Module: S3SwfUpload::Signature

Defined in:
lib/tenon/s3_signature.rb

Instance Method Summary collapse

Instance Method Details

#assert(expr) ⇒ Object

Absolute barebones “unit” tests



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# File 'lib/tenon/s3_signature.rb', line 16

def assert(expr)
  fail 'Assertion failed' unless expr
end

#b64_hmac_sha1(key, data) ⇒ Object 



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# File 'lib/tenon/s3_signature.rb', line 11

def b64_hmac_sha1(key, data)
  binb2b64(core_hmac_sha1(key, data))
end

#binb2b64(binarray) ⇒ Object

Convert an array of big-endian words to a base-64 string



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# File 'lib/tenon/s3_signature.rb', line 183

def binb2b64(binarray)
  tab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  str = ''

  # for(var i = 0; i < binarray.length * 4; i += 3)
  i = 0
  while i < binarray.length * 4
    triplet = (((binarray[i >> 2].to_i >> 8 * (3 - i % 4)) & 0xFF) << 16) |
                 (((binarray[i + 1 >> 2].to_i >> 8 * (3 - (i + 1) % 4)) & 0xFF) << 8) |
                  ((binarray[i + 2 >> 2].to_i >> 8 * (3 - (i + 2) % 4)) & 0xFF)
    # for(var j = 0; j < 4; j++)
    j = 0
    while j < 4
      if i * 8 + j * 6 > binarray.length * 32
        str += $b64pad
      else
        str += tab[(triplet >> 6 * (3 - j)) & 0x3F].chr
      end
      j += 1
    end
    i += 3
  end
  str
end

#binb2hex(binarray) ⇒ Object

Convert an array of big-endian words to a hex string.



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# File 'lib/tenon/s3_signature.rb', line 169

def binb2hex(binarray)
  hex_tab = $hexcase ? '0123456789ABCDEF' : '0123456789abcdef'
  str = ''
  # for(var i = 0; i < binarray.length * 4; i++)
  i = 0
  while i < binarray.length * 4
    str += hex_tab[(binarray[i >> 2] >> ((3 - i % 4) * 8 + 4)) & 0xF].chr +
           hex_tab[(binarray[i >> 2] >> ((3 - i % 4) * 8)) & 0xF].chr
    i += 1
  end
  str
end

#core_hmac_sha1(key, data) ⇒ Object

Calculate the HMAC-SHA1 of a key and some data



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# File 'lib/tenon/s3_signature.rb', line 111

def core_hmac_sha1(key, data)
  bkey = str2binb(key)
  bkey = core_sha1(bkey, key.length * $chrsz) if bkey.length > 16

  ipad = Array.new(16, 0)
  opad = Array.new(16, 0)
  # for(var i = 0; i < 16; i++)
  i = 0
  while i < 16
    ipad[i] = (bkey[i] || 0) ^ 0x36363636
    opad[i] = (bkey[i] || 0) ^ 0x5C5C5C5C
    i += 1
  end

  hash = core_sha1((ipad + str2binb(data)), 512 + data.length * $chrsz)
  core_sha1((opad + hash), 512 + 160)
end

#core_sha1(x, len) ⇒ Object

Calculate the SHA-1 of an array of big-endian words, and a bit length



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# File 'lib/tenon/s3_signature.rb', line 37

def core_sha1(x, len)
  # append padding
  x[len >> 5] ||= 0
  x[len >> 5] |= 0x80 << (24 - len % 32)
  x[((len + 64 >> 9) << 4) + 15] = len

  w = Array.new(80, 0)
  a =  1_732_584_193
  b = -271_733_879
  c = -1_732_584_194
  d =  271_733_878
  e = -1_009_589_776

  # for(var i = 0; i < x.length; i += 16)
  i = 0
  while i < x.length
    olda = a
    oldb = b
    oldc = c
    oldd = d
    olde = e

