Алгоритм MD5

function md5(s:string):string;
var a:array[0..15] of byte;
i:integer;

lenhi, lenlo: longword;
index: dword;
hashbuffer: array[0..63] of byte;
currenthash: array[0..3] of dword;

procedure burn;
begin
lenhi:= 0; lenlo:= 0;
index:= 0;
fillchar(hashbuffer,sizeof(hashbuffer),0);
fillchar(currenthash,sizeof(currenthash),0);
end;

procedure init;
begin
burn;
currenthash[0]:= $67452301;
currenthash[1]:= $efcdab89;
currenthash[2]:= $98badcfe;
currenthash[3]:= $10325476;
end;

function lrot32(a, b: longword): longword;
begin
result:= (a shl b) or (a shr (32-b));
end;

procedure compress;
var
data: array[0..15] of dword;
a, b, c, d: dword;
begin
move(hashbuffer,data,sizeof(data));
a:= currenthash[0];
b:= currenthash[1];
c:= currenthash[2];
d:= currenthash[3];

a:= b + lrot32(a + (d xor (b and (c xor d))) + data[ 0] + $d76aa478,7);
d:= a + lrot32(d + (c xor (a and (b xor c))) + data[ 1] + $e8c7b756,12);
c:= d + lrot32(c + (b xor (d and (a xor b))) + data[ 2] + $242070db,17);
b:= c + lrot32(b + (a xor (c and (d xor a))) + data[ 3] + $c1bdceee,22);
a:= b + lrot32(a + (d xor (b and (c xor d))) + data[ 4] + $f57c0faf,7);
d:= a + lrot32(d + (c xor (a and (b xor c))) + data[ 5] + $4787c62a,12);
c:= d + lrot32(c + (b xor (d and (a xor b))) + data[ 6] + $a8304613,17);
b:= c + lrot32(b + (a xor (c and (d xor a))) + data[ 7] + $fd469501,22);
a:= b + lrot32(a + (d xor (b and (c xor d))) + data[ 8] + $698098d8,7);
d:= a + lrot32(d + (c xor (a and (b xor c))) + data[ 9] + $8b44f7af,12);
c:= d + lrot32(c + (b xor (d and (a xor b))) + data[10] + $ffff5bb1,17);
b:= c + lrot32(b + (a xor (c and (d xor a))) + data[11] + $895cd7be,22);
a:= b + lrot32(a + (d xor (b and (c xor d))) + data[12] + $6b901122,7);
d:= a + lrot32(d + (c xor (a and (b xor c))) + data[13] + $fd987193,12);
c:= d + lrot32(c + (b xor (d and (a xor b))) + data[14] + $a679438e,17);
b:= c + lrot32(b + (a xor (c and (d xor a))) + data[15] + $49b40821,22);

a:= b + lrot32(a + (c xor (d and (b xor c))) + data[ 1] + $f61e2562,5);
d:= a + lrot32(d + (b xor (c and (a xor b))) + data[ 6] + $c040b340,9);
c:= d + lrot32(c + (a xor (b and (d xor a))) + data[11] + $265e5a51,14);
b:= c + lrot32(b + (d xor (a and (c xor d))) + data[ 0] + $e9b6c7aa,20);
a:= b + lrot32(a + (c xor (d and (b xor c))) + data[ 5] + $d62f105d,5);
d:= a + lrot32(d + (b xor (c and (a xor b))) + data[10] + $02441453,9);
c:= d + lrot32(c + (a xor (b and (d xor a))) + data[15] + $d8a1e681,14);
b:= c + lrot32(b + (d xor (a and (c xor d))) + data[ 4] + $e7d3fbc8,20);
a:= b + lrot32(a + (c xor (d and (b xor c))) + data[ 9] + $21e1cde6,5);
d:= a + lrot32(d + (b xor (c and (a xor b))) + data[14] + $c33707d6,9);
c:= d + lrot32(c + (a xor (b and (d xor a))) + data[ 3] + $f4d50d87,14);
b:= c + lrot32(b + (d xor (a and (c xor d))) + data[ 8] + $455a14ed,20);
a:= b + lrot32(a + (c xor (d and (b xor c))) + data[13] + $a9e3e905,5);
d:= a + lrot32(d + (b xor (c and (a xor b))) + data[ 2] + $fcefa3f8,9);
c:= d + lrot32(c + (a xor (b and (d xor a))) + data[ 7] + $676f02d9,14);
b:= c + lrot32(b + (d xor (a and (c xor d))) + data[12] + $8d2a4c8a,20);

