我对数据库不太明白
　我想问一下
　　假如用户注册了，密码忘记了，我想打开数据库查找那个用户的　密码　
那是在数据库中的密码已经通过ＭＤ５加密了，例如用户名字admin　密码：5fbc1b594d0c65b0
那这个密码怎么变成没有被ＭＤ５加密前的密码呢？

MD5加密的原理：
[CODE]<%
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)
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 md5_f(x, y, z)
md5_f = (x and y) or ((not x) and z)
end function
private function md5_g(x, y, z)
md5_g = (x and z) or (y and (not z))
end function
private function md5_h(x, y, z)
md5_h = (x xor y xor z)
end function
private function md5_i(x, y, z)
md5_i = (y xor (x or (not z)))
end function
private sub md5_ff(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(md5_f(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub md5_gg(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(md5_g(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub md5_hh(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(md5_h(b, c, d), x), ac))
a = rotateleft(a, s)
a = addunsigned(a, b)
end sub
private sub md5_ii(a, b, c, d, x, s, ac)
a = addunsigned(a, addunsigned(addunsigned(md5_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 md5(smessage)
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)
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
md5_ff a, b, c, d, x(k + 0), s11, &hd76aa478
md5_ff d, a, b, c, x(k + 1), s12, &he8c7b756
md5_ff c, d, a, b, x(k + 2), s13, &h242070db
md5_ff b, c, d, a, x(k + 3), s14, &hc1bdceee
md5_ff a, b, c, d, x(k + 4), s11, &hf57c0faf
md5_ff d, a, b, c, x(k + 5), s12, &h4787c62a
md5_ff c, d, a, b, x(k + 6), s13, &ha8304613
md5_ff b, c, d, a, x(k + 7), s14, &hfd469501
md5_ff a, b, c, d, x(k + 8), s11, &h698098d8
md5_ff d, a, b, c, x(k + 9), s12, &h8b44f7af
md5_ff c, d, a, b, x(k + 10), s13, &hffff5bb1
md5_ff b, c, d, a, x(k + 11), s14, &h895cd7be
md5_ff a, b, c, d, x(k + 12), s11, &h6b901122
md5_ff d, a, b, c, x(k + 13), s12, &hfd987193
md5_ff c, d, a, b, x(k + 14), s13, &ha679438e
md5_ff b, c, d, a, x(k + 15), s14, &h49b40821
md5_gg a, b, c, d, x(k + 1), s21, &hf61e2562
md5_gg d, a, b, c, x(k + 6), s22, &hc040b340
md5_gg c, d, a, b, x(k + 11), s23, &h265e5a51
md5_gg b, c, d, a, x(k + 0), s24, &he9b6c7aa
md5_gg a, b, c, d, x(k + 5), s21, &hd62f105d
