Fonction SHA1 en ASP

Le SHA1 : http://www.itl.nist.gov/fipspubs/fip180-1.htm

Original : http://p2p.wrox.com/archive/proasp_howto/2002-02/27.asp

<%
function tohex(value)
  value = clng(value)
  tohex = lcase(hex(value))
  do while len(tohex) < 8
    tohex = "0" & tohex
  loop
end function
 
function tobin(value)
  dim hexstr
  hexstr = tohex(value)
  tobin = ""
  for i = 1 to len(hexstr)
    select case mid(hexstr, i, 1)
      case "f", "F"
        tobin = tobin & "1111"
      case "e", "E"
        tobin = tobin & "1110"
      case "d", "D"
        tobin = tobin & "1101"
      case "c", "C"
        tobin = tobin & "1100"
      case "b", "B"
        tobin = tobin & "1011"
      case "a", "A"
        tobin = tobin & "1010"
      case "9"
        tobin = tobin & "1001"
      case "8"
        tobin = tobin & "1000"
      case "7"
        tobin = tobin & "0111"
      case "6"
        tobin = tobin & "0110"
      case "5"
        tobin = tobin & "0101"
      case "4"
        tobin = tobin & "0100"
      case "3"
        tobin = tobin & "0011"
      case "2"
        tobin = tobin & "0010"
      case "1"
        tobin = tobin & "0001"
      case else
        tobin = tobin & "0000"
    end select
  next
end function
 
function bin2dec(binstr)
  dim flip
  flip = false
  bin2dec = clng(0)
  if left(binstr,1) = "0" then
    for i = 1 to len(binstr)
      if mid(binstr,33-i,1)="1" then
        bin2dec = bin2dec + (2^(i-1))
      end if
    next
  else
    for i = 1 to len(binstr)
      if flip then
        if mid(binstr,33-i,1)="0" then
          bin2dec = bin2dec - (2^(i-1))
        end if
      else
        if mid(binstr,33-i,1)="1" then
          bin2dec = bin2dec - (2^(i-1))
          flip = true
        end if
      end if
    next
  end if
end function  
  
function rshift(value,count)
  dim binstr
  if count >= 32 then
    binstr = ""
  elseif count > 0 then
    binstr = left(tobin(value), 32-count)
  else
    binstr = tobin(value)
  end if
  do while len(binstr) < 32
    binstr = "0" + binstr
  loop
  rshift = bin2dec(binstr)  
end function
 
function lshift(value,count)
  dim binstr
  if count >= 32 then
    binstr = ""
  elseif count > 0 then
    binstr = right(tobin(value), 32-count)
  else
    binstr = tobin(value)
  end if
  do while len(binstr) < 32
    binstr = binstr + "0"
  loop
  lshift = bin2dec(binstr)
end function
 
function rol(value,count)
  rol = lshift(value,count) or rshift(value,32-count)
end function
 
function add32(a, b)
  dim bina, binb, total, result, carry
  bina = tobin(a)
  binb = tobin(b)
  result = ""
  carry = "0"
  for i = 1 to 32
    total = 0
    if mid(bina,33-i,1)="1" then total = total + 1
    if mid(binb,33-i,1)="1" then total = total + 1
    if carry="1" then total = total + 1
    select case total
      case 3
        carry = "1"
        result = "1" + result
      case 2
        carry = "1"
        result = "0" + result
      case 1
        carry = "0"
        result = "1" + result
      case else
        carry = "0"
        result = "0" + result
    end select
  next
  add32 = bin2dec(result)    
end function
 
function f(b,c,d,t)
  if t < 20 then
    f = (b and c) or ((not b) and d)
  elseif t < 40 then
    f = b xor c xor d
  elseif t < 60 then
    f = (b and c) or (b and d) or (c and d)
  else
    f = b xor c xor d
  end if
end function
 
function k(t)
  if t < 20 then
    k = clng(1518500249)
  elseif t < 40 then
    k = clng(1859775393)
  elseif t < 60 then
    k = clng(-1894007588)
  else
    k = clng(-899497514)
  end if
end function
 
function pad(message)
  dim l, n
  l = len(message)
  n = (((l+8) \ 64) + 1)*16
  redim m(n-1)
  for i = 0 to n-1
    m(i) = clng(0)
  next
  for i = 0 to l-1
    m(i\4) = m(i\4) or lshift(asc(mid(message,i+1,1)),(24-(i mod 4)*8))
  next
  m(l\4) = m(l\4) or lshift(clng(128),(24-(l mod 4)*8))
  m(n-1) = l*8
  pad = m
end function
 
function sha1(message)
  dim h0, h1, h2, h3, h4
  dim a, b, c, d, e, temp
  dim l, n
  dim w(79)
  
  l = len(message)
  n = (((l+8) \ 64) + 1)*16
  m = pad(message)
  
  h0 = clng(1732584193)
  h1 = clng(-271733879)
  h2 = clng(-1732584194)
  h3 = clng(271733878)
  h4 = clng(-1009589776)
  
  for block = 0 to n-1 step 16
    a = h0
    b = h1
    c = h2
    d = h3
    e = h4
    for t = 0 to 79
      if t < 16 then
        w(t) = m(block + t)
      else
        w(t) = rol(w(t-3) xor w(t-8) xor w(t-14) xor w(t-16),1)
      end if
      temp = add32(rol(a,5),add32(f(b,c,d,t),add32(e,add32(w(t),k(t)))))
      e = d
      d = c
      c = rol(b,30)
      b = a
      a = temp
    next
    h0 = add32(h0, a)
    h1 = add32(h1, b)
    h2 = add32(h2, c)
    h3 = add32(h3, d)
    h4 = add32(h4, e)
  next
  sha1 = tohex(h0)+tohex(h1)+tohex(h2)+tohex(h3)+tohex(h4)
end function
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