Class: DSP::TEA

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

Constant Summary collapse

ROUND = 
16
LOG_ROUNDS = 
4
DELTA = 
0x9e3779b9
SALT_LEN = 
2
ZERO_LEN = 
7

Class Method Summary collapse

Class Method Details

.convertByteToInt(content) ⇒ Object 



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# File 'lib/dsp.rb', line 52

def convertByteToInt(content)
  tmp = []
  result = []
  len = content.length
  raise "Invalid length of byte array, must be 4 times." if len % 4 != 0

  for i in 0...(len / 4)
    tmp[0,4] = content[i*4, 4]
    result[i] = ntohl(tmp)
  end

  return result
end

.convertIntToByte(content) ⇒ Object 



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# File 'lib/dsp.rb', line 66

def convertIntToByte(content)
  result = []
  for i in (0...content.length)
    tmp = htonl(content[i])
    # System.arraycopy(tmp, 0, result, i * 4, 4)
    result[i*4, 4] = tmp[0, 4]
  end
  return result
end

.decrypt(encryptContent, key) ⇒ Object 



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# File 'lib/dsp.rb', line 22

def decrypt(encryptContent, key)
  con = convertByteToInt(encryptContent)
  k = convertByteToInt(key)
  y = getUnsignedInt(con[0])
  z = getUnsignedInt(con[1])
  sum = 0
  a = k[0]
  b = k[1]
  c = k[2]
  d = k[3]
  sum = getUnsignedInt(0x9e3779b9 << LOG_ROUNDS)
  delta = getUnsignedInt(0x9e3779b9)
  for i in (0...ROUND)
    z -= (y << 4) + c ^ y + sum ^ (y >> 5) + d
    z &= 0xffffffff
    y -= (z << 4) + a ^ z + sum ^ (z >> 5) + b
    y &= 0xffffffff
    sum -= delta
    sum &= 0xffffffff
  end

  con[0] = y | 0x0
  con[1] = z | 0x0
  return convertIntToByte(con)
end

.decryptData(pInBuf, pKey) ⇒ Object 



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# File 'lib/dsp.rb', line 96

def decryptData( pInBuf,  pKey)
  nBufPos = 0
  dest_buf = []
  zero_buf = []
  cur_buf = []
  nInBufLen = pInBuf.length
  return nil if nInBufLen % 8 != 0 || nInBufLen < 16 || pKey.length != 16
  cur_buf[0,8] = pInBuf[0,8]
  dest_buf = decrypt(cur_buf, pKey)
  nPadLen = dest_buf[0] & 7
  textLen = nInBufLen - 1 - nPadLen - 2 - 7
  pOutBufLen = textLen
  pOutBuf = []

  for i in (0...pOutBufLen)
    pOutBuf[i] = 48
  end

  for i in (0...8)
    zero_buf[i] = 0
  end

  iv_pre_crypt = zero_buf.clone
  iv_cur_crypt = cur_buf.clone
  nBufPos += 8
  cur_buf[0, 8] = pInBuf[8, 8]
  dest_i = 1
  dest_i += nPadLen

  i = 1
  while i <= 2
    if(dest_i < 8)
      dest_i += 1
      i += 1
    elsif(dest_i == 8)
      iv_pre_crypt = iv_cur_crypt.clone
      iv_cur_crypt = cur_buf.clone
      for j in (0...8)
        return nil if (nBufPos + j >= nInBufLen)
        dest_buf[j] ^= pInBuf[nBufPos + j]
      end
      dest_buf = decrypt(dest_buf, pKey)
      nBufPos += 8
      cur_buf[0, 8] = pInBuf[16, 8]
      dest_i = 0
    end
  end
  nPlainLen = pOutBufLen
  i = 0
  while nPlainLen > 0
    if(dest_i < 8)
      pOutBuf[i+=1] = dest_buf[dest_i] ^ iv_pre_crypt[dest_i]
      dest_i+=1
      nPlainLen-=1
    elsif(dest_i == 8)
      iv_pre_crypt = iv_cur_crypt.clone
      iv_cur_crypt = cur_buf.clone
      for j in (0...8)
        return nil if(nBufPos + j >= nInBufLen)
        dest_buf[j] ^= pInBuf[nBufPos + j]
      end
      dest_buf = decrypt(dest_buf, pKey)
      nBufPos += 8
      dest_i = 0
    end
  end
  i = 1
  while i <= 7
    if(dest_i < 8)
      if((dest_buf[dest_i] ^ iv_pre_crypt[dest_i]) != 1)
        dest_i+=1
        i+=1
      else
        return nil
      end
    elsif(dest_i == 8)
      iv_pre_crypt = iv_cur_crypt.clone
      iv_cur_crypt = cur_buf.clone
      for j in (0...8)
        return nil if(nBufPos + j >= nInBufLen)
        dest_buf[j] ^= pInBuf[j]
      end
      dest_buf = decrypt(dest_buf, pKey)
      nBufPos += 8
      dest_i = 0
    end
  end

  return pOutBuf
end

.decryptString(encryptedStr, key) ⇒ Object 



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# File 'lib/dsp.rb', line 187

def decryptString(encryptedStr , key)
  infoStr = Base64.decode64(encryptedStr).bytes
  bKey = key.bytes
  res = decryptData(infoStr, bKey)
  res.pack('c*')
end

.getUnsignedInt(data) ⇒ Object 



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# File 'lib/dsp.rb', line 48

def getUnsignedInt(data)
  return data & 0xffffffff
end

.htonl(x) ⇒ Object 



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# File 'lib/dsp.rb', line 76

def htonl(x)
  res = []
  for i in (0...4)
    res[i] = x >> 24 & 0xff
    x <<= 8
  end

  return res
end

.ntohl(x) ⇒ Object 



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# File 'lib/dsp.rb', line 86

def ntohl(x)
  res = 0
  for i in (0...4)
    res <<= 8
    res |= 0xff & x[i]
  end

  return res
end