在.net中,由于.net framework 封装了常见的加密算法,因此实现标准的md5算法只需要短短几行代码即可实现:
public string md5(string strpassword)
{
md5cryptoserviceprovider hashmd5;
hashmd5 = new md5cryptoserviceprovider();
return bitconverter.tostring(hashmd5.computehash(encoding.default.getbytes(strpassword))).replace("-","").tolower();
}
,但是当加密字符串含有中文或者其它双字节字符时,这种算法的结果与目前网上流行的asp写的md5算法的结果却不一致,这主要是由于目前网上流行的asp写的md5加密算法,存在一个缺陷,它使用了mid函数，取出的是“字符”，而正确的做法应该是取出字节,因此当加密字符串有双字节字符时,结果会与标准的md5算法不一致.。但是由于在asp向asp.net的系统进行升级的过程中，已经向数据库内写入了大量以前asp算法加密的密码，为了使新系统能够与原来的系统完全兼容，因此只有在.net 环境下实现与原来asp算法完全一致的md5算法。我的实现思路如下：
1、先用正则表达式对要加密的字符串进行判断，是否含有双字节字符。
2、如果含有双字节字符，调用实现与asp算法一致的非托管com组件进行处理。（这个组件只需要将原asp加密算法代码进行适当修改，然后加入vb6中进行编译即可得到）。
3、否则直接调用.net的标准md5加密算法。
可能有的朋友会问到，为什么不都直接调用com组件来加密呢？这主要是从性能角度考虑的，由于调用非托管com组件，.net需要生成一个代理类与之交互，所以在性能方面要远远低于.net内置的函数。
下面给出所有代码：
原asp加密代码：
<%
private const bits_to_a_byte = 8
private const bytes_to_a_word = 4
private const bits_to_a_word = 32
private m_lonbits(30)
private m_l2power(30)
m_lonbits(0) = clng(1)
m_lonbits(1) = clng(3)
m_lonbits(2) = clng(7)
m_lonbits(3) = clng(15)
m_lonbits(4) = clng(31)
m_lonbits(5) = clng(63)
m_lonbits(6) = clng(127)
m_lonbits(7) = clng(255)
m_lonbits(8) = clng(511)
m_lonbits(9) = clng(1023)
m_lonbits(10) = clng(2047)
m_lonbits(11) = clng(4095)
m_lonbits(12) = clng(8191)
m_lonbits(13) = clng(16383)
m_lonbits(14) = clng(32767)
m_lonbits(15) = clng(65535)
m_lonbits(16) = clng(131071)
m_lonbits(17) = clng(262143)
m_lonbits(18) = clng(524287)
m_lonbits(19) = clng(1048575)
m_lonbits(20) = clng(2097151)
m_lonbits(21) = clng(4194303)
m_lonbits(22) = clng(8388607)
m_lonbits(23) = clng(16777215)
m_lonbits(24) = clng(33554431)
m_lonbits(25) = clng(67108863)
m_lonbits(26) = clng(134217727)
m_lonbits(27) = clng(268435455)
m_lonbits(28) = clng(536870911)
m_lonbits(29) = clng(1073741823)
m_lonbits(30) = clng(2147483647)
m_l2power(0) = clng(1)
m_l2power(1) = clng(2)
m_l2power(2) = clng(4)
m_l2power(3) = clng(8)
m_l2power(4) = clng(16)
m_l2power(5) = clng(32)
m_l2power(6) = clng(64)
m_l2power(7) = clng(128)
m_l2power(8) = clng(256)
m_l2power(9) = clng(512)
m_l2power(10) = clng(1024)
m_l2power(11) = clng(2048)
m_l2power(12) = clng(4096)
m_l2power(13) = clng(8192)
m_l2power(14) = clng(16384)
m_l2power(15) = clng(32768)
m_l2power(16) = clng(65536)
m_l2power(17) = clng(131072)
m_l2power(18) = clng(262144)
m_l2power(19) = clng(524288)
m_l2power(20) = clng(1048576)
m_l2power(21) = clng(2097152)
m_l2power(22) = clng(4194304)
m_l2power(23) = clng(8388608)
m_l2power(24) = clng(16777216)
m_l2power(25) = clng(33554432)
m_l2power(26) = clng(67108864)
m_l2power(27) = clng(134217728)
m_l2power(28) = clng(268435456)
m_l2power(29) = clng(536870912)
m_l2power(30) = clng(1073741824)
