Specs

bits(pos_integer(), pos_integer()) :: float()

Entropy bits for generating a total number of instances with the given risk of repeat

The total size of the instance pool is 2^bits.

Example

iex> Puid.Entropy.bits(10.0e6, 1.0e12)
85.37013046707142

Specs

bits_for_len(non_neg_integer(), atom() | String.t()) ::
  {:ok, non_neg_integer()} | {:error, Error.reason()}

Entropy bits of a string of len generated from characters charset, where charset is either an pre-defined Puid.CharSet or a string of unique characters.

The character set must be comprised of unique symbols, and it is assumed each symbol in the character set has equal probability of occurrence (which maximizes entropy).

Example

iex> Puid.Entropy.bits_for_len(14, :alphanum)
{:ok, 83}

iex> Puid.Entropy.bits_for_len(14, "dingosky")
{:ok, 42}

Specs

bits_for_len!(non_neg_integer(), atom() | String.t()) :: non_neg_integer()

Same as Puid.Entropy.bits_for_len/2 but either returns the integer bits or raises a Puid.Error

Example

iex> Puid.Entropy.bits_for_len!(14, :alphanum)
83

iex> Puid.Entropy.bits_for_len!(14, "dingosky")
42

See Puid.Entropy.bits_for_len/2.

See Puid.Entropy.bits_for_len!/2.

Specs

bits_per_char(atom() | String.t()) :: {:ok, float()} | {:error, Error.reason()}

Entropy bits per character where charset is either an pre-defined Puid.CharSet or a string of unique characters.

The character set must be comprised of unique symbols, and it is assumed each symbol in the character set has equal probability of occurrence (which maximizes entropy).

Returns {:ok, bits}; or {:error, reason} if arg is either an unrecognized pre-defined Puid.CharSet or a string of non-unique characters.

Example

iex> Puid.Entropy.bits_per_char(:alphanum)
{:ok, 5.954196310386875}

iex> Puid.Entropy.bits_per_char("dingosky")
{:ok, 3.0}

Specs

bits_per_char!(atom() | String.t()) :: float()

Same as bits_per_char/1 but either returns the bits or raises a Puid.Error

Example

 iex> Puid.Entropy.bits_per_char!(:alphanum)
 5.954196310386875

 Puid.Entropy.bits_per_char!("dingosky")
 3.0

Specs

len_for_bits(non_neg_integer(), atom() | String.t()) ::
  {:ok, non_neg_integer()} | {:error, Error.reason()}

Length needed for a string generated from charset to have bits of entropy.

The character set must be comprised of unique symbols, and it is assumed each symbol in the character set has equal probability of occurrence (which maximizes entropy).

Example

iex> Puid.Entropy.len_for_bits(128, :alphanum)
{:ok, 22}

iex> Puid.Entropy.len_for_bits(128, "dingosky")
{:ok, 43}

Specs

len_for_bits!(non_neg_integer(), atom() | String.t()) :: non_neg_integer()

Same as Puid.Entropy.len_for_bits/2 but either returns the integer len or raises a Puid.Error

Example

iex> Puid.Entropy.len_for_bits!(128, :alphanum)
22

iex> Puid.Entropy.len_for_bits!(128, "dingosky")
43