Class: SJCL::Cipher::AES

Inherits:
Object
  • Object
show all
Defined in:
lib/sjcl/aes.rb

Constant Summary collapse

TABLES = 
SJCL::Cipher::AES_Tables::TABLES

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key) ⇒ AES

Returns a new instance of AES.



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# File 'lib/sjcl/aes.rb', line 8

def initialize(key)
  @raw_key = key
  @keyLen = key.length
  schedule_keys
end

Instance Attribute Details

#key ⇒ Object (readonly)

Returns the value of attribute key.



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# File 'lib/sjcl/aes.rb', line 6

def key
  @key
end

Instance Method Details

#decrypt(data) ⇒ Object 



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# File 'lib/sjcl/aes.rb', line 56

def decrypt(data)
  crypt(data,1)
end

#encrypt(data) ⇒ Object 



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# File 'lib/sjcl/aes.rb', line 52

def encrypt(data)
  crypt(data,0)
end

#schedule_keys ⇒ Object 



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# File 'lib/sjcl/aes.rb', line 14

def schedule_keys
  sbox = TABLES[0][4]
  decTable = TABLES[1]
  encKey = @raw_key.dup
  decKey = []
  rcon = 1
  i = @keyLen
  j = 0
  while i < 4*@keyLen + 28
    tmp = encKey[i-1] ? encKey[i-1] & 0xFFFFFFFF : 0
    if (i % @keyLen === 0 || (@keyLen === 8 && i % @keyLen === 4))
      tmp = sbox[tmp >> 24] << 24 ^ sbox[tmp >> 16 & 255] << 16 ^ sbox[tmp >> 8 & 255] << 8 ^ sbox[tmp & 255]
      if (i % @keyLen === 0)
        tmp = tmp<<8 ^ tmp >> 24 ^ rcon << 24
        rcon = rcon << 1 ^ (rcon >> 7) * 283
      end
    end
    encKey[i] = (encKey[i-@keyLen] ^ tmp) & 0xFFFFFFFF;
    i += 1
  end
  while i > 0
    tmp = encKey[j & 3 != 0 ? i : i - 4];
    tmp = tmp & 0xFFFFFFFF
    if (i<=4 || j<4)
      decKey[j] = tmp;
    else
      decKey[j] = decTable[0][sbox[tmp >> 24]] ^
      decTable[1][sbox[tmp >> 16 & 255]] ^
      decTable[2][sbox[tmp >> 8 & 255]] ^
      decTable[3][sbox[tmp & 255]]
    end
    decKey[j] = decKey[j] & 0xFFFFFFFF
    i -= 1
    j += 1
  end
  @key = [encKey, decKey]
end