md5_gg d, a, b, c, x(k + 10), s22, &h2441453
md5_gg c, d, a, b, x(k + 15), s23, &hd8a1e681
md5_gg b, c, d, a, x(k + 4), s24, &he7d3fbc8
md5_gg a, b, c, d, x(k + 9), s21, &h21e1cde6
md5_gg d, a, b, c, x(k + 14), s22, &hc33707d6
md5_gg c, d, a, b, x(k + 3), s23, &hf4d50d87
md5_gg b, c, d, a, x(k + 8), s24, &h455a14ed
md5_gg a, b, c, d, x(k + 13), s21, &ha9e3e905
md5_gg d, a, b, c, x(k + 2), s22, &hfcefa3f8
md5_gg c, d, a, b, x(k + 7), s23, &h676f02d9
md5_gg b, c, d, a, x(k + 12), s24, &h8d2a4c8a
md5_hh a, b, c, d, x(k + 5), s31, &hfffa3942
md5_hh d, a, b, c, x(k + 8), s32, &h8771f681
md5_hh c, d, a, b, x(k + 11), s33, &h6d9d6122
md5_hh b, c, d, a, x(k + 14), s34, &hfde5380c
md5_hh a, b, c, d, x(k + 1), s31, &ha4beea44
md5_hh d, a, b, c, x(k + 4), s32, &h4bdecfa9
md5_hh c, d, a, b, x(k + 7), s33, &hf6bb4b60
md5_hh b, c, d, a, x(k + 10), s34, &hbebfbc70
md5_hh a, b, c, d, x(k + 13), s31, &h289b7ec6
md5_hh d, a, b, c, x(k + 0), s32, &heaa127fa
md5_hh c, d, a, b, x(k + 3), s33, &hd4ef3085
md5_hh b, c, d, a, x(k + 6), s34, &h4881d05
md5_hh a, b, c, d, x(k + 9), s31, &hd9d4d039
md5_hh d, a, b, c, x(k + 12), s32, &he6db99e5
md5_hh c, d, a, b, x(k + 15), s33, &h1fa27cf8
md5_hh b, c, d, a, x(k + 2), s34, &hc4ac5665
md5_ii a, b, c, d, x(k + 0), s41, &hf4292244
md5_ii d, a, b, c, x(k + 7), s42, &h432aff97
md5_ii c, d, a, b, x(k + 14), s43, &hab9423a7
md5_ii b, c, d, a, x(k + 5), s44, &hfc93a039
md5_ii a, b, c, d, x(k + 12), s41, &h655b59c3
md5_ii d, a, b, c, x(k + 3), s42, &h8f0ccc92
md5_ii c, d, a, b, x(k + 10), s43, &hffeff47d
md5_ii b, c, d, a, x(k + 1), s44, &h85845dd1
md5_ii a, b, c, d, x(k + 8), s41, &h6fa87e4f
md5_ii d, a, b, c, x(k + 15), s42, &hfe2ce6e0
md5_ii c, d, a, b, x(k + 6), s43, &ha3014314
md5_ii b, c, d, a, x(k + 13), s44, &h4e0811a1
md5_ii a, b, c, d, x(k + 4), s41, &hf7537e82
md5_ii d, a, b, c, x(k + 11), s42, &hbd3af235
md5_ii c, d, a, b, x(k + 2), s43, &h2ad7d2bb
md5_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
md5 = lcase(wordtohex(a) & wordtohex(b) & wordtohex(c) & wordtohex(d))
'md5=lcase(wordtohex(b) & wordtohex(c)) 'i crop this to fit 16byte database password :d
md5=ucase(md5)
end function

