Cafezinho (cafezinho v0.4.2)

NIF for Ed25519 curve functions.

It uses https://github.com/brndnmtthws/dryoc

Summary

Functions

generate()

Generate a random keypair

keypair_from_seed(seed)

Create a keypair from seed

sign(data, secret_key)

Sign data with a secret key

verify(signature, message, public_key)

Verify a signature

Functions

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generate()

@spec generate() :: {binary(), binary()}

Generate a random keypair

Examples 

iex> {<<_public_key::binary-size(32)>>, <<_secret_key::binary-size(64)>>} = Cafezinho.generate()
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keypair_from_seed(seed)

@spec keypair_from_seed(binary()) :: {:ok, {binary(), binary()}} | {:error, atom()}

Create a keypair from seed

Examples 

iex> seed = <<216, 145, 38, 65, 213, 88, 1, 110, 133, 87, 170, 172, 147, 33, 96, 73, 164, 121, 52, 37, 94, 100, 25, 147, 124, 8, 232, 161, 104, 122, 232, 44>>
iex> {:ok, {_public_key, _secret_key}} = Cafezinho.keypair_from_seed(seed)
{:ok,
  {<<218, 140, 98, 244, 76, 48, 223, 187, 117, 177, 228, 75, 120, 10, 202, 138,
     48, 149, 51, 209, 225, 87, 148, 132, 229, 110, 178, 4, 19, 205, 1, 218>>,
   <<216, 145, 38, 65, 213, 88, 1, 110, 133, 87, 170, 172, 147, 33, 96, 73, 164,
     121, 52, 37, 94, 100, 25, 147, 124, 8, 232, 161, 104, 122, 232, 44, 218,
     140, 98, 244, 76, 48, 223, 187, 117, 177, 228, 75, 120, 10, 202, 138, 48,
     149, 51, 209, 225, 87, 148, 132, 229, 110, 178, 4, 19, 205, 1, 218>>}}

iex> Cafezinho.keypair_from_seed(<<1>>)
{:error, :wrong_seed_size}
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sign(data, secret_key)

@spec sign(binary(), binary()) :: {:ok, binary()} | {:error, atom()}

Sign data with a secret key

Examples 

iex> secret_key = <<216, 145, 38, 65, 213, 88, 1, 110, 133, 87, 170, 172, 147, 33, 96, 73, 164, 121, 52, 37, 94, 100, 25, 147, 124, 8, 232, 161, 104, 122, 232, 44, 218, 140, 98, 244, 76, 48, 223, 187, 117, 177, 228, 75, 120, 10, 202, 138, 48, 149, 51, 209, 225, 87, 148, 132, 229, 110, 178, 4, 19, 205, 1, 218>>
iex> Cafezinho.sign(<<1>>, secret_key)
{:ok,
 <<51, 122, 38, 168, 118, 176, 54, 245, 199, 189, 126, 196, 119, 78, 149, 111,
   125, 5, 46, 219, 166, 158, 141, 137, 68, 236, 151, 104, 101, 191, 138, 78,
   53, 119, 225, 244, 115, 101, 250, 155, 3, 177, 193, 130, 141, 19, 13, 30, 14,
   18, 177, 153, 84, 70, 137, 156, 114, 97, 174, 138, 138, 154, 230, 10>>}

iex> Cafezinho.sign(<<1>>, <<1>>)
{:error, :wrong_secret_key_size}
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verify(signature, message, public_key)

@spec verify(binary(), binary(), binary()) :: :ok | {:error, atom()}

Verify a signature

Examples 

iex> signature =  <<188, 159, 33, 122, 42, 62, 50, 237, 156, 38, 95, 81, 116, 233, 254, 0, 113, 220, 29, 152, 198, 72, 126, 188, 85, 239, 86, 29, 26, 182, 11, 208, 25, 30, 189, 99, 92, 76, 42, 245, 1, 116, 24, 179, 247, 221, 20, 178, 225, 31, 88, 175, 42, 250, 66, 0, 212, 98, 24, 184, 61, 216, 8, 3>>
iex> message = "hello"
iex> public_key = <<23, 99, 168, 199, 198, 90, 121, 227, 169, 127, 53, 174, 114, 190, 61, 47, 53, 134, 214, 246, 207, 46, 83, 75, 163, 249, 253, 145, 4, 11, 87, 190>>
iex> Cafezinho.verify(signature, message, public_key)
:ok

iex> Cafezinho.verify("signature", "bye", "public_key")
{:error, :wrong_signature_size}