private function lshift(lvalue, ishiftbits)
if ishiftbits = 0 then
lshift = lvalue
exit function
elseif ishiftbits = 31 then
if lvalue and 1 then
lshift = &h80000000
else
lshift = 0
end if
exit function
elseif ishiftbits < 0 or ishiftbits > 31 then
err.raise 6
end if
if (lvalue and m_l2power(31 - ishiftbits)) then
lshift = ((lvalue and m_lonbits(31 - (ishiftbits + 1))) * m_l2power(ishiftbits)) or &h80000000
else
lshift = ((lvalue and m_lonbits(31 - ishiftbits)) * m_l2power(ishiftbits))
end if
end function
private function rshift(lvalue, ishiftbits)
if ishiftbits = 0 then
rshift = lvalue
exit function
elseif ishiftbits = 31 then
if lvalue and &h80000000 then
rshift = 1
else
rshift = 0
end if
exit function
elseif ishiftbits < 0 or ishiftbits > 31 then
err.raise 6
end if
rshift = (lvalue and &h7ffffffe) / m_l2power(ishiftbits)
if (lvalue and &h80000000) then
rshift = (rshift or (&h40000000 / m_l2power(ishiftbits - 1)))
end if
end function
private function rotateleft(lvalue, ishiftbits)
rotateleft = lshift(lvalue, ishiftbits) or rshift(lvalue, (32 - ishiftbits))
end function
private function addunsigned(lx, ly)
dim lx4
dim ly4
dim lx8
dim ly8
dim lresult
lx8 = lx and &h80000000
ly8 = ly and &h80000000
lx4 = lx and &h40000000
ly4 = ly and &h40000000
lresult = (lx and &h3fffffff) + (ly and &h3fffffff)
if lx4 and ly4 then
lresult = lresult xor &h80000000 xor lx8 xor ly8
elseif lx4 or ly4 then
if lresult and &h40000000 then
lresult = lresult xor &hc0000000 xor lx8 xor ly8
else
lresult = lresult xor &h40000000 xor lx8 xor ly8
end if
else
lresult = lresult xor lx8 xor ly8
end if
addunsigned = lresult
end function
private function f(x, y, z)
f = (x and y) or ((not x) and z)
end function
private function g(x, y, z)
g = (x and z) or (y and (not z))
end function
private function h(x, y, z)
h = (x xor y xor z)
end function
private function i(x, y, z)
i = (y xor (x or (not z)))
end function
private sub ff(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(f(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub gg(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(g(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub hh(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(h(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub ii(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(i(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private function converttowordarray(smessage)
dim lmessagelength
dim lnumberofwords
dim lwordarray()
dim lbyteposition
dim lbytecount
dim lwordcount
const modulus_bits = 512
const congruent_bits = 448
lmessagelength = len(smessage)