    # for(var j = 0; j < 80; j++)
    j = 0
    while j < 80
      if j < 16
        w[j] = x[i + j] || 0
      else
        w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1)
      end

      t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
                   safe_add(safe_add(e, w[j]), sha1_kt(j)))
      e = d
      d = c
      c = rol(b, 30)
      b = a
      a = t
      j += 1
    end

    a = safe_add(a, olda)
    b = safe_add(b, oldb)
    c = safe_add(c, oldc)
    d = safe_add(d, oldd)
    e = safe_add(e, olde)
    i += 16
  end
  [a, b, c, d, e]
end

#hex_sha1(s) ⇒ Object 



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# File 'lib/tenon/s3_signature.rb', line 7

def hex_sha1(s)
  binb2hex(core_sha1(str2binb(s), s.length * $chrsz))
end

#rol(num, cnt) ⇒ Object

Bitwise rotate a 32-bit number to the left.



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# File 'lib/tenon/s3_signature.rb', line 137

def rol(num, cnt)
  # return (num << cnt) | (num >>> (32 - cnt))
  (num.js_shl(cnt)) | (num.js_shr_zf(32 - cnt))
end

#safe_add(x, y) ⇒ Object

Add integers, wrapping at 2^32. This uses 16-bit operations internally to work around bugs in some JS interpreters.



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# File 'lib/tenon/s3_signature.rb', line 131

def safe_add(x, y)
  v = (x + y) % (2**32)
  v > 2**31 ? v - 2**32 : v
end

#self_test ⇒ Object 



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# File 'lib/tenon/s3_signature.rb', line 20

def self_test
  num, cnt = [1_732_584_193, 5]

  assert(core_sha1(str2binb('abc'), 'abc'.length) == [-519_653_305, -1_566_383_753, -2_070_791_546, -753_729_183, -204_968_198])
  assert(rol(num, cnt) == -391_880_660)
  assert(safe_add(2_042_729_798, num) == -519_653_305)
  assert((num.js_shl(cnt)) == -391_880_672)
  assert((num.js_shr_zf(32 - cnt)) == 12)
  assert(sha1_ft(0, -271_733_879, -1_732_584_194, 271_733_878) == -1_732_584_194)
  assert(sha1_kt(0) == 1_518_500_249)
  assert(safe_add(safe_add(rol(num, cnt), sha1_ft(0, -271_733_879, -1_732_584_194, 271_733_878)), safe_add(safe_add(-1_009_589_776, 1_902_273_280), sha1_kt(0))) == 286_718_899)
  assert(str2binb('foo bar hey there') == [1_718_578_976, 1_650_553_376, 1_751_480_608, 1_952_998_770, 1_694_498_816])
  assert(hex_sha1('abc') == 'a9993e364706816aba3e25717850c26c9cd0d89d')
  assert(b64_hmac_sha1('foo', 'abc') == 'frFXMR9cNoJdsSPnjebZpBhUKzI=')
end

#sha1_ft(t, b, c, d) ⇒ Object

Perform the appropriate triplet combination function for the current iteration



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# File 'lib/tenon/s3_signature.rb', line 90

def sha1_ft(t, b, c, d)
  return (b & c) | ((~b) & d) if t < 20
  return b ^ c ^ d if t < 40
  return (b & c) | (b & d) | (c & d) if t < 60
  b ^ c ^ d
end

#sha1_kt(t) ⇒ Object

Determine the appropriate additive constant for the current iteration



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# File 'lib/tenon/s3_signature.rb', line 98

def sha1_kt(t)
  if t < 20
    1_518_500_249
  elsif t < 40
    1_859_775_393
  elsif t < 60
    -1_894_007_588
  else
    -899_497_514
  end
end

#str2binb(str) ⇒ Object

Convert an 8-bit or 16-bit string to an array of big-endian words In 8-bit function, characters >255 have their hi-byte silently ignored.



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# File 'lib/tenon/s3_signature.rb', line 144

def str2binb(str)
  bin = []
  mask = (1 << $chrsz) - 1
  # for(var i = 0; i < str.length * $chrsz; i += $chrsz)
  i = 0
  while i < str.length * $chrsz
    bin[i >> 5] ||= 0
    bin[i >> 5] |= (str[i / $chrsz] & mask) << (32 - $chrsz - i % 32)
    i += $chrsz
  end
  bin
end