Class: IPCrypt::ND

Inherits:
Object
  • Object
show all
Defined in:
lib/ipcrypt/nd.rb

Overview

Implementation of ipcrypt-nd using KIASU-BC

Constant Summary collapse

SBOX =

AES S-box and inverse S-box

[
  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
].freeze
INV_SBOX = 
[
  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
  0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
  0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
  0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
  0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
  0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
  0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
  0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
  0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
  0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
  0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
  0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
  0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
  0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
  0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
].freeze
RCON =

AES round constants

[0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36].freeze
MUL2 =

Precomputed multiplication tables for AES operations

(0..255).map do |x|
  ((x << 1) & 0xFF) ^ (x & 0x80 != 0 ? 0x1B : 0)
end.freeze
MUL3 = 
(0..255).map do |x|
  MUL2[x] ^ x
end.freeze

Class Method Summary collapse

Class Method Details

.bytes_to_ip(bytes16) ⇒ Object

Convert a 16-byte representation back to an IP address

Raises:



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# File 'lib/ipcrypt/nd.rb', line 97

def self.bytes_to_ip(bytes16)
  raise InvalidDataError, 'Input must be 16 bytes' unless bytes16.length == 16

  # Check for IPv4-mapped IPv6 format
  zero_bytes = [0] * 10
  ff_bytes = [255, 255]

  if bytes16[0, 10].bytes == zero_bytes && bytes16[10, 2].bytes == ff_bytes
    IPAddr.new_ntoh(bytes16[12, 4])
  else
    IPAddr.new_ntoh(bytes16)
  end
end

.decrypt(encrypted_data, key) ⇒ Object

Decrypt an IP address using ipcrypt-nd

Raises:



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# File 'lib/ipcrypt/nd.rb', line 293

def self.decrypt(encrypted_data, key)
  raise InvalidDataError, 'Encrypted data must be 24 bytes' unless encrypted_data.length == 24

  # Split into tweak and ciphertext
  tweak = encrypted_data[0, 8]
  ciphertext = encrypted_data[8, 16]

  # Decrypt using KIASU-BC
  ip_bytes = kiasu_bc_decrypt(key, tweak, ciphertext)

  # Convert back to IP address
  bytes_to_ip(ip_bytes)
end

.encrypt(ip_address, key, tweak = nil) ⇒ Object

Encrypt an IP address using ipcrypt-nd



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# File 'lib/ipcrypt/nd.rb', line 274

def self.encrypt(ip_address, key, tweak = nil)
  # Convert IP to bytes
  ip_bytes = ip_to_bytes(ip_address)

  # Use provided tweak or generate random 8-byte tweak
  if tweak.nil?
    tweak = OpenSSL::Random.random_bytes(8)
  elsif tweak.length != 8
    raise InvalidTweakError, 'Tweak must be 8 bytes'
  end

  # Encrypt using KIASU-BC
  ciphertext = kiasu_bc_encrypt(key, tweak, ip_bytes)

  # Return tweak || ciphertext
  tweak + ciphertext
end

.expand_key(key) ⇒ Object

Generate AES round keys

Raises:



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# File 'lib/ipcrypt/nd.rb', line 117

def self.expand_key(key)
  raise InvalidKeyError, 'Key must be 16 bytes' unless key.length == 16

  round_keys = [key]
  10.times do |i|
    prev_key = round_keys.last
    temp = prev_key[-4..]
    temp = rot_word(temp)
    temp = temp.bytes.map { |b| SBOX[b] }.pack('C*')
    temp[0] = (temp[0].ord ^ RCON[i]).chr

    new_key = ''
    4.times do |j|
      word = prev_key[j * 4, 4]
      word = if j.zero?
               word.bytes.zip(temp.bytes).map { |a, b| a ^ b }.pack('C*')
             else
               word.bytes.zip(new_key[(j - 1) * 4, 4].bytes).map { |a, b| a ^ b }.pack('C*')
             end
      new_key += word
    end
    round_keys << new_key
  end

  round_keys
end

.gf_mul_09(a) ⇒ Object

Specialized GF multiplication by 0x09 (x^3 + 1)



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# File 'lib/ipcrypt/nd.rb', line 61

def self.gf_mul_09(a)
  # 0x09 = x^3 + 1 = MUL2[MUL2[MUL2[a]]] ^ a
  MUL2[MUL2[MUL2[a]]] ^ a
end

.gf_mul_0b(a) ⇒ Object

Specialized GF multiplication by 0x0B (x^3 + x + 1)