lnumberofwords = (((lmessagelength + ((modulus_bits - congruent_bits) / bits_to_a_byte)) / (modulus_bits / bits_to_a_byte)) + 1) * (modulus_bits / bits_to_a_word)
redim lwordarray(lnumberofwords - 1)
lbyteposition = 0
lbytecount = 0
do until lbytecount >= lmessagelength
lwordcount = lbytecount / bytes_to_a_word
lbyteposition = (lbytecount mod bytes_to_a_word) * bits_to_a_byte
lwordarray(lwordcount) = lwordarray(lwordcount) or lshift(asc(mid(smessage, lbytecount + 1, 1)), lbyteposition)
lbytecount = lbytecount + 1
loop
lwordcount = lbytecount / bytes_to_a_word
lbyteposition = (lbytecount mod bytes_to_a_word) * bits_to_a_byte
lwordarray(lwordcount) = lwordarray(lwordcount) or lshift(&h80, lbyteposition)
lwordarray(lnumberofwords - 2) = lshift(lmessagelength, 3)
lwordarray(lnumberofwords - 1) = rshift(lmessagelength, 29)
converttowordarray = lwordarray
end function
private function wordtohex(lvalue)
dim lbyte
dim lcount
for lcount = 0 to 3
lbyte = rshift(lvalue, lcount * bits_to_a_byte) and m_lonbits(bits_to_a_byte - 1)
wordtohex = wordtohex & right("0" & hex(lbyte), 2)
next
end function
public function calcmd5(smessage)
dim x
dim k
dim aa
dim bb
dim cc
dim dd
dim a
dim b
dim c
dim d
const s11 = 7
const s12 = 12
const s13 = 17
const s14 = 22
const s21 = 5
const s22 = 9
const s23 = 14
const s24 = 20
const s31 = 4
const s32 = 11
const s33 = 16
const s34 = 23
const s41 = 6
const s42 = 10
const s43 = 15
const s44 = 21
x = converttowordarray(smessage)
a = &h67452301
b = &hefcdab89
c = &h98badcfe
d = &h10325476
for k = 0 to ubound(x) step 16
aa = a
bb = b
cc = c
dd = d
ff a, b, c, d, x(k + 0), s11, &hd76aa478
ff d, a, b, c, x(k + 1), s12, &he8c7b756
ff c, d, a, b, x(k + 2), s13, &h242070db
ff b, c, d, a, x(k + 3), s14, &hc1bdceee
ff a, b, c, d, x(k + 4), s11, &hf57c0faf
ff d, a, b, c, x(k + 5), s12, &h4787c62a
ff c, d, a, b, x(k + 6), s13, &ha8304613
ff b, c, d, a, x(k + 7), s14, &hfd469501
ff a, b, c, d, x(k + 8), s11, &h698098d8
ff d, a, b, c, x(k + 9), s12, &h8b44f7af
ff c, d, a, b, x(k + 10), s13, &hffff5bb1
ff b, c, d, a, x(k + 11), s14, &h895cd7be
ff a, b, c, d, x(k + 12), s11, &h6b901122
ff d, a, b, c, x(k + 13), s12, &hfd987193
ff c, d, a, b, x(k + 14), s13, &ha679438e
ff b, c, d, a, x(k + 15), s14, &h49b40821
gg a, b, c, d, x(k + 1), s21, &hf61e2562
gg d, a, b, c, x(k + 6), s22, &hc040b340
gg c, d, a, b, x(k + 11), s23, &h265e5a51
gg b, c, d, a, x(k + 0), s24, &he9b6c7aa
gg a, b, c, d, x(k + 5), s21, &hd62f105d
gg d, a, b, c, x(k + 10), s22, &h2441453
gg c, d, a, b, x(k + 15), s23, &hd8a1e681
gg b, c, d, a, x(k + 4), s24, &he7d3fbc8
gg a, b, c, d, x(k + 9), s21, &h21e1cde6
gg d, a, b, c, x(k + 14), s22, &hc33707d6
gg c, d, a, b, x(k + 3), s23, &hf4d50d87
gg b, c, d, a, x(k + 8), s24, &h455a14ed
