通过改进DES加密算法并解决线程安全问题，实现加密性能提升至接近未加密状态的45%-50%，介绍具体实现过程及代码示例。
由于项目需要将日志进行加密，并且合同附件写明是使用DES，不得已而做了下来，经过测试，性能仅为原来没有加密前的九至十分之一，而现成的东西不确定是否为线程安全的，即便是使用DLL库，进行线程分离加载也算大废周章。难耐之下，取来一C++的DES加密单元进行了代码转换，直接将其中公共变量（存在线程安全问题）声明改为threadval，调入程序当中，发现性能还不错，是原来加密库的四至五倍，接近不加密时的45%~50%，多少也算了过得去。下面列出源代码和用例（时间关系，注释都是原来C++单元当中搬过来的）：
unit UnitDES;
...{$ifndef LITTLE_ENDIAN} ...{$define LITTLE_ENDIAN 1}...{$endif}interfaceconst(* 32-bit permutation function P used on the output of the S-boxes *)p32i: array[0..31] of Byte = ( 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25);(* The (in)famous S-boxes *) si: array[0..7,0..63] of Byte =( (* S1 *) (14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8, 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0, 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13), (* S2 *) (15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5, 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15, 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9), (* S3 *) (10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1, 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7, 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12), (* S4 *) (7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9, 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4, 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14), (* S5 *) (2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9, 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6, 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14, 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3), (* S6 *) (12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11, 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8, 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6, 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13), (* S7 *) (4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1, 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6, 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2, 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12), (* S8 *) (13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7, 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2, 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8, 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11));(* bit 0 is left-most in byte *)bytebit: array [0..7] of Integer =( 0200, 0100, 040, 020, 010, 04, 02, 01);nibblebit : array [0..3] of Integer =( 010, 04, 02, 01);(* initial permutation IP *)ip :array[0..63] of Byte =( 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7);(* final permutation IP^-1 *)fp: array[0..63] of Byte =( 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25);(* permuted choice table (key) *)pc1: array[0..55]of Byte =( 57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4);(* number left rotations of pc1 *)totrot: array [0..15] of Byte =( 1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 23, 25, 27, 28);(* permuted choice key (table) *) pc2:array[0..47] of Byte =( 14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32);//varthreadvar(* Lookup tables initialized once only at startup by desinit() *) sp: array [0..7,0..63] of LongWord; (* Combined S and P boxes *) iperm: array [0..15,0..15,0..7] of Byte;(* Initial and final permutations *) fperm: array[0..15,0..15,0..7] of Byte; (* 8 6-bit subkeys for each of 16 rounds, initialized by dessetkey() *) kn: array [0..15,0..7] of Byte; desmode: Integer;function desinit(mode: Integer):Integer;function dessetkey(const key:PByte): Integer;procedure endes(block:PByte);procedure dedes(block:PByte);function spinit: Integer;(*static*)procedure DES_round(num:Integer; block:PLongWord);(*static*)implementation...{$ifdef LITTLE_ENDIAN}(* Byte swap a long *)//function byteswap(x:LongWord):LongWord;//var// cp,CP1:PChar;// tmp:Char;(*register*)//begin// cp := PChar( @x);// Inc(cp,3);// tmp := cp^;// cp1 := cp;// Dec(cp,3);// cp1^ := cp^;// cp^ := tmp;//// Dec(cp1);// Inc(cp);// tmp := cp1^;// cp1^ := cp^;// cp^ := tmp;//// Result := x;//end;//{$else}function byteswap(x:LongWord):LongWord;assembler;asm bswap eaxend;...