public function md5_16(smessage)
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)
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
md5_ff a, b, c, d, x(k + 0), s11, &hd76aa478
md5_ff d, a, b, c, x(k + 1), s12, &he8c7b756
md5_ff c, d, a, b, x(k + 2), s13, &h242070db
md5_ff b, c, d, a, x(k + 3), s14, &hc1bdceee
md5_ff a, b, c, d, x(k + 4), s11, &hf57c0faf
md5_ff d, a, b, c, x(k + 5), s12, &h4787c62a
md5_ff c, d, a, b, x(k + 6), s13, &ha8304613
md5_ff b, c, d, a, x(k + 7), s14, &hfd469501
md5_ff a, b, c, d, x(k + 8), s11, &h698098d8
md5_ff d, a, b, c, x(k + 9), s12, &h8b44f7af
md5_ff c, d, a, b, x(k + 10), s13, &hffff5bb1
md5_ff b, c, d, a, x(k + 11), s14, &h895cd7be
md5_ff a, b, c, d, x(k + 12), s11, &h6b901122
md5_ff d, a, b, c, x(k + 13), s12, &hfd987193
md5_ff c, d, a, b, x(k + 14), s13, &ha679438e
md5_ff b, c, d, a, x(k + 15), s14, &h49b40821
md5_gg a, b, c, d, x(k + 1), s21, &hf61e2562
md5_gg d, a, b, c, x(k + 6), s22, &hc040b340
md5_gg c, d, a, b, x(k + 11), s23, &h265e5a51
md5_gg b, c, d, a, x(k + 0), s24, &he9b6c7aa
md5_gg a, b, c, d, x(k + 5), s21, &hd62f105d
md5_gg d, a, b, c, x(k + 10), s22, &h2441453
md5_gg c, d, a, b, x(k + 15), s23, &hd8a1e681
md5_gg b, c, d, a, x(k + 4), s24, &he7d3fbc8
md5_gg a, b, c, d, x(k + 9), s21, &h21e1cde6
md5_gg d, a, b, c, x(k + 14), s22, &hc33707d6
md5_gg c, d, a, b, x(k + 3), s23, &hf4d50d87
md5_gg b, c, d, a, x(k + 8), s24, &h455a14ed
md5_gg a, b, c, d, x(k + 13), s21, &ha9e3e905
md5_gg d, a, b, c, x(k + 2), s22, &hfcefa3f8
md5_gg c, d, a, b, x(k + 7), s23, &h676f02d9
md5_gg b, c, d, a, x(k + 12), s24, &h8d2a4c8a
md5_hh a, b, c, d, x(k + 5), s31, &hfffa3942
md5_hh d, a, b, c, x(k + 8), s32, &h8771f681
md5_hh c, d, a, b, x(k + 11), s33, &h6d9d6122
md5_hh b, c, d, a, x(k + 14), s34, &hfde5380c
md5_hh a, b, c, d, x(k + 1), s31, &ha4beea44
md5_hh d, a, b, c, x(k + 4), s32, &h4bdecfa9
md5_hh c, d, a, b, x(k + 7), s33, &hf6bb4b60
md5_hh b, c, d, a, x(k + 10), s34, &hbebfbc70
md5_hh a, b, c, d, x(k + 13), s31, &h289b7ec6
md5_hh d, a, b, c, x(k + 0), s32, &heaa127fa
md5_hh c, d, a, b, x(k + 3), s33, &hd4ef3085
md5_hh b, c, d, a, x(k + 6), s34, &h4881d05
md5_hh a, b, c, d, x(k + 9), s31, &hd9d4d039
md5_hh d, a, b, c, x(k + 12), s32, &he6db99e5
md5_hh c, d, a, b, x(k + 15), s33, &h1fa27cf8
md5_hh b, c, d, a, x(k + 2), s34, &hc4ac5665
md5_ii a, b, c, d, x(k + 0), s41, &hf4292244
md5_ii d, a, b, c, x(k + 7), s42, &h432aff97
md5_ii c, d, a, b, x(k + 14), s43, &hab9423a7
md5_ii b, c, d, a, x(k + 5), s44, &hfc93a039
md5_ii a, b, c, d, x(k + 12), s41, &h655b59c3
md5_ii d, a, b, c, x(k + 3), s42, &h8f0ccc92
md5_ii c, d, a, b, x(k + 10), s43, &hffeff47d
md5_ii b, c, d, a, x(k + 1), s44, &h85845dd1
md5_ii a, b, c, d, x(k + 8), s41, &h6fa87e4f
md5_ii d, a, b, c, x(k + 15), s42, &hfe2ce6e0
md5_ii c, d, a, b, x(k + 6), s43, &ha3014314
md5_ii b, c, d, a, x(k + 13), s44, &h4e0811a1
md5_ii a, b, c, d, x(k + 4), s41, &hf7537e82
md5_ii d, a, b, c, x(k + 11), s42, &hbd3af235
md5_ii c, d, a, b, x(k + 2), s43, &h2ad7d2bb
md5_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
'md5 = lcase(wordtohex(a) & wordtohex(b) & wordtohex(c) & wordtohex(d))
md5_16=lcase(wordtohex(b) & wordtohex(c)) 'i crop this to fit 16byte database password :d
md5_16=ucase(md5_16)
end function
%>
调用使用下面的方法
<%
password="123456"
response.write MD5(password)
%> [/CODE]
所以“123456”md5加密后就是下面的一段代码：

E10ADC3949BA59ABBE56E057F20F883E

所以你只要把数据库里面的密码字段的内容用上面的一串代码代替，明文密码就改成了“123456”了 ，你就可以用123456登入了，然后再修改你想要改成的密码。

[此贴子已经被作者于2007-6-23 12:26:09编辑过]

[此贴子已经被作者于2007-6-23 12:32:09编辑过]