gg a, b, c, d, x(k + 13), s21, &ha9e3e905
gg d, a, b, c, x(k + 2), s22, &hfcefa3f8
gg c, d, a, b, x(k + 7), s23, &h676f02d9
gg b, c, d, a, x(k + 12), s24, &h8d2a4c8a
hh a, b, c, d, x(k + 5), s31, &hfffa3942
hh d, a, b, c, x(k + 8), s32, &h8771f681
hh c, d, a, b, x(k + 11), s33, &h6d9d6122
hh b, c, d, a, x(k + 14), s34, &hfde5380c
hh a, b, c, d, x(k + 1), s31, &ha4beea44
hh d, a, b, c, x(k + 4), s32, &h4bdecfa9
hh c, d, a, b, x(k + 7), s33, &hf6bb4b60
hh b, c, d, a, x(k + 10), s34, &hbebfbc70
hh a, b, c, d, x(k + 13), s31, &h289b7ec6
hh d, a, b, c, x(k + 0), s32, &heaa127fa
hh c, d, a, b, x(k + 3), s33, &hd4ef3085
hh b, c, d, a, x(k + 6), s34, &h4881d05
hh a, b, c, d, x(k + 9), s31, &hd9d4d039
hh d, a, b, c, x(k + 12), s32, &he6db99e5
hh c, d, a, b, x(k + 15), s33, &h1fa27cf8
hh b, c, d, a, x(k + 2), s34, &hc4ac5665
ii a, b, c, d, x(k + 0), s41, &hf4292244
ii d, a, b, c, x(k + 7), s42, &h432aff97
ii c, d, a, b, x(k + 14), s43, &hab9423a7
ii b, c, d, a, x(k + 5), s44, &hfc93a039
ii a, b, c, d, x(k + 12), s41, &h655b59c3
ii d, a, b, c, x(k + 3), s42, &h8f0ccc92
ii c, d, a, b, x(k + 10), s43, &hffeff47d
ii b, c, d, a, x(k + 1), s44, &h85845dd1
ii a, b, c, d, x(k + 8), s41, &h6fa87e4f
ii d, a, b, c, x(k + 15), s42, &hfe2ce6e0
ii c, d, a, b, x(k + 6), s43, &ha3014314
ii b, c, d, a, x(k + 13), s44, &h4e0811a1
ii a, b, c, d, x(k + 4), s41, &hf7537e82
ii d, a, b, c, x(k + 11), s42, &hbd3af235
ii c, d, a, b, x(k + 2), s43, &h2ad7d2bb
ii b, c, d, a, x(k + 9), s44, &heb86d391
a = addunsigned(a, aa)
b = addunsigned(b, bb)
c = addunsigned(c, cc)
d = addunsigned(d, dd)
next
calcmd5 = lcase(wordtohex(a) & wordtohex(b) & wordtohex(c) & wordtohex(d))
end function
%>
这段代码，只需要复制到vb activex dll项目中，将变量初始化的代码移到类初始化的位置编译即可生成同样算法的非托管com组件。
在.net中，引用com组件，并使用如下方法进行调用：
using system;
using system.text;
using system.text.regularexpressions;
using system.security.cryptography;
using md5;
namespace yournamespace
{
public class aspmd5
{
/// <summary>
/// 与asp兼容的md5加密算法
/// </summary>
/// <param name="strpassword"></param>
/// <returns></returns>
public string md5(string strpassword)
{
system.text.regularexpressions.regex regexp = new regex(@"[^x00-xff]"); //匹配汉字
if(regexp.ismatch(strpassword))
{
//引用com组件,实现与asp兼容的md5算法
md5.securitymd5class obj = new securitymd5class(); //注意：在vb类模块里，这里的类名为securitymd5class
return obj. calcmd5(strpassword).tolower();
}
else
{
//标准md5算法
md5cryptoserviceprovider hashmd5;
hashmd5 = new md5cryptoserviceprovider();
return bitconverter.tostring(hashmd5.computehash(encoding.default.getbytes(strpassword))).replace("-","").tolower();
}
}
}
}
由于时间仓促，可能文章中有写得不够准确的地方，欢迎批评指正，同时如果其它朋友有更好的实现方法，欢迎来信交流。
由于时间仓促，可能文章中有写得不够准确的地方，欢迎批评指正，同时如果其它朋友有更好的实现方法，欢迎来信交流。新闻热点
疑难解答
