Class: Warchat::Srp::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/warchat/srp/client.rb

Constant Summary collapse

G = 
2
MODULUS_SIZE = 
128
MODULUS = 
0x86a7f6deeb306ce519770fe37d556f29944132554ded0bd68205e27f3231fef5a10108238a3150c59caf7b0b6478691c13a6acf5e1b5adafd4a943d4a21a142b800e8a55f8bfbac700eb77a7235ee5a609e350ea9fc19f10d921c2fa832e4461b7125d38d254a0be873dfc27858acb3f8b9f258461e4373bc3a6c2a9634324ab
SALT_SIZE = 
32
HASH_SIZE = 
32
SESSION_KEY_SIZE = 
HASH_SIZE * 2

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#b ⇒ Object (readonly)

Returns the value of attribute b.



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# File 'lib/warchat/srp/client.rb', line 17

def b
  @b
end

#b_bytes ⇒ Object (readonly)

Returns the value of attribute b_bytes.



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# File 'lib/warchat/srp/client.rb', line 17

def b_bytes
  @b_bytes
end

#password ⇒ Object (readonly)

Returns the value of attribute password.



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# File 'lib/warchat/srp/client.rb', line 17

def password
  @password
end

#salt ⇒ Object (readonly)

Returns the value of attribute salt.



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# File 'lib/warchat/srp/client.rb', line 17

def salt
  @salt
end

#user ⇒ Object (readonly)

Returns the value of attribute user.



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# File 'lib/warchat/srp/client.rb', line 17

def user
  @user
end

Instance Method Details

#a ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 66

def a
  @a ||= random_crypt
end

#a_bytes ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 70

def a_bytes 
  @a_bytes ||= adjust_size(pack_int(modpow(G,a,MODULUS)),MODULUS_SIZE)
end

#adjust_size(str, length) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 45

def adjust_size str,length
  Warchat::ByteString.new  str[0..(length-1)].ljust(length,"\000")
end

#auth1_proof(user, password, salt, b_bytes) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 98

def auth1_proof user, password, salt, b_bytes
  @b = unpack_int b_bytes
  
  @b_bytes = adjust_size(b_bytes,MODULUS_SIZE)
  @salt = adjust_size(salt,SALT_SIZE)
  @user = user
  @password = password

  proof
end

#digest_int(s) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 37

def digest_int s
  unpack_int(digest_str(s))
end

#digest_str(s) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 41

def digest_str s
  Digest::SHA2.digest(s).tap do |s| s.respond_to? :force_encoding and s.force_encoding(__ENCODING__) end
end

#hN_xor_hG ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 53

def hN_xor_hG
  # xor H(N) and H(G)
  return @hN_xor_hG if @hN_xor_hG
  hN = digest_str(pack_int(MODULUS)).unpack('C*')
  hG = digest_str(pack_int(G)).unpack('C*')
  
  tmp = []
  
  HASH_SIZE.times do |i| tmp[i] = (hN[i] ^ hG[i]) end
    
  @hN_xor_hG = tmp.pack('C*')
end

#k ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 74

def k
  @k ||= digest_int(pack_int(MODULUS)+pack_int(G))
end

#modpow(a, n, m) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 19

def modpow(a, n, m) 
  r = 1
  while true
    r = r * a % m if n[0] == 1
    n >>= 1
    return r if n == 0
    a = (a ** 2) % m
  end
end

#pack_int(int) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 29

def pack_int int
  Warchat::ByteString.new([int.to_s(16).reverse].pack('h*'))
end

#proof ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 109

def proof
   # hash this to generate client proof, H(H(N) xor H(G) | H(userHash) | salt | A | B | K)
  Warchat::ByteString.new digest_str(hN_xor_hG+digest_str(user)+salt+a_bytes+b_bytes+session_key)
end

#random_crypt ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 49

def random_crypt
  unpack_int(OpenSSL::Random.random_bytes(MODULUS_SIZE*2)) % MODULUS
end

#s ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 88

def s
  # (B - k * G^x) ^ (a + u * x)
  return modpow(b - k * modpow(G, x, MODULUS), a + u * x, MODULUS)
end

#s_bytes ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 93

def s_bytes
  @s_bytes ||= adjust_size(pack_int(s),(MODULUS_SIZE))
end

#session_key ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 114

def session_key
  return @session_key if @session_key
  @session_key = "\000" * SESSION_KEY_SIZE

  l = s_bytes.length
  offset = (l.odd? and 1 or 0)
  l -= offset

  l = [l/2,MODULUS_SIZE].min

  temp = ''
  l.times do |i|
    temp << s_bytes[i*2+offset]
  end

  hash = digest_str(temp)
  HASH_SIZE.times do |i|
    @session_key[i*2] = hash[i]
  end

  temp = ''
  l.times do |i|
    temp << s_bytes[i*2+offset+1]
  end

  hash = digest_str(temp)
  HASH_SIZE.times do |i|
    @session_key[i*2+1] = hash[i]
  end

  @session_key
end

#u ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 78

def u 
  # H(A | B)
  @u ||= digest_int(a_bytes+b_bytes)
end

#unpack_int(str) ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 33

def unpack_int str
  str.unpack('h*').first.reverse.hex
end

#x ⇒ Object 



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# File 'lib/warchat/srp/client.rb', line 83

def x
  # H(salt | H(userHash | : | sessionPassword))
  @x ||= digest_int(@salt+digest_str(@user+":"+@password))
end