最稳妥和最不安全的办法是提供两种版本:试用版和完整版。当用户注册了你的软件之后,他们就得到一个url去下载完整版本。完整版是没有任何限制的,所以软件是否被非法使用就完全依赖于用户的诚实,唯一的约束就是只用注册用户才能得到技术支持。我不使用这种方法,因为周围有太多的不诚实的用户,会造成注册量太少。
最后是上一个方法的改良。注册码还是基于版本号,用户可以继续使用老的注册码来进行小的升级,但版本的大改动就需要用户重新注册了。当然你可以不要用户为版本的升级付费,但这是一个可以选择的方案。
我是一个电子工程师,在通讯行业里需要一种方法来确定传输的数据是无误的,一般的方法就是crc。crc已经使用了20年,我不知道crc出现的确切时间,但我知道它一直工作的很好。如果你想知道更多的crc知识,请参考'a painless guide to crc error detection algorithms',作者:ross n. williams,下载地址: http://www.ross.net 。
因此我使用32位的crc算法得出8位的注册码,有个问题:如果用于运算的字符串没有进行任何的加密就太简单了。所以我使用delphi的加密过程加密一下字符串,然后用于运算的字符串就足够复杂了。
unit registration;
{------------------------------------------------------------------------------}
interface
uses
sysutils;
function mod95(pnval : integer): integer; forward;
function sslencode(pcname: string; pccompany: string; pcapptitle: string; pcmajor: string): string; forward;
function sslgeneratekey(pcname, pccompany, pcapplication, pcmajor : string) : string; forward;
function sslcrypt(pcstring : pchar; pnseed : integer = 0) : string ; forward
function crcexecute(pcstring : string) : string ; forward;
var
gnkey : integer;
gnsalt : integer;
{------------------------------------------------------------------------------}
implementation
const
null_string = '';
const crctable : array [0..255] of longword =(
$00000000, $77073096, $ee0e612c, $990951ba,
$076dc419, $706af48f, $e963a535, $9e6495a3,
$0edb8832, $79dcb8a4, $e0d5e91e, $97d2d988,
$09b64c2b, $7eb17cbd, $e7b82d07, $90bf1d91,
$1db71064, $6ab020f2, $f3b97148, $84be41de,
$1adad47d, $6ddde4eb, $f4d4b551, $83d385c7,
$136c9856, $646ba8c0, $fd62f97a, $8a65c9ec,
$14015c4f, $63066cd9, $fa0f3d63, $8d080df5,
$3b6e20c8, $4c69105e, $d56041e4, $a2677172,
$3c03e4d1, $4b04d447, $d20d85fd, $a50ab56b,
$35b5a8fa, $42b2986c, $dbbbc9d6, $acbcf940,
$32d86ce3, $45df5c75, $dcd60dcf, $abd13d59,
$26d930ac, $51de003a, $c8d75180, $bfd06116,
$21b4f4b5, $56b3c423, $cfba9599, $b8bda50f,
$2802b89e, $5f058808, $c60cd9b2, $b10be924,
$2f6f7c87, $58684c11, $c1611dab, $b6662d3d,
$76dc4190, $01db7106, $98d220bc, $efd5102a,
$71b18589, $06b6b51f, $9fbfe4a5, $e8b8d433,
$7807c9a2, $0f00f934, $9609a88e, $e10e9818,
$7f6a0dbb, $086d3d2d, $91646c97, $e6635c01,
$6b6b51f4, $1c6c6162, $856530d8, $f262004e,
$6c0695ed, $1b01a57b, $8208f4c1, $f50fc457,
$65b0d9c6, $12b7e950, $8bbeb8ea, $fcb9887c,
$62dd1ddf, $15da2d49, $8cd37cf3, $fbd44c65,
$4db26158, $3ab551ce, $a3bc0074, $d4bb30e2,
$4adfa541, $3dd895d7, $a4d1c46d, $d3d6f4fb,
$4369e96a, $346ed9fc, $ad678846, $da60b8d0,
$44042d73, $33031de5, $aa0a4c5f, $dd0d7cc9,
$5005713c, $270241aa, $be0b1010, $c90c2086,
$5768b525, $206f85b3, $b966d409, $ce61e49f,
$5edef90e, $29d9c998, $b0d09822, $c7d7a8b4,
$59b33d17, $2eb40d81, $b7bd5c3b, $c0ba6cad,
$edb88320, $9abfb3b6, $03b6e20c, $74b1d29a,
$ead54739, $9dd277af, $04db2615, $73dc1683,
$e3630b12, $94643b84, $0d6d6a3e, $7a6a5aa8,
$e40ecf0b, $9309ff9d, $0a00ae27, $7d079eb1,
$f00f9344, $8708a3d2, $1e01f268, $6906c2fe,
$f762575d, $806567cb, $196c3671, $6e6b06e7,
$fed41b76, $89d32be0, $10da7a5a, $67dd4acc,
$f9b9df6f, $8ebeeff9, $17b7be43, $60b08ed5,
$d6d6a3e8, $a1d1937e, $38d8c2c4, $4fdff252,
$d1bb67f1, $a6bc5767, $3fb506dd, $48b2364b,
$d80d2bda, $af0a1b4c, $36034af6, $41047a60,
$df60efc3, $a867df55, $316e8eef, $4669be79,
$cb61b38c, $bc66831a, $256fd2a0, $5268e236,
