function md5(st: AnsiString): string;
var D: TIdBytes;
    i: integer;
    S: TMemoryStream;
    Hash, Hash2: TIdBytes;
    d5: TIdHashMessageDigest5;
    st1: string;
begin
Result := '';
S:= TMemoryStream.Create;
d5:= TIdHashMessageDigest5.Create;
try
 Hash:= d5.HashString(st, IndyTextEncoding(encUTF16LE));
 WriteStringToStream(S, st, -1, 1, IndyTextEncoding(encUTF16LE));
 Hash2:= d5.HashStream(S);
 Result:= ToHex2(Hash);
 Result:= ToHex2(Hash2);
finally
d5.Free;
S.Free;
end;
end;

WriteStringToStream

ToHex

function md5(St: String): string;
var D: array of byte;
    i: integer;
    S: TMemoryStream;
begin
Result := '';
S:= TMemoryStream.Create;
SetLength(D, Length(St)*2);
for i:= 0 to Length(St) - 1 do begin
 D[i*2]:= Byte(St[i+1]);
 D[i*2+1]:= $0;
end;
S.WriteBuffer(D[0], Length(St)*2);
S.Position:=0;
with TIdHashMessageDigest5.Create do
try
 Result := UpperCase(AsHex(HashValue(s)));
finally
Free;
S.Free;
end;
end;

unit CryptMod;

interface

Uses
 System.SysUtils, DCPMD5;

function CheckHash(hash: AnsiString; l: integer): boolean;
function DigestToTxt(Digest: Array of byte): AnsiString;
function GetMD5Hash(AStrData: AnsiString): AnsiString;

implementation

function CheckHash(hash: AnsiString; l: integer): boolean;
var sh: set of AnsiChar;
    i: integer;
begin
 Result := false;
 sh := ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','a','b','c','d' ,'e','f'];
 if Length(hash) <> l then Exit;
 for i:=1 to Length(hash) do
   if Not (hash[i] in sh) then Exit;
 result := True;
end;

function DigestToTxt(Digest: Array of byte): AnsiString;
var i : integer;
begin
 for i := 0 to Length(Digest) -1 do Result := Result + IntToHex(Digest[i], 2);
end;

function GetMD5Hash(AStrData: AnsiString): AnsiString;
var MD5: TDCP_md5;
   Digest: array [0..15] of byte;
begin
 try
   MD5 := TDCP_md5.Create(Nil);
   MD5.Init;
   MD5.UpdateStr(AStrData);
   MD5.Final(Digest);
   Result := DigestToTxt(Digest);
 finally
   MD5.Free;
 end;
end;

end.