hashcash

Hashcash (hashcash v1.2.0)

Elixir implementation of the hashcash algorigthm as described in http://hashcash.org and https://en.wikipedia.org/wiki/Hashcash

Generate a stamp for another party to generate:

Hashcash.resource("foobar") |> Hashcash.resource_format
%Hashcash{
  bits: 20,
  counter: 0,
  date: [year: 2022, month: 9, day: 2],
  ext: nil,
  rand: "gAbLlrNJFwsKWincKbOvNP6kNkUHRt1",
  resource: "foobar",
  stamp_base: "1:20:220902:foobar::gAbLlrNJFwsKWincKbOvNP6kNkUHRt1",
  stamp_string: "1:20:220902:foobar::gAbLlrNJFwsKWincKbOvNP6kNkUHRt1:0",
  version: 1
}

The stamp_string can be sent to the other party.

To verify:

iex(4)> Hashcash.stamp("1:20:220902:foobar::GszJUJJC+tcQSkvw+GPg7FBYYi289eL:294524") |> Hashcash.verify("foobar")
{:ok, :verified}

Link to this section Summary

Types

t()

Functions

count_lead_zeros_in_bitstring(bs, count \\ 0)

Count leading zero bits in a bitstring

date_format(date_keywords)

Generate date string section from date keywords list

date_now()

Generate date keywords list of now

generate(hcash)

Generate a full stamp, doing the work

rand_generate()

Generate the rand field using a crypto.strong_rand_bytes

resource(resource_string)

Create a new %Hashcash with resource_string and today as the date.

resource(resource_string, date)

Create a new %Hashcash with the resource_string and specified date Keyword list

resource_bits(hcash, bits)

Modify the bits required of a %Hashcash

resource_date(hcash, y, m, d)

Modify the date of a %Hashcash

resource_format(hcash)

Return %Hashcash with stamp_base and stamp_string set.

resource_format_base(hcash)

Generate or return hcash.base from properies This excludes the count field so that the generator can use this base with successive iterations of new counts by appending just the count.

resource_format_string(base, counter)

Append the counter to the base to make a full stamp string

resource_rand(hcash)

Set rand field of %Hashcash to newly generated string

stamp(stamp_string)

Create a %Hashcash stamp from a stamp string. Use this to turn a string that may be passed between parties to a form that can be used with the rest of the functions here.

strip_trailing_char(string)
validate(hcash)

Validate the stamp string proof-of-work only. Use verify for full check

verify(hcash, valid_resources)

Verfiy all attributes and proof of work against a list of acceptable resources or a single resource string

verify_resource(resource, valid_resources)

Verify stamp resource is a valid resource

verify_time(date)

Verify date keyword list is within 2 days

zero_bits_count(hcash)

Count leading zero bits in SHA1 hash of stamp.stamp_string

Link to this section Types

Link to this type

t()

@type t() :: %Hashcash{
  bits: term(),
  counter: term(),
  date: term(),
  ext: term(),
  rand: term(),
  resource: term(),
  stamp_base: term(),
  stamp_string: term(),
  version: term()
}

Link to this section Functions

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count_lead_zeros_in_bitstring(bs, count \\ 0)

@spec count_lead_zeros_in_bitstring(bs :: String.t(), count :: integer()) :: integer()

Count leading zero bits in a bitstring

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date_format(date_keywords)

@spec date_format(date_keywords :: Keyword.t()) :: String.t()

Generate date string section from date keywords list

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date_now()

@spec date_now() :: Keyword.t()

Generate date keywords list of now

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generate(hcash)

@spec generate(hcash :: t()) :: t()

Generate a full stamp, doing the work

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rand_generate()

@spec rand_generate() :: String.t()

Generate the rand field using a crypto.strong_rand_bytes

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resource(resource_string)

@spec resource(resource_string :: String.t()) :: t()

Create a new %Hashcash with resource_string and today as the date.

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resource(resource_string, date)

@spec resource(resource_string :: String.t(), date :: Keyword.t()) :: t()

Create a new %Hashcash with the resource_string and specified date Keyword list

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resource_bits(hcash, bits)

@spec resource_bits(hcash :: t(), bits :: integer()) :: t()

Modify the bits required of a %Hashcash

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resource_date(hcash, y, m, d)

@spec resource_date(hcash :: t(), y :: integer(), m :: integer(), d :: integer()) ::
  t()

Modify the date of a %Hashcash

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resource_format(hcash)

@spec resource_format(hcash :: t()) :: t()

Return %Hashcash with stamp_base and stamp_string set.

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resource_format_base(hcash)

@spec resource_format_base(hcash :: t()) :: String.t()

Generate or return hcash.base from properies This excludes the count field so that the generator can use this base with successive iterations of new counts by appending just the count.

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resource_format_string(base, counter)

@spec resource_format_string(base :: String.t(), counter :: integer()) :: String.t()

Append the counter to the base to make a full stamp string

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resource_rand(hcash)

@spec resource_rand(stamp :: t()) :: t()

Set rand field of %Hashcash to newly generated string

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stamp(stamp_string)

Create a %Hashcash stamp from a stamp string. Use this to turn a string that may be passed between parties to a form that can be used with the rest of the functions here.

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strip_trailing_char(string)

@spec strip_trailing_char(string :: String.t()) :: String.t()
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validate(hcash)

@spec validate(hcash :: t()) :: tuple()

Validate the stamp string proof-of-work only. Use verify for full check

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verify(hcash, valid_resources)

@spec verify(hcash :: t(), valid_resources :: list()) :: tuple()
@spec verify(hcash :: t(), single_resource :: String.t()) :: tuple()

Verfiy all attributes and proof of work against a list of acceptable resources or a single resource string

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verify_resource(resource, valid_resources)

@spec verify_resource(resource :: String.t(), valid_resources :: list()) :: tuple()

Verify stamp resource is a valid resource

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verify_time(date)

@spec verify_time(date :: Keyword.t()) :: tuple()

Verify date keyword list is within 2 days

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zero_bits_count(hcash)

@spec zero_bits_count(hcash :: t()) :: integer()

Count leading zero bits in SHA1 hash of stamp.stamp_string