？？？？菜鸟想加密和解密长度为2000个字节左右的文本，有什么好函数吗？一定要能解密啊。
解决方案 »
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private
function Add(X, Y: Integer): Integer;
function Rol(X, n: Integer): Integer;
function Cvt(S: ShortString): TIntData;
function Cmn(q, a, b, x, s, t: Integer): Integer;
function rHex(X: Integer): ShortString;
function ff(a, b, c, d, x, s, t: Integer): Integer;
function gg(a, b, c, d, x, s, t: Integer): Integer;
function hh(a, b, c, d, x, s, t: Integer): Integer;
function ii(a, b, c, d, x, s, t: Integer): Integer;
public
function Md5(S: ShortString): ShortString;
end;implementationfunction TMD5Word.Add(X, Y: Integer): Integer;
var
lsw, msw: Integer;
begin
//Result := X + Y;
//Add integers, wrapping at 2^32. This uses 16-bit operations internally
//to work around bugs in some JS interpreters.
lsw := (X and $ffff) + (Y and $ffff);
msw := (X shr 16) + (Y shr 16) + (lsw shr 16);
Result := (msw shl 16) or (lsw and $ffff);
end;function TMD5Word.Rol(X, n: Integer): Integer;
begin
//Bitwise rotate a 32-bit number to the left
Result := (X shl n) or (X shr (32 - n));
end;function TMD5Word.Cmn(q, a, b, x, s, t: Integer): Integer;
begin
Result := Add(Rol(Add(Add(a, q), Add(x, t)), s), b);
end;function TMD5Word.Cvt(S: ShortString): TIntData;
var
nblk: Integer;
len, i: Integer;
begin
len := Length(S);
nblk := ((len + 8) shr 6) + 1;
SetLength(Result, nblk * 16);
for i := 0 to (nblk * 16 - 1) do
Result[i] := 0;
for i := 0 to len - 1 do
Result[i shr 2] := Result[i shr 2] or
(Ord(S[i + 1]) shl ((i mod 4) * 8));
Result[len shr 2] := Result[len shr 2] or
($80 shl ((len mod 4) * 8));
Result[nblk * 16 - 2] := len * 8;
end;function TMD5Word.rHex(X: Integer): ShortString;
const
HexChs: ShortString = '0123456789abcdef';
var
i: Integer;
begin
SetLength(Result, 8);
//for i := 1 to 8 do
// Result[i] := HexChs[(X shr ((8 - i) shl 2)) and $f + 1];
//转换为16进制的表示方法和IntToHex的不同
for i := 0 to 3 do
begin
Result[i * 2 + 1] := HexChs[(X shr (i * 8 + 4)) and $f + 1];
Result[i * 2 + 2] := HexChs[(X shr (i * 8)) and $f + 1];
end;
end;function TMD5Word.ff(a, b, c, d, x, s, t: Integer): Integer;
begin
Result := Cmn((b and c) or (not b and d), a, b, x, s, t);
end;function TMD5Word.gg(a, b, c, d, x, s, t: Integer): Integer;
begin
Result := Cmn((b and d) or (c and not d), a, b, x, s, t);
end;function TMD5Word.hh(a, b, c, d, x, s, t: Integer): Integer;
begin
Result := Cmn(b xor c xor d, a, b, x, s, t);
end;function TMD5Word.ii(a, b, c, d, x, s, t: Integer): Integer;
begin
Result := Cmn(c xor (b or not d), a, b, x, s, t);
end;function TMD5Word.Md5(S: ShortString): ShortString;
