Decoding base64 adds extra spaces

Question

I am working in Delphi XE2 I am converting base64 byte array to string using this

TEncoding.UTF7.GetString(byte1)

Then decoding string into byte array using this function

function Base64Decode(const EncodedText: string): TBytes;
var
  DecodedStm: TBytesStream;
  Decoder: TIdDecoderMIME;
begin
  Decoder := TIdDecoderMIME.Create(nil);
  try
    DecodedStm := TBytesStream.Create;
    try
      Decoder.DecodeBegin(DecodedStm);
      Decoder.Decode(EncodedText);
      Decoder.DecodeEnd;
      Result := DecodedStm.Bytes;
    finally
      DecodedStm.Free;
    end;
  finally
    Decoder.Free;
  end;
end;

But input string length is 400 and after decode its byte array length is 8192.

Somewhere it is adding extra spaces... any suggestion as what I'm doing wrong?

Edit...

this is base64 of my data send from c# through tcp to delphi XE2 app string length = 400

TVpQAAIAAAAEAA8A//8AALgAAAAAAAAAQAAaAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAALoQAA4ftAnNIbgBTM0hkJBUaGlzIHByb2dyYW0gbXVzdCBiZSBydW4gdW5kZXIgV2luMzINCiQ3AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFBFAABMAQgAGV5CKgAAAAAAAAAA4ACOgQsBAhkArAoAAMQCAAAAAAAwugoA

i receive TBytes in my delphi app when i convert TBytes to string following comes

Tbytes to UTF-7 string string length = 401

TVpQAAIAAAAEAA8A//8AALgAAAAAAAAAQAAaAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAALoQAA4ftAnNIbgBTM0hkJBUaGlzIHByb2dyYW0gbXVzdCBiZSBydW4gdW5kZXIgV2luMzINCiQ3AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA‘AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFBFAABMAQgAGV5CKgAAAAAAAAAA4ACOgQsBAhkArAoAAMQCAAAAAAAwugoA

TByte to UTF-8 String string length= 0 ( ZERO)

TByte to ANSI String string length= 401

TVpQAAIAAAAEAA8A//8AALgAAAAAAAAAQAAaAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAALoQAA4ftAnNIbgBTM0hkJBUaGlzIHByb2dyYW0gbXVzdCBiZSBydW4gdW5kZXIgV2luMzINCiQ3AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA‘AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFBFAABMAQgAGV5CKgAAAAAAAAAA4ACOgQsBAhkArAoAAMQCAAAAAAAwugoA

there is 1 extra bit is comming in between but i dont know why it is comming.

kindly advice am i doing any thing wrong.

Answer 1

You can add one line to get the length you are expecting:

function Base64Decode(const EncodedText: string): TBytes;
var
  DecodedStm: TBytesStream;
  Decoder: TIdDecoderMIME;
begin
  Decoder := TIdDecoderMIME.Create(nil);
  try
    DecodedStm := TBytesStream.Create;
    try
      Decoder.DecodeBegin(DecodedStm);
      Decoder.Decode(EncodedText);
      Decoder.DecodeEnd;
      Result := DecodedStm.Bytes;
      SetLength(Result, DecodedStm.Size);  // add this line
    finally
      DecodedStm.Free;
    end;
  finally
    Decoder.Free;
  end;
end;