MD5加密算法 ASP版

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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(