var
x: TIntData;
a, b, c, d: Integer;
olda, oldb, oldc, oldd: Integer;
len, i: Integer;
begin
x := Cvt(S);
len := Length(x);
a := 1732584193;
b := -271733879;
c := -1732584194;
d := 271733878; i := 0;
while i < len do
begin
olda := a;
oldb := b;
oldc := c;
oldd := d; a := ff(a, b, c, d, x[i+ 0], 7 , -680876936);
d := ff(d, a, b, c, x[i+ 1], 12, -389564586);
c := ff(c, d, a, b, x[i+ 2], 17, 606105819);
b := ff(b, c, d, a, x[i+ 3], 22, -1044525330);
a := ff(a, b, c, d, x[i+ 4], 7 , -176418897);
d := ff(d, a, b, c, x[i+ 5], 12, 1200080426);
c := ff(c, d, a, b, x[i+ 6], 17, -1473231341);
b := ff(b, c, d, a, x[i+ 7], 22, -45705983);
a := ff(a, b, c, d, x[i+ 8], 7 , 1770035416);
d := ff(d, a, b, c, x[i+ 9], 12, -1958414417);
c := ff(c, d, a, b, x[i+10], 17, -42063);
b := ff(b, c, d, a, x[i+11], 22, -1990404162);
a := ff(a, b, c, d, x[i+12], 7 , 1804603682);
d := ff(d, a, b, c, x[i+13], 12, -40341101);
c := ff(c, d, a, b, x[i+14], 17, -1502002290);
b := ff(b, c, d, a, x[i+15], 22, 1236535329); a := gg(a, b, c, d, x[i+ 1], 5 , -165796510);
d := gg(d, a, b, c, x[i+ 6], 9 , -1069501632);
c := gg(c, d, a, b, x[i+11], 14, 643717713);
b := gg(b, c, d, a, x[i+ 0], 20, -373897302);
a := gg(a, b, c, d, x[i+ 5], 5 , -701558691);
d := gg(d, a, b, c, x[i+10], 9 , 38016083);
c := gg(c, d, a, b, x[i+15], 14, -660478335);
b := gg(b, c, d, a, x[i+ 4], 20, -405537848);
a := gg(a, b, c, d, x[i+ 9], 5 , 568446438);
d := gg(d, a, b, c, x[i+14], 9 , -1019803690);
c := gg(c, d, a, b, x[i+ 3], 14, -187363961);
b := gg(b, c, d, a, x[i+ 8], 20, 1163531501);
a := gg(a, b, c, d, x[i+13], 5 , -1444681467);
d := gg(d, a, b, c, x[i+ 2], 9 , -51403784);
c := gg(c, d, a, b, x[i+ 7], 14, 1735328473);
b := gg(b, c, d, a, x[i+12], 20, -1926607734); a := hh(a, b, c, d, x[i+ 5], 4 , -378558);
d := hh(d, a, b, c, x[i+ 8], 11, -2022574463);
c := hh(c, d, a, b, x[i+11], 16, 1839030562);
b := hh(b, c, d, a, x[i+14], 23, -35309556);
a := hh(a, b, c, d, x[i+ 1], 4 , -1530992060);
d := hh(d, a, b, c, x[i+ 4], 11, 1272893353);
c := hh(c, d, a, b, x[i+ 7], 16, -155497632);
b := hh(b, c, d, a, x[i+10], 23, -1094730640);
a := hh(a, b, c, d, x[i+13], 4 , 681279174);
d := hh(d, a, b, c, x[i+ 0], 11, -358537222);
c := hh(c, d, a, b, x[i+ 3], 16, -722521979);
b := hh(b, c, d, a, x[i+ 6], 23, 76029189);
a := hh(a, b, c, d, x[i+ 9], 4 , -640364487);
d := hh(d, a, b, c, x[i+12], 11, -421815835);
c := hh(c, d, a, b, x[i+15], 16, 530742520);
b := hh(b, c, d, a, x[i+ 2], 23, -995338651); a := ii(a, b, c, d, x[i+ 0], 6 , -198630844);
d := ii(d, a, b, c, x[i+ 7], 10, 1126891415);
