Module: BitcoinCigs

Extended by:
MathHelper
Defined in:
lib/bitcoin_cigs.rb,
lib/bitcoin_cigs/error.rb,
lib/bitcoin_cigs/point.rb,
lib/bitcoin_cigs/base_58.rb,
lib/bitcoin_cigs/version.rb,
lib/bitcoin_cigs/curve_fp.rb,
lib/bitcoin_cigs/public_key.rb,
lib/bitcoin_cigs/math_helper.rb

Defined Under Namespace

Modules: MathHelper Classes: Base58, CurveFp, Error, Point, PublicKey

Constant Summary collapse

P = 
0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F
R = 
0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141
B = 
0x0000000000000000000000000000000000000000000000000000000000000007
A = 
0x0000000000000000000000000000000000000000000000000000000000000000
Gx = 
0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798
Gy = 
0x483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8
CURVE_SECP256K1 = 
::BitcoinCigs::CurveFp.new(P, A, B)
GENERATOR_SECP256K1 = 
::BitcoinCigs::Point.new(CURVE_SECP256K1, Gx, Gy, R)
VERSION = 
"0.0.1"

Class Method Summary collapse

Methods included from MathHelper

inverse_mod, leftmost_bit, ripemd160, sha256, sqrt_mod, str_to_num

Class Method Details

.verify_message(address, signature, message) ⇒ Object 



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# File 'lib/bitcoin_cigs.rb', line 24

def verify_message(address, signature, message)
  begin
    verify_message!(address, signature, message)
    true
  rescue ::BitcoinCigs::Error
    false
  end
end

.verify_message!(address, signature, message) ⇒ Object

Raises:



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# File 'lib/bitcoin_cigs.rb', line 33

def verify_message!(address, signature, message)
  network_version = str_to_num(::BitcoinCigs::Base58.decode(address)) >> (8 * 24)

  message = calculate_hash(format_message_to_sign(message))

  curve = CURVE_SECP256K1
  g = GENERATOR_SECP256K1
  a, b, p = curve.a, curve.b, curve.p
  
  order = g.order
  
  sig = Base64.decode64(signature)
  raise ::BitcoinCigs::Error.new("Bad signature") if sig.size != 65
  
  hb = sig[0].ord
  r, s = [sig[1...33], sig[33...65]].collect { |s| str_to_num(s) }
  
  
  raise ::BitcoinCigs::Error.new("Bad first byte") if hb < 27 || hb >= 35
  
  compressed = false
  if hb >= 31
    compressed = true
    hb -= 4
  end
  
  recid = hb - 27
  x = (r + (recid / 2) * order) % p
  y2 = ((x ** 3 % p) + a * x + b) % p
  yomy = sqrt_mod(y2, p)
  if (yomy - recid) % 2 == 0
    y = yomy
  else
    y = p - yomy
  end
  
  r_point = ::BitcoinCigs::Point.new(curve, x, y, order)
  e = str_to_num(message)
  minus_e = -e % order
  
  inv_r = inverse_mod(r, order)
  q = (r_point * s + g * minus_e) * inv_r
  

  public_key = ::BitcoinCigs::PublicKey.new(g, q, compressed)
  addr = public_key_to_bc_address(public_key.ser(), network_version)
  raise ::BitcoinCigs::Error.new("Bad address. Signing: #{addr}, Received: #{address}") if address != addr
  
  nil
end