{$endif} (* LITTLE_ENDIAN *)(* Initialize the lookup table for the combined S and P boxes *)function spinit: Integer;var pbox: array [0..31] of Byte; p, i, s, j, rowcol: Integer; val: longInt;begin (* * Compute pbox, the inverse of p32i. This is easier to work with *) for p := 0 to 32-1 do begin for i := 0 to 32-1 do begin if (p32i[i] - 1 = p) then begin pbox[p] := i; break; end; end; end; for s := 0 to 8 - 1 do begin (* For each S-box *) for i := 0 to 64 - 1 do begin (* For each possible input *) val := 0; (* * The row number is formed from the first and last bits; the * column number is from the middle 4 *) //rowcol := (i and 32) or ((i and 1) ? 16 : 0) or ((i shr 1) and $f); if (i and 1) <> 0 then rowcol := (i and 32) or ( 16 ) or ((i shr 1) and $f) else rowcol := (i and 32) or ( 0) or ((i shr 1) and $f); for j := 0 to 4-1 do begin (* For each output bit *) if (si[s][rowcol] and (8 shr j)) <> 0 then begin val := val or (1 shl (31 - pbox[4 * s + j])); end; end; sp[s][i] := val; end; end; Result := 0;end;(* The nonlinear function f(r,k), the heart of DES *)// unsigned long r; /* 32 bits */// unsigned char subkey[8]; /* 48-bit key for this round */function f( r:LongWord; subkey:PByte):LongWord;(*static*)var rval, rt:LongWord;(*register *)begin (* * Run E(R) ^ K through the combined S & P boxes This code takes * advantage of a convenient regularity in E, namely that each group of 6 * bits in E(R) feeding a single S-box is a contiguous segment of R. *) //rt := (r shr 1) or ((r and 1) ? $80000000 : 0); if (r and 1) <> 0 then rt := (r shr 1) or $80000000 else rt := (r shr 1) or 0; rval := 0; rval :=rval or ( sp[0][((rt shr 26) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[1][((rt shr 22) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[2][((rt shr 18) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[3][((rt shr 14) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[4][((rt shr 10) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[5][((rt shr 6) xor subkey^) and $3f]); Inc(subkey); rval :=rval or ( sp[6][((rt shr 2) xor subkey^) and $3f]); Inc(subkey); //rt := (r shl 1) or ((r and $80000000) ? 1 : 0); if (r and $80000000)<>0 then rt := (r shl 1) or ( 1 ) else rt := (r shl 1) or (0); rval :=rval or sp[7][(rt xor subkey^) and $3f]; result := rval;end;(* Do one DES cipher round *)// int num; /* i.e. the num-th one */// unsigned long *block;procedure DES_round(num:Integer; block:PLongWord);(*static*)var block1:PLongWord;begin // long f(); (* * The rounds are numbered from 0 to 15. On even rounds the right half is * fed to f() and the result exclusive-ORs the left half; on odd rounds * the reverse is done. *) block1 := block; Inc(block1); if (num and 1)<> 0 then begin block1^ :=block1^ xor f(block^, @kn[num]); end else begin block^ :=block^ xor f(block1^, @kn[num]); end;end;(* Allocate space and initialize DES lookup arrays* mode == 0: standard Data Encryption Algorithm* mode == 1: DEA without initial and final permutations for speed* mode == 2: DEA without permutations and with 128-byte key (completely* independent subkeys for each round)*)function desinit(mode: Integer):Integer;procedure iperminit;var l, j, k: Integer;(*register*) i, m: Integer;begin (* Clear the permutation array *) for i := 0 to 16 - 1 do begin for j := 0 to 16-1 do begin for k := 0 to 8-1 do begin iperm[i][j][k] := 0; end; end; end; for i := 0 to 16-1 do (* each input nibble position *) begin for j := 0 to 16-1 do(* each possible input nibble *) begin for k := 0 to 64-1 do begin (* each output bit position *) l := ip[k] - 1; (* where does this bit come from *) if ((l shr 2) <> i) then (* does it come from input posn? *) continue; (* if not, bit k is 0 *) if (0 = (j and nibblebit[l and 3])) then continue; (* any such bit in input? *) m := k and 07; (* which bit is this in the byte *) iperm[i][j][k shr 3] := iperm[i][j][k shr 3] or bytebit[m]; end; end; end;end;procedure fperminit;var l, j, k: Integer;(*register*) i, m: Integer;begin (* Clear the permutation array *) for i := 0 to 16 - 1 do begin for j := 0 to 16-1 do begin for k := 0 to 8-1 do begin fperm[i][j][k] := 0; end; end; end; for i := 0 to 16-1 do (* each input nibble position *) begin for