add password generator

vendor/github.com/sethvargo/go-diceware/LICENSE

@@ -0,0 +1,20 @@
+Copyright 2017 Seth Vargo <seth@sethvargo.com>
+
+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 furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/sethvargo/go-diceware/diceware/generate.go

@@ -0,0 +1,195 @@
+package diceware
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+	"math"
+	"math/big"
+)
+
+// sides is the number of sides on a die.
+var sides = big.NewInt(6)
+
+var _ DicewareGenerator = (*Generator)(nil)
+
+// Generator is the stateful generator which can be used to customize the word
+// list and other generation options.
+type Generator struct {
+	wordList   WordList
+	randReader io.Reader
+}
+
+// GeneratorInput is used as input to the NewGenerator function.
+type GeneratorInput struct {
+	// WordList is the word list to use. There are built-in word lists like
+	// WordListEffBig (default), WordListEffSmall, and WordListOriginal. You can
+	// also bring your own word list by implementing the WordList interface.
+	WordList WordList
+
+	// RandReader is an optional reader to use in place of the default
+	// (crypto/rand.Reader), which can be used to generate repeatable sets of
+	// words
+	RandReader io.Reader
+}
+
+// NewGenerator creates a new Generator from the specified configuration. If no
+// input is given, all the default values are used. This function is safe for
+// concurrent use.
+func NewGenerator(i *GeneratorInput) (*Generator, error) {
+	if i == nil {
+		i = new(GeneratorInput)
+	}
+
+	if i.WordList == nil {
+		i.WordList = WordListEffLarge()
+	}
+
+	gen := &Generator{
+		wordList:   i.WordList,
+		randReader: i.RandReader,
+	}
+
+	if gen.randReader == nil {
+		gen.randReader = rand.Reader
+	}
+
+	return gen, nil
+}
+
+// Generate generates a collection of diceware words, specified by the numWords
+// parameter.
+//
+// The algorithm is fast, but it's not designed to be performant, favoring
+// entropy over speed.
+//
+// This function is safe for concurrent use, but there is a possibility of
+// concurrent invocations generating overlapping words. To generate multiple
+// non-overlapping words, use a single invocation of the function and split the
+// resulting string list.
+func (g *Generator) Generate(numWords int) ([]string, error) {
+	if typ, ok := g.wordList.(WordListNumWordser); ok {
+		if l := typ.NumWords(); numWords > l {
+			return nil, fmt.Errorf("number of requested words (%d) cannot exceed the size of the wordlist (%d)",
+				numWords, l)
+		}
+	}
+
+	list := make([]string, 0, numWords)
+	seen := make(map[string]struct{}, numWords)
+
+	for i := 0; i < numWords; i++ {
+		n, err := g.RollWord(g.wordList.Digits())
+		if err != nil {
+			return nil, err
+		}
+
+		word := g.wordList.WordAt(n)
+		if _, ok := seen[word]; ok {
+			i--
+			continue
+		}
+
+		list = append(list, word)
+		seen[word] = struct{}{}
+	}
+
+	return list, nil
+}
+
+// MustGenerate is the same as Generate, but panics on error.
+func (g *Generator) MustGenerate(numWords int) []string {
+	list, err := g.Generate(numWords)
+	if err != nil {
+		panic(err)
+	}
+	return list
+}
+
+// Generate - see Generator.Generate for usage.
+func Generate(numWords int) ([]string, error) {
+	gen, err := NewGenerator(nil)
+	if err != nil {
+		return nil, err
+	}
+	return gen.Generate(numWords)
+}
+
+// MustGenerate - see Generator.MustGenerate for usage.
+func MustGenerate(numWords int) []string {
+	gen, err := NewGenerator(nil)
+	if err != nil {
+		panic(err)
+	}
+	return gen.MustGenerate(numWords)
+}
+
+// GenerateWithWordList generates a list of the given number of words from the
+// given word list.
+func GenerateWithWordList(numWords int, wordList WordList) ([]string, error) {
+	gen, err := NewGenerator(&GeneratorInput{
+		WordList: wordList,
+	})
+	if err != nil {
+		return nil, err
+	}
+	return gen.Generate(numWords)
+}
+
+// WordAt retrieves the word at the given index from EFF's large wordlist.
+//
+// Deprecated: Use WordList.WordAt instead.
+func WordAt(i int) string {
+	return WordListEffLarge().WordAt(i)
+}
+
+// RollDie rolls a single 6-sided die and returns a value between [1,6].
+//
+// Internally this creates a new Generator with a nil configuration and calls
+// Generator.RollDie.
+func RollDie() (int, error) {
+	gen, err := NewGenerator(nil)
+	if err != nil {
+		return 0, err
+	}
+	return gen.RollDie()
+}
+
+// RollWord rolls and aggregates dice to represent one word in the list. The
+// result is the index of the word in the list.
+//
+// Internally this creates a new Generator with a nil configuration and calls
+// Generator.RollWord.
+func RollWord(d int) (int, error) {
+	gen, err := NewGenerator(nil)
+	if err != nil {
+		return 0, err
+	}
+	return gen.RollWord(d)
+}
+
+// RollDie rolls a single 6-sided die and returns a value between [1,6].
+func (g *Generator) RollDie() (int, error) {
+	r, err := rand.Int(g.randReader, sides)
+	if err != nil {
+		return 0, fmt.Errorf("failed to generate a random number: %w", err)
+	}
+	return int(r.Int64()) + 1, nil
+}
+
+// RollWord rolls and aggregates dice to represent one word in the list. The
+// result is the index of the word in the list.
+func (g *Generator) RollWord(d int) (int, error) {
+	var final int
+
+	for i := d; i > 0; i-- {
+		res, err := g.RollDie()
+		if err != nil {
+			return 0, err
+		}
+
+		final += res * int(math.Pow(10, float64(i-1)))
+	}
+
+	return final, nil
+}

