118 lines
3.3 KiB
Ruby
118 lines
3.3 KiB
Ruby
# frozen_string_literal: true
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require 'ecdsa'
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require 'securerandom'
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module Nostr
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# Generates private keys, public keys and key pairs.
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class Keygen
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# Instantiates a new keygen
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#
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# @api public
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#
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# @example
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# keygen = Nostr::Keygen.new
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#
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def initialize
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@group = ECDSA::Group::Secp256k1
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end
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# Generates a pair of private and public keys
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#
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# @api public
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#
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# @example
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# keypair = keygen.generate_keypair
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# keypair # #<Nostr::KeyPair:0x0000000107bd3550
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# @private_key="893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900",
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# @public_key="2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558">
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#
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# @return [KeyPair] An object containing a private key and a public key.
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#
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def generate_key_pair
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private_key = generate_private_key
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public_key = extract_public_key(private_key)
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KeyPair.new(private_key:, public_key:)
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end
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# Generates a private key
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#
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# @api public
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#
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# @example
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# private_key = keygen.generate_private_key
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# private_key # => '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'
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#
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# @return [PrivateKey] A 32-bytes hex-encoded private key.
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#
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def generate_private_key
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hex_value = (SecureRandom.random_number(group.order - 1) + 1).to_s(16).rjust(64, '0')
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PrivateKey.new(hex_value)
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end
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# Extracts a public key from a private key
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#
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# @api public
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#
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# @example
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# private_key = keygen.generate_private_key
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# public_key = keygen.extract_public_key(private_key)
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# public_key # => '2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558'
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#
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# @param [PrivateKey] private_key A 32-bytes hex-encoded private key.
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#
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# @raise [ArgumentError] if the private key is not an instance of +PrivateKey+
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#
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# @return [PublicKey] A 32-bytes hex-encoded public key.
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#
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def extract_public_key(private_key)
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validate_private_key(private_key)
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hex_value = group.generator.multiply_by_scalar(private_key.to_i(16)).x.to_s(16).rjust(64, '0')
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PublicKey.new(hex_value)
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end
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# Builds a key pair from an existing private key
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#
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# @api public
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#
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# @example
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# private_key = Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900')
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# keygen.get_key_pair_from_private_key(private_key)
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#
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# @param private_key [PrivateKey] 32-bytes hex-encoded private key.
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#
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# @raise [ArgumentError] if the private key is not an instance of +PrivateKey+
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#
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# @return [Nostr::KeyPair]
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#
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def get_key_pair_from_private_key(private_key)
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validate_private_key(private_key)
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public_key = extract_public_key(private_key)
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KeyPair.new(private_key:, public_key:)
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end
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private
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# The elliptic curve group. Used to generate public and private keys
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#
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# @api private
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#
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# @return [ECDSA::Group]
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#
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attr_reader :group
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# Validates that the private key is an instance of +PrivateKey+
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#
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# @api private
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#
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# @raise [ArgumentError] if the private key is not an instance of +PrivateKey+
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#
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# @return [void]
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#
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def validate_private_key(private_key)
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raise ArgumentError, 'private_key is not an instance of PrivateKey' unless private_key.is_a?(Nostr::PrivateKey)
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end
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end
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end
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