natecook1000

/// A dictionary wrapper that uses a `CaseIterable` type as its key.
/// This differs from a dictionary in two ways:
///
/// - Key-value pairs are accessed in a fixed order, which is the same
///   as the `Key`'s `allCases` property.
/// - Every possible key must have a value given, so using the key-based
///   subscript returns a non-optional value.
struct CaseMap<Key: CaseIterable & Hashable, Value> : Collection {
  typealias Index = Key.AllCases.Index

natecook1000

/// Returns a binary predicate using the given key path to create an ascending order
/// for elements of type `Root`.
func ascending<Root, Value: Comparable>(_ path: KeyPath<Root, Value>) -> (Root, Root) -> Bool {
  return { $0[keyPath: path] < $1[keyPath: path] }
}

/// Returns a binary predicate using the given key path to create a descending order
/// for elements of type `Root`.
func descending<Root, Value: Comparable>(_ path: KeyPath<Root, Value>) -> (Root, Root) -> Bool {
  return { $0[keyPath: path] > $1[keyPath: path] }

DougGregor

import Darwin

@dynamicMemberLookup
struct Environment {
  subscript(dynamicMember name: String) -> String? {
    get {
      guard let value = getenv(name) else { return nil }

      return String(validatingUTF8: value)
    }

kallewoof

Schnorr signature test vectors

Test vector overview

1. Hash function H(m) = SHA256(m)

Basics

• For a private key x, the public key is xG.
• A signature on the message m with private key x is (R, s) where R=kG, s=k+H(R,X,m)x.
• Verifying a signature is testing whether sG = R+H(R,X,m)X.

hfossli

#import <CommonCrypto/CommonCrypto.h>

merryhime

Merry's very quick guide to elliptic curve crypto

An elliptic curve is made up of the following:

1. A field, F_p.

• What this means is all arithmetic on scalars is modulo p.
• Modern ECC have p as some large prime.
• For curve25519, p = 2^255 - 19, a prime.

2. An equation and it's parameters:

shihrer

"""
MIT License

Copyright (c) 2016 Michael Shihrer (michael@shihrer.me)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is

stribika

#!/usr/bin/python3 -O

from math import floor, log

def montgomery_ladder(x, n, op, select):
    k = floor(log(n, 2)) + 1
    x1 = x
    x2 = op(x, x)
    for i in range(k - 2, -1, -1):
        bit = 1 if n & (1 << i) else 0

natmchugh

import random

class Montgomery:

    #     B*v^2 = u^3 + A*u^2 + u

    def __init__(self, A, B, p):
        self.A = A
        self.B = B
        self.p = p

natecook1000

import Foundation

extension UnicodeScalar : ForwardIndexType {
    public func successor() -> UnicodeScalar {
        return UnicodeScalar(value + 1)
    }
}

var operatorHeads: [UnicodeScalar] = Array("=-+!*%<>&|^~?".unicodeScalars)
operatorHeads += Array("\u{00A1}" ... "\u{00A7}")