vendor/github.com/sethvargo/go-diceware/diceware/interface.go

@@ -0,0 +1,6 @@
+package diceware
+
+type DicewareGenerator interface {
+	Generate(int) ([]string, error)
+	MustGenerate(int) []string
+}

vendor/github.com/sethvargo/go-diceware/diceware/mock.go

@@ -0,0 +1,38 @@
+package diceware
+
+var _ DicewareGenerator = (*mockGenerator)(nil)
+
+type mockGenerator struct {
+	result []string
+	err    error
+}
+
+// NewMockGenerator creates a new generator that satisfies the DicewareGenerator
+// interface. If an error is provided, the error is returned. If a result if
+// provided, the result is always returned, regardless of what parameters are
+// passed into the Generate or MustGenerate methods.
+//
+// This function is most useful for tests where you want to have predicable
+// results for a transitive resource that depends on go-diceware.
+func NewMockGenerator(result []string, err error) *mockGenerator {
+	return &mockGenerator{
+		result: result,
+		err:    err,
+	}
+}
+
+// Generate returns the mocked result or error.
+func (g *mockGenerator) Generate(int) ([]string, error) {
+	if g.err != nil {
+		return nil, g.err
+	}
+	return g.result, nil
+}
+
+// MustGenerate returns the mocked result or panics if an error was given.
+func (g *mockGenerator) MustGenerate(int) []string {
+	if g.err != nil {
+		panic(g.err)
+	}
+	return g.result
+}

vendor/github.com/sethvargo/go-diceware/diceware/word_list.go

@@ -0,0 +1,42 @@
+package diceware
+
+// WordList is an interface that must be implemented to be considered a word
+// list for use in the diceware algorithm. This interface can be implemented by
+// other libraries.
+type WordList interface {
+	// Digits is the number of digits for indexes in the word list. This
+	// determines the number of dice rolls.
+	Digits() int
+
+	// WordAt returns the word at the given integer in the word list.
+	WordAt(int) string
+}
+
+// WordListNumWordser is an auxiliary interface that returns the number of words
+// in the list. This is a separate interface for backwards compatibility.
+type WordListNumWordser interface {
+	// NumWords returns the total number of words in the list.
+	NumWords() int
+}
+
+var (
+	_ WordList           = (*wordListInternal)(nil)
+	_ WordListNumWordser = (*wordListInternal)(nil)
+)
+
+type wordListInternal struct {
+	digits int
+	words  map[int]string
+}
+
+func (w *wordListInternal) Digits() int {
+	return w.digits
+}
+
+func (w *wordListInternal) WordAt(i int) string {
+	return w.words[i]
+}
+
+func (w *wordListInternal) NumWords() int {
+	return len(w.words)
+}