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const

  Base64Table =

    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

function Base64Decode(cStr: string): string;

var

  ResStr: string;

  DecStr: string;

  RecodeLine: array[1..76] of byte;

  f1, f2: word;

  l: integer;

begin

  l := length(cStr);

  ResStr := '';

  for f1 := 1 to l do

    if cStr[f1] = '=' then

      RecodeLine[f1] := 0

    else

      RecodeLine[f1] := pos(cStr[f1], Base64Table) - 1;

  f1 := 1;

  while f1 < length(cStr) do

  begin

    DecStr := chr(byte(RecodeLine[f1] shl 2) + RecodeLine[f1 + 1] shr 4) +

      chr(byte(RecodeLine[f1 + 1] shl 4) + RecodeLine[f1 + 2] shr 2) +

      chr(byte(RecodeLine[f1 + 2] shl 6) + RecodeLine[f1 + 3]);

    ResStr := ResStr + DecStr;

    inc(f1, 4);

  end;

  Base64Decode := ResStr;

end;