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# File 'lib/ipcrypt/nd.rb', line 67

def self.gf_mul_0b(a)
  # 0x0B = x^3 + x + 1 = MUL2[MUL2[MUL2[a]]] ^ MUL2[a] ^ a
  MUL2[MUL2[MUL2[a]]] ^ MUL2[a] ^ a
end

.gf_mul_0d(a) ⇒ Object

Specialized GF multiplication by 0x0D (x^3 + x^2 + 1)



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# File 'lib/ipcrypt/nd.rb', line 73

def self.gf_mul_0d(a)
  # 0x0D = x^3 + x^2 + 1 = MUL2[MUL2[MUL2[a]]] ^ MUL2[MUL2[a]] ^ a
  MUL2[MUL2[MUL2[a]]] ^ MUL2[MUL2[a]] ^ a
end

.gf_mul_0e(a) ⇒ Object

Specialized GF multiplication by 0x0E (x^3 + x^2 + x)



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# File 'lib/ipcrypt/nd.rb', line 79

def self.gf_mul_0e(a)
  # 0x0E = x^3 + x^2 + x = MUL2[MUL2[MUL2[a]]] ^ MUL2[MUL2[a]] ^ MUL2[a]
  MUL2[MUL2[MUL2[a]]] ^ MUL2[MUL2[a]] ^ MUL2[a]
end

.inv_mix_columns(state) ⇒ Object

Perform inverse AES MixColumns operation



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# File 'lib/ipcrypt/nd.rb', line 200

def self.inv_mix_columns(state)
  new_state = []
  4.times do |i|
    col = state[i * 4, 4].bytes
    result = [
      gf_mul_0e(col[0]) ^ gf_mul_0b(col[1]) ^ gf_mul_0d(col[2]) ^ gf_mul_09(col[3]),
      gf_mul_09(col[0]) ^ gf_mul_0e(col[1]) ^ gf_mul_0b(col[2]) ^ gf_mul_0d(col[3]),
      gf_mul_0d(col[0]) ^ gf_mul_09(col[1]) ^ gf_mul_0e(col[2]) ^ gf_mul_0b(col[3]),
      gf_mul_0b(col[0]) ^ gf_mul_0d(col[1]) ^ gf_mul_09(col[2]) ^ gf_mul_0e(col[3])
    ]
    new_state += result
  end
  new_state.pack('C*')
end

.inv_shift_rows(state) ⇒ Object

Perform inverse AES ShiftRows operation



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# File 'lib/ipcrypt/nd.rb', line 177

def self.inv_shift_rows(state)
  bytes = state.bytes
  [
    bytes[0], bytes[13], bytes[10], bytes[7], bytes[4], bytes[1], bytes[14], bytes[11],
    bytes[8], bytes[5], bytes[2], bytes[15], bytes[12], bytes[9], bytes[6], bytes[3]
  ].pack('C*')
end

.inv_sub_bytes(state) ⇒ Object

Perform inverse AES SubBytes operation



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# File 'lib/ipcrypt/nd.rb', line 163

def self.inv_sub_bytes(state)
  state.bytes.map { |b| INV_SBOX[b] }.pack('C*')
end

.ip_to_bytes(ip) ⇒ Object

Convert an IP address to its 16-byte representation



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# File 'lib/ipcrypt/nd.rb', line 85

def self.ip_to_bytes(ip)
  ip_addr = ip.is_a?(String) ? IPAddr.new(ip) : ip
  if ip_addr.ipv4?
    # Convert IPv4 to IPv4-mapped IPv6 format (::ffff:0:0/96)
    bytes = [0] * 10 + [0xff, 0xff] + ip_addr.hton.bytes
    bytes.pack('C*').force_encoding('BINARY')
  else
    ip_addr.hton.force_encoding('BINARY')
  end
end

.kiasu_bc_decrypt(key, tweak, ciphertext) ⇒ Object

Decrypt using KIASU-BC construction

Raises:



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# File 'lib/ipcrypt/nd.rb', line 245

def self.kiasu_bc_decrypt(key, tweak, ciphertext)
  raise InvalidKeyError, 'Key must be 16 bytes' unless key.length == 16
  raise InvalidTweakError, 'Tweak must be 8 bytes' unless tweak.length == 8
  raise InvalidDataError, 'Ciphertext must be 16 bytes' unless ciphertext.length == 16

  round_keys = expand_key(key)
  padded_tweak = pad_tweak(tweak)

  # Initial operations
  state = ciphertext.bytes.zip(round_keys[10].bytes, padded_tweak.bytes)
                    .map { |c, k, t| c ^ k ^ t }.pack('C*')
  state = inv_shift_rows(state)
  state = inv_sub_bytes(state)