j := 0 to 16-1 do(* each possible input nibble *) begin for k := 0 to 64-1 do begin (* each output bit position *) l := fp[k] - 1; (* where does this bit come from *) if ((l shr 2) <> i) then (* does it come from input posn? *) continue; (* if not, bit k is 0 *) if (0 = (j and nibblebit[l and 3])) then continue; (* any such bit in input? *) m := k and 07; (* which bit is this in the byte *) fperm[i][j][k shr 3] := fperm[i][j][k shr 3] or bytebit[m]; end; end; end;end;begin Result := 0; desmode := mode; spinit(); if (mode = 1) or (mode = 2) then(* No permutations *) Exit; iperminit; fperminit;end;(* Set key (initialize key schedule array) *)// char *key; /* 64 bits (will use only 56) */function dessetkey(const key:PByte): Integer;var pc1m:array [0..55] of Byte; (* place to modify pc1 into *) pcr: array [0..55] of Byte; (* place to rotate pc1 into *) i, j, l:Integer;(*register*) M:integer; Key1:PByte;begin (* * In mode 2, the 128 bytes of subkey are set directly from the user's * key, allowing him to use completely independent subkeys for each * round. Note that the user MUST specify a full 128 bytes. * * I would like to think that this technique gives the NSA a real headache, * but I'm not THAT naive. *) Result := -1; if (desmode = 2) then begin Key1 := Key; for i := 0 to 16-1 do begin for j := 0 to 8-1 do begin kn[i][j] := key1^; Inc(Key1); end; end; Exit; end; (* Clear key schedule *) for i := 0 to 16-1 do begin for j := 0 to 8-1 do begin kn[i][j] := 0; end; end; for j := 0 to 56-1 do begin (* convert pc1 to bits of key *) l := pc1[j] - 1; (* integer bit location *) m := l and 07; (* find bit *) //pc1m[j] := (key[l shr 3] and (* find which key byte l is in *) // bytebit[m]) (* and which bit of that byte *) // ? 1 : 0; (* and store 1-bit result *) if (PByte(Integer(key)+(l shr 3))^ and bytebit[m]) <> 0 then pc1m[j] := 1 else pc1m[j] := 0; end; for i := 0 to 16-1 do begin (* key chunk for each iteration *) for j := 0 to 56-1 do(* rotate pc1 the right amount *) begin //pcr[j] := pc1m[(l = j + totrot[i]) < (j < 28 ? 28 : 56) ? l : l - 28]; l := j + totrot[I]; if J < 28 then begin if l < 28 then begin pcr[j] := pc1m[l]; end else begin pcr[j] := pc1m[l-28]; end; end else begin if l < 56 then begin pcr[j] := pc1m[l]; end else begin pcr[j] := pc1m[l-28]; end; end; end; (* rotate left and right halves independently *) for j := 0 to 48-1 do begin (* select bits individually *) (* check bit that goes to kn[j] *) if (pcr[pc2[j] - 1] <> 0) then begin (* mask it in if it's there *) l := j mod 6; kn[i][j div 6] :=kn[i][j div 6] or (bytebit[l] shr 2); end; end; end; Result := 0;end;(* In-place encryption of 64-bit block *)procedure endes(block:PByte);var i:Integer;(*register*) work:array [0..1] of LongWord; (* Working data storage *) tmp:LongInt;function Ipermute:Integer;(*static*)var i, j:Integer;(*register*) ib,ob:PByte;(*register*) (* ptr to input or output block *) p, q:PByte;(*register*)begin Result := 0; if (iperm[0][0][0] = 0) then begin (* No permutation, just copy *) ib := block; ob := PByte(@work[0]); for i := 8 downto 1 do begin ob^:= ib^; Inc(ib); Inc(ob); end; Exit; end; (* Clear output block *) ob := PByte(@work[0]); for i := 8 downto 1 do begin ob^ := 0; Inc(ob); end; ib := block; J := 0; while j < 16 do begin (* for each input nibble *) ob := PByte(@work[0]); p := @iperm[j][(ib^ shr 4) and 017]; q := @iperm[j + 1][ib^ and 017]; for i := 8 downto 1 do begin (* and each output byte *) ob^ :=ob^ or (p^ or q^); (* OR the masks together *) inc(q); inc(p); Inc(ob); end; Inc(ib); Inc(J,2); end;end;function fpermute:Integer;(*static*)var i, j:Integer;(*register*) ib,ob:PByte;(*register*) (* ptr to input or output block *) p, q:PByte;(*register*)begin Result := 0; if (fperm[0][0][0] = 0) then begin (* No permutation, just copy *) ib := PByte(@work[0]); ob := block; for i := 8 downto 1 do begin ob^:= ib^; Inc(ib); Inc(ob); end; Exit; end; (* Clear output block *) ob := block; for i := 8 downto 1 do begin ob^ := 0; Inc(ob); end; ib := PByte(@work[0]); j := 0; while j < 16 do begin (* for each input nibble *) ob := block; p := @fperm[j][(ib^ shr 4) and 017]; q := @fperm[j + 1][ib^ and 017]; for i := 8 downto 1 do begin (* and each output byte *) ob^ :=ob^ or (p^ or q^); (* OR the masks together *) inc(q); inc(p); Inc(ob); end; Inc(ib); Inc(J,2); end;end;begin Ipermute; (* Initial Permutation *)...