c := ii(c, d, a, b, x[i+14], 15, -1416354905);
b := ii(b, c, d, a, x[i+ 5], 21, -57434055);
a := ii(a, b, c, d, x[i+12], 6 , 1700485571);
d := ii(d, a, b, c, x[i+ 3], 10, -1894986606);
c := ii(c, d, a, b, x[i+10], 15, -1051523);
b := ii(b, c, d, a, x[i+ 1], 21, -2054922799);
a := ii(a, b, c, d, x[i+ 8], 6 , 1873313359);
d := ii(d, a, b, c, x[i+15], 10, -30611744);
c := ii(c, d, a, b, x[i+ 6], 15, -1560198380);
b := ii(b, c, d, a, x[i+13], 21, 1309151649);
a := ii(a, b, c, d, x[i+ 4], 6 , -145523070);
d := ii(d, a, b, c, x[i+11], 10, -1120210379);
c := ii(c, d, a, b, x[i+ 2], 15, 718787259);
b := ii(b, c, d, a, x[i+ 9], 21, -343485551); a := add(a, olda);
b := add(b, oldb);
c := add(c, oldc);
d := add(d, oldd);
i := i + 16;
end;
Result := rHex(a) + rHex(b) + rHex(c) + rHex(d);
end;end.
var
SrcLen, Times, i: integer;
x1, x2, x3, x4, xt: byte;begin
Result := '';
SrcLen := Length(Source);
Times := SrcLen div 4; for i := 0 to Times - 1 do
begin
x1 := FindInTable(Source[1 + i * 4]);
x2 := FindInTable(Source[2 + i * 4]);
x3 := FindInTable(Source[3 + i * 4]);
x4 := FindInTable(Source[4 + i * 4]);
x1 := x1 shl 2;
xt := x2 shr 4;
x1 := x1 or xt;
x2 := x2 shl 4;
Result := Result + chr(x1);
if x3 = 64 then break;
xt := x3 shr 2;
x2 := x2 or xt;
x3 := x3 shl 6;
result := Result + chr(x2);
if x4 = 64 then break;
x3 := x3 or x4;
Result := Result + chr(x3);
end;
end;function TBase64Manage.EncodeBase64(Source: String): String; //base64 编码
var
Times, LenSrc, i: integer;
x1, x2, x3, x4: char;
xt: byte;
begin
Result := '';
LenSrc := Length(Source);
if (LenSrc mod 3) = 0 then
Times := LenSrc div 3
else
Times:=LenSrc div 3 + 1; for i := 0 to times - 1 do
begin
if LenSrc >= (3 + i * 3) then
begin
x1 := BaseTable[(ord(Source[1 + i * 3]) shr 2) + 1];
xt := (ord(Source[1 + i * 3]) shl 4) and 48;
xt := xt or (ord(Source[2 + i * 3]) shr 4);
x2 := BaseTable[xt + 1];
xt := (Ord(Source[2 + i * 3]) shl 2) and 60;
xt := xt or (ord(Source[3 + i * 3]) shr 6);
x3 := BaseTable[xt + 1];
xt := (ord(Source[3 + i * 3]) and 63);
x4 := BaseTable[xt + 1];
end
else
if LenSrc >= (2 + i * 3) then
begin
x1 := BaseTable[(ord(Source[1 + i * 3]) shr 2) + 1];
xt := (ord(Source[1 + i * 3]) shl 4) and 48;
xt := xt or (ord(Source[2 + i * 3]) shr 4);
x2 := BaseTable[xt + 1];
xt := (ord(Source[2 + i * 3]) shl 2) and 60;
x3 := BaseTable[xt + 1];
x4 := '=';
end
else
begin
x1 := BaseTable[(ord(Source[1 + i * 3]) shr 2) + 1];
xt := (ord(Source[1 + i * 3]) shl 4) and 48;
x2 := BaseTable[xt + 1];
x3 := '=';
x4 := '=';
end;
Result := result + x1 + x2 + x3 + x4;
end;
end;