request.BaseString := 'GET&' + parm;
  if Token <> nil then
  begin
    consec := TOAuthUtil.urlEncodeRFC3986(Consumer.Secret);
    toksec := TOAuthUtil.urlEncodeRFC3986(Token.Secret);
    consec := consec + '&' + toksec;
    Result := Base64Encode_(EncryptHMACSha1(Request.BaseString, consec))
  end
  else
  begin
    consec := TOAuthUtil.urlEncodeRFC3986(Consumer.Secret);
    consec := consec + '&';
    Result := Base64Encode_(EncryptHMACSha1(Request.BaseString, consec));
  end;
end;

function TOAuthRequest.GenerateNonce: string;
begin
  Result := StrMd5(GenerateTimeStamp);
end;

function TTwitter.GETCommand(URL: string): string;
var
  pos: integer;
  HTTP: THTTPCli;
  Stream: TStringStream;
begin
  try
    FConsumer := nil;
    FConsumer := TOAuthConsumer.Create(FKey, FSecret, CallbackURL);
    FRequest := TOAuthRequest.Create(URL);
    FRequest := Request.FromConsumerAndToken(FConsumer, nil, URL);
    FRequest.HTTPURL := URL;
    FToken := TOAuthToken.Create(FOAuth_token, FOAuth_token_secret);
    FRequest := Request.FromConsumerAndToken(FConsumer, FToken, URL);
    FRequest.Sign_Request(HMAC, Consumer, Token);
    pos := AnsiPos('?', URL);
    if pos = 0 then
      URL := URL + '?' + Request.GetString
    else
      URL := URL + '&' + Request.GetString;
    Stream := TStringStream.Create;
    HTTP := THTTPCli.Create(nil);
    HTTP.URL := URL;
    HTTP.RcvdStream := Stream;
    HTTP.Get;
    Result := Stream.DataString;
  finally
    FreeAndNil(HTTP);
    FreeAndNil(Stream);
  end;
end;

function TTwitter.POSTCommand(URL: string; Params: TStringList): string;
var
  pos: integer;
  ah, Key: string;
  aa: TStringList;
  HTTP: THTTPCli;
  Send, Rcv: TStringStream;
begin
  try
    FRequest := TOAuthRequest.Create(URL);
    FToken := TOAuthToken.Create(FOAuth_token, FOAuth_token_secret);
    FRequest := Request.FromConsumerAndToken(FConsumer, FToken, URL);
    FRequest.HTTPURL := URL;
    ah := FRequest.genAuthHeader(Consumer, Token, Params, URL);
    aa := TStringList.Create;
    aa.Clear;
    aa.Add(FRequest.encodeParams(Params, '&', false, true));
    HTTP := THTTPCli.Create(nil);
    HTTP.Options := [];
    Send := TStringStream.Create;
    Rcv := TStringStream.Create;
    Send.WriteString(Trim(aa.Text));
    Send.Position := 0;
    HTTP.Accept := 'text/html';
    HTTP.SendStream := Send;
    HTTP.RcvdStream := Rcv;
    HTTP.RequestVer := '1.1';
    HTTP.OnBeforeHeaderSend := AddCustomHeader;
    FAuthHeader := 'Authorization: ' + ah;
    HTTP.URL := URL;
    HTTP.Post;
    Result:=Rcv.DataString
  finally
    FreeAndNil(aa);
    FreeAndNil(Send);
    FreeAndNil(Rcv);
    FreeAndNil(HTTP);
  end;
end;