{$ifdef LITTLE_ENDIAN} work[0] := byteswap(work[0]); work[1] := byteswap(work[1]);...{$endif} (* LITTLE_ENDIAN *) (* Do the 16 rounds *) for i := 0 to 16-1 do DES_round(i, @work[0]); (* Left/right half swap *) tmp := work[0]; work[0] := work[1]; work[1] := tmp;...{$ifdef LITTLE_ENDIAN} work[0] := byteswap(work[0]); work[1] := byteswap(work[1]);...{$endif} (* LITTLE_ENDIAN *) fpermute; (* Inverse initial * permutation *)end;(* In-place decryption of 64-bit block *)procedure dedes(block:PByte);var I: Integer;(*register*) work: array [0..1] of LongWord; (* Working data storage *) tmp:LongInt;function Ipermute:Integer;(*static*)var i, j:Integer;(*register*) ib,ob:PByte;(*register*) (* ptr to input or output block *) p, q:PByte;(*register*)begin Result := 0; if (iperm[0][0][0] = 0) then begin (* No permutation, just copy *) ib := block; ob := PByte(@work[0]); for i := 8 downto 1 do begin ob^:= ib^; Inc(ib); Inc(ob); end; Exit; end; (* Clear output block *) ob := PByte(@work[0]); for i := 8 downto 1 do begin ob^ := 0; Inc(ob); end; ib := block; J := 0; while j < 16 do begin (* for each input nibble *) ob := PByte(@work[0]); p := @iperm[j][(ib^ shr 4) and 017]; q := @iperm[j + 1][ib^ and 017]; for i := 8 downto 1 do begin (* and each output byte *) ob^ :=ob^ or (p^ or q^); (* OR the masks together *) inc(q); inc(p); Inc(ob); end; Inc(ib); Inc(J,2); end;end;function Fpermute:Integer;(*static*)var i, j:Integer;(*register*) ib,ob:PByte;(*register*) (* ptr to input or output block *) p, q:PByte;(*register*)begin Result := 0; if (fperm[0][0][0] = 0) then begin (* No permutation, just copy *) ib := PByte(@work[0]); ob := block; for i := 8 downto 1 do begin ob^:= ib^; Inc(ib); Inc(ob); end; Exit; end; (* Clear output block *) ob := block; for i := 8 downto 1 do begin ob^ := 0; Inc(ob); end; ib := PByte(@work[0]); J := 0; while j < 16 do begin (* for each input nibble *) ob := block; p := @fperm[j][(ib^ shr 4) and 017]; q := @fperm[j + 1][ib^ and 017]; for i := 8 downto 1 do begin (* and each output byte *) ob^ :=ob^ or (p^ or q^); (* OR the masks together *) inc(q); inc(p); Inc(ob); end; Inc(ib); Inc(J,2); end;end;begin Ipermute; (* Initial permutation *)...{$ifdef LITTLE_ENDIAN} work[0] := byteswap(work[0]); work[1] := byteswap(work[1]);...{$endif} (* LITTLE_ENDIAN *) (* Left/right half swap *) tmp := work[0]; work[0] := work[1]; work[1] := tmp; (* Do the 16 rounds in reverse order *) for i := 15 downto 0 do DES_round(i, @work[0]);...{$ifdef LITTLE_ENDIAN} work[0] := byteswap(work[0]); work[1] := byteswap(work[1]);...{$endif} (* LITTLE_ENDIAN *) Fpermute; (* Inverse initial * permutation *)end;end.uses UnitDES;procedure TForm1.btnTestClick(Sender: TObject);var sIn,sOutHex,sKey:String; NewLen,I: Integer; block :PByte; P,P1:PChar; B,B1:Byte;begin sIn := '测试字符串'; sKey := '这是密钥'; desinit(0); I := Length(sKey); SetLength(sKey,8); //调整密钥为8位 if I < 8 then //填充密钥 FillChar(PChar(Integer(PChar(sKey))+I)^,8-I,100); I := Length(sIn); if (I mod 8 )<>0 then begin //调整串长为8的倍数 NewLen := ((I div 8) + 1) * 8; SetLength(sIn,NewLen); //置串结束符(这里是串加密 PChar(Integer(PChar(sIn))+I)^ := #0; end; //初始化密钥 dessetkey(PByte(PChar(sKey))); block := Pointer(sIn); NewLen := Length(sIn); while( NewLen > 0 ) do begin //加密 endes( PByte(block)); Dec(NewLen,8); Inc(block,8); end; //十六进制转换 SetString(sOutHex,Nil,Length(sIn) * 2); P := PChar(sIn); P1 := PChar(sOutHex); for I := 0 to Length(sIn) - 1 do begin B := Byte(P^); B1 := ((B shr 4) and $f); case B1 of 0..9: P1^ := Chr(B1 + 48) else P1^ := Chr(B1 + 65 - 10); end; Inc(P1); B1 := (B and $f); case B1 of 0..9: P1^ := Chr(B1 + 48) else P1^ := Chr(B1 + 65 - 10); end; Inc(P1); Inc(P); end; ShowMessage(sOutHex); //初始化密钥 dessetkey(PByte(PChar(sKey))); NewLen := Length(sIn); block := Pointer(sIn); while( NewLen > 0 ) do begin //解密 dedes(PByte(block)); Dec(NewLen, 8); Inc(block, 8); end; SetLength(sIn,strlen(PChar(sIn))); ShowMessage(sIn);end;
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