$cc0c7795, $bb0b4703, $220216b9, $5505262f,
$c5ba3bbe, $b2bd0b28, $2bb45a92, $5cb36a04,
$c2d7ffa7, $b5d0cf31, $2cd99e8b, $5bdeae1d,
$9b64c2b0, $ec63f226, $756aa39c, $026d930a,
$9c0906a9, $eb0e363f, $72076785, $05005713,
$95bf4a82, $e2b87a14, $7bb12bae, $0cb61b38,
$92d28e9b, $e5d5be0d, $7cdcefb7, $0bdbdf21,
$86d3d2d4, $f1d4e242, $68ddb3f8, $1fda836e,
$81be16cd, $f6b9265b, $6fb077e1, $18b74777,
$88085ae6, $ff0f6a70, $66063bca, $11010b5c,
$8f659eff, $f862ae69, $616bffd3, $166ccf45,
$a00ae278, $d70dd2ee, $4e048354, $3903b3c2,
$a7672661, $d06016f7, $4969474d, $3e6e77db,
$aed16a4a, $d9d65adc, $40df0b66, $37d83bf0,
$a9bcae53, $debb9ec5, $47b2cf7f, $30b5ffe9,
$bdbdf21c, $cabac28a, $53b39330, $24b4a3a6,
$bad03605, $cdd70693, $54de5729, $23d967bf,
$b3667a2e, $c4614ab8, $5d681b02, $2a6f2b94,
$b40bbe37, $c30c8ea1, $5a05df1b, $2d02ef8d
);
{------------------------------------------------------------------------------}
function sslencode(pcname, pccompany, pcapptitle, pcmajor: string): string;
begin
{ encrypt the data using the major version number to seed the encryption routine }
sslcrypt(null_string, strtointdef( pcmajor, 0 ));
sslcrypt(pchar( pcapptitle ));
sslcrypt(pchar( pcname ));
result := sslcrypt( pchar( pccompany ));
end;
{------------------------------------------------------------------------------}
function sslcrypt(pcstring : pchar; pnseed : integer = 0) : string ;
var
nstringlen, ncharcount : integer;
ninterim, nchar : byte;
cchar : char;
begin
nstringlen := length( pcstring );
if nstringlen = 0 then
begin
gnkey := pnseed;
gnsalt := pnseed * 100;
end
else
begin
result := '';
for ncharcount := 0 to nstringlen - 1 do
begin
cchar := pcstring[ ncharcount ];
{ only encipher printable characters }
if (( cchar >= ' ' ) and ( cchar <= '~' )) then
begin
gnkey := ( gnkey and $1fffffff ) xor (( gnkey shr 29 ) and $31 );
nchar := byte( cchar );
ninterim := mod95(( gnkey div 95 ) - ( nchar - 32 )) + 32;
inc( gnsalt );
if ( gnsalt >= 20857 ) then
gnsalt := 0;
gnkey := gnkey + gnkey + ( ninterim xor nchar ) + gnsalt;
result := result + char(ninterim);
end;
end;
end;
end;
{------------------------------------------------------------------------------}
function mod95(pnval : integer): integer;
begin
result := pnval;
while ( result >= 9500 ) do
result := result - 9500;
while ( result >= 950 ) do
result := result - 950;
while ( result >= 95 ) do
result := result - 95;
while ( result < 0 ) do
result := result + 95;
end;
{------------------------------------------------------------------------------}
function sslgeneratekey(pcname, pccompany, pcapplication, pcmajor : string) : string;
var
ckey : string;
begin
ckey := pcname + pccompany + pcapplication + pcmajor + sslencode(pcname, pccompany, pcapplication, pcmajor);
result := crcexecute( ckey );
end;
{------------------------------------------------------------------------------}
function crcexecute(pcstring : string) : string ;
var
nx : integer;
ncrcval : longword;
begin
ncrcval := 0;
for nx := 1 to length( pcstring ) do
ncrcval := crctable[byte(ncrcval xor byte(pcstring[nx]))] xor (( ncrcval shr 8 ) and $00ffffff );
result := lowercase( inttohex( ncrcval, 8 ));
end;
{------------------------------------------------------------------------------}
end.