  9.downto(1) do |i|
    # XOR with round key and padded tweak
    state = state.bytes.zip(round_keys[i].bytes, padded_tweak.bytes)
                 .map { |s, k, t| s ^ k ^ t }.pack('C*')
    state = inv_mix_columns(state)
    state = inv_shift_rows(state)
    state = inv_sub_bytes(state)
  end

  # Final round - XOR with round key and padded tweak
  state.bytes.zip(round_keys[0].bytes, padded_tweak.bytes)
       .map { |s, k, t| s ^ k ^ t }.pack('C*')
end

.kiasu_bc_encrypt(key, tweak, plaintext) ⇒ Object

Encrypt using KIASU-BC construction

Raises:



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# File 'lib/ipcrypt/nd.rb', line 216

def self.kiasu_bc_encrypt(key, tweak, plaintext)
  raise InvalidKeyError, 'Key must be 16 bytes' unless key.length == 16
  raise InvalidTweakError, 'Tweak must be 8 bytes' unless tweak.length == 8
  raise InvalidDataError, 'Plaintext must be 16 bytes' unless plaintext.length == 16

  round_keys = expand_key(key)
  padded_tweak = pad_tweak(tweak)

  # XOR plaintext with round key and padded tweak
  state = plaintext.bytes.zip(round_keys[0].bytes, padded_tweak.bytes)
                   .map { |p, k, t| p ^ k ^ t }.pack('C*')

  9.times do |i|
    state = sub_bytes(state)
    state = shift_rows(state)
    state = mix_columns(state)
    # XOR with round key and padded tweak
    state = state.bytes.zip(round_keys[i + 1].bytes, padded_tweak.bytes)
                 .map { |s, k, t| s ^ k ^ t }.pack('C*')
  end

  state = sub_bytes(state)
  state = shift_rows(state)
  # Final round - XOR with round key and padded tweak
  state.bytes.zip(round_keys[10].bytes, padded_tweak.bytes)
       .map { |s, k, t| s ^ k ^ t }.pack('C*')
end

.mix_columns(state) ⇒ Object

Perform AES MixColumns operation



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# File 'lib/ipcrypt/nd.rb', line 186

def self.mix_columns(state)
  new_state = []
  4.times do |i|
    s = state[i * 4, 4].bytes
    s0, s1, s2, s3 = s
    new_state[i * 4] = MUL2[s0] ^ MUL3[s1] ^ s2 ^ s3
    new_state[i * 4 + 1] = s0 ^ MUL2[s1] ^ MUL3[s2] ^ s3
    new_state[i * 4 + 2] = s0 ^ s1 ^ MUL2[s2] ^ MUL3[s3]
    new_state[i * 4 + 3] = MUL3[s0] ^ s1 ^ s2 ^ MUL2[s3]
  end
  new_state.pack('C*')
end

.pad_tweak(tweak) ⇒ Object

Pad an 8-byte tweak to 16 bytes by placing each 2-byte pair at the start of each 4-byte group

Raises:



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# File 'lib/ipcrypt/nd.rb', line 145

def self.pad_tweak(tweak)
  raise InvalidTweakError, 'Tweak must be 8 bytes' unless tweak.length == 8

  padded_bytes = [0] * 16
  4.times do |i|
    padded_bytes[i * 4] = tweak[i * 2].ord
    padded_bytes[i * 4 + 1] = tweak[i * 2 + 1].ord
    # padded_bytes[i * 4 + 2] and padded_bytes[i * 4 + 3] are already 0
  end
  padded_bytes.pack('C*').force_encoding('BINARY')
end

.rot_word(word) ⇒ Object

Rotate a 4-byte word



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# File 'lib/ipcrypt/nd.rb', line 112

def self.rot_word(word)
  word[1..] + word[0]
end

.shift_rows(state) ⇒ Object

Perform AES ShiftRows operation



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# File 'lib/ipcrypt/nd.rb', line 168

def self.shift_rows(state)
  bytes = state.bytes
  [
    bytes[0], bytes[5], bytes[10], bytes[15], bytes[4], bytes[9], bytes[14], bytes[3],
    bytes[8], bytes[13], bytes[2], bytes[7], bytes[12], bytes[1], bytes[6], bytes[11]
  ].pack('C*')
end

.sub_bytes(state) ⇒ Object

Perform AES SubBytes operation



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# File 'lib/ipcrypt/nd.rb', line 158

def self.sub_bytes(state)
  state.bytes.map { |b| SBOX[b] }.pack('C*')
end