a:= b + lrot32(a + (b xor c xor d) + data[ 5] + $fffa3942,4);
d:= a + lrot32(d + (a xor b xor c) + data[ 8] + $8771f681,11);
c:= d + lrot32(c + (d xor a xor b) + data[11] + $6d9d6122,16);
b:= c + lrot32(b + (c xor d xor a) + data[14] + $fde5380c,23);
a:= b + lrot32(a + (b xor c xor d) + data[ 1] + $a4beea44,4);
d:= a + lrot32(d + (a xor b xor c) + data[ 4] + $4bdecfa9,11);
c:= d + lrot32(c + (d xor a xor b) + data[ 7] + $f6bb4b60,16);
b:= c + lrot32(b + (c xor d xor a) + data[10] + $bebfbc70,23);
a:= b + lrot32(a + (b xor c xor d) + data[13] + $289b7ec6,4);
d:= a + lrot32(d + (a xor b xor c) + data[ 0] + $eaa127fa,11);
c:= d + lrot32(c + (d xor a xor b) + data[ 3] + $d4ef3085,16);
b:= c + lrot32(b + (c xor d xor a) + data[ 6] + $04881d05,23);
a:= b + lrot32(a + (b xor c xor d) + data[ 9] + $d9d4d039,4);
d:= a + lrot32(d + (a xor b xor c) + data[12] + $e6db99e5,11);
c:= d + lrot32(c + (d xor a xor b) + data[15] + $1fa27cf8,16);
b:= c + lrot32(b + (c xor d xor a) + data[ 2] + $c4ac5665,23);

a:= b + lrot32(a + (c xor (b or (not d))) + data[ 0] + $f4292244,6);
d:= a + lrot32(d + (b xor (a or (not c))) + data[ 7] + $432aff97,10);
c:= d + lrot32(c + (a xor (d or (not b))) + data[14] + $ab9423a7,15);
b:= c + lrot32(b + (d xor (c or (not a))) + data[ 5] + $fc93a039,21);
a:= b + lrot32(a + (c xor (b or (not d))) + data[12] + $655b59c3,6);
d:= a + lrot32(d + (b xor (a or (not c))) + data[ 3] + $8f0ccc92,10);
c:= d + lrot32(c + (a xor (d or (not b))) + data[10] + $ffeff47d,15);
b:= c + lrot32(b + (d xor (c or (not a))) + data[ 1] + $85845dd1,21);
a:= b + lrot32(a + (c xor (b or (not d))) + data[ 8] + $6fa87e4f,6);
d:= a + lrot32(d + (b xor (a or (not c))) + data[15] + $fe2ce6e0,10);
c:= d + lrot32(c + (a xor (d or (not b))) + data[ 6] + $a3014314,15);
b:= c + lrot32(b + (d xor (c or (not a))) + data[13] + $4e0811a1,21);
a:= b + lrot32(a + (c xor (b or (not d))) + data[ 4] + $f7537e82,6);
d:= a + lrot32(d + (b xor (a or (not c))) + data[11] + $bd3af235,10);
c:= d + lrot32(c + (a xor (d or (not b))) + data[ 2] + $2ad7d2bb,15);
b:= c + lrot32(b + (d xor (c or (not a))) + data[ 9] + $eb86d391,21);

inc(currenthash[0],a);
inc(currenthash[1],b);
inc(currenthash[2],c);
inc(currenthash[3],d);
index:= 0;
fillchar(hashbuffer,sizeof(hashbuffer),0);
end;


procedure update(const buffer; size: longword);
var
pbuf: ^byte;
begin
inc(lenhi,size shr 29);
inc(lenlo,size*8);
if lenlo< (size*8) then
inc(lenhi);

pbuf:= @buffer;
while size> 0 do
begin
if (sizeof(hashbuffer)-index)<= dword(size) then
begin
move(pbuf^,hashbuffer[index],sizeof(hashbuffer)-index);
dec(size,sizeof(hashbuffer)-index);
inc(pbuf,sizeof(hashbuffer)-index);
compress;
end
else
begin
move(pbuf^,hashbuffer[index],size);
inc(index,size);
size:= 0;
end;
end;
end;

procedure final(var digest);
begin
hashbuffer[index]:= $80;
if index>= 56 then compress;
pdword(@hashbuffer[56])^:= lenlo;
pdword(@hashbuffer[60])^:= lenhi;
compress;
move(currenthash,digest,sizeof(currenthash));
burn;
end;


begin
init;
update(s[1],length(s));
final(a);
result:='';
for i:=0 to 15 do
result:=result+inttohex(a[i],0);
burn;
end;