wneessen/apg-go
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#52 and #53: Increase password generation flexibility and error handling

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Added code to check if set minimum password requirements are met after generating a random password. If not, the password generation process is repeated.
This not only adds an extra layer of security but also ensures that all set criteria for the password are met.
Also enhanced error handling in functions that could return a negative integer when asked for a random number.
Changed 'minimum amount of' parameter descriptions in apg.go to avoid confusion.
This commit is contained in:
Winni Neessen 2023-08-06 18:55:47 +02:00
parent 2822f73f56
commit 203da17634
Signed by: wneessen
GPG key ID: 5F3AF39B820C119D
4 changed files with 244 additions and 66 deletions
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44
cmd/apg/apg.go
View file

@ -10,6 +10,13 @@ import (
"github.com/wneessen/apg-go"
)
// MinimumAmountTooHigh is an error message displayed when a minimum amount of
// parameter has been set to a too high value
const MinimumAmountTooHigh = "WARNING: You have selected a minimum amount of characters that is bigger\n" +
"than 50% of the minimum password length to be generated. This can lead\n" +
"to extraordinary calculation times resulting in apg-go never finishing\n" +
"the job. Please consider lowering the value.\n\n"
func main() {
c := apg.NewConfig()
@ -64,6 +71,33 @@ func main() {
c.Mode = apg.ModesFromFlags(ms)
}
// For the "minimum amount of" modes we need to imply at the type
// of character mode is set
if c.MinLowerCase > 0 {
if float64(c.MinLength)/2 < float64(c.MinNumeric) {
_, _ = os.Stderr.WriteString(MinimumAmountTooHigh)
}
c.Mode = apg.MaskSetMode(c.Mode, apg.ModeLowerCase)
}
if c.MinNumeric > 0 {
if float64(c.MinLength)/2 < float64(c.MinLowerCase) {
_, _ = os.Stderr.WriteString(MinimumAmountTooHigh)
}
c.Mode = apg.MaskSetMode(c.Mode, apg.ModeNumeric)
}
if c.MinSpecial > 0 {
if float64(c.MinLength)/2 < float64(c.MinSpecial) {
_, _ = os.Stderr.WriteString(MinimumAmountTooHigh)
}
c.Mode = apg.MaskSetMode(c.Mode, apg.ModeSpecial)
}
if c.MinUpperCase > 0 {
if float64(c.MinLength)/2 < float64(c.MinUpperCase) {
_, _ = os.Stderr.WriteString(MinimumAmountTooHigh)
}
c.Mode = apg.MaskSetMode(c.Mode, apg.ModeUpperCase)
}
// Check if algorithm is supported
c.Algorithm = apg.IntToAlgo(al)
if c.Algorithm == apg.AlgoUnsupported {
@ -106,10 +140,12 @@ Flags:
-E CHARS List of characters to be excluded in the generated password
-M [LUNSHClunshc] New style password flags
- Note: new-style flags have higher priority than any of the old-style flags
-mL NUMBER Minimal amount of lower-case characters (implies -L)
-mN NUMBER Minimal amount of numeric characters (imlies -N)
-mS NUMBER Minimal amount of special characters (imlies -S)
-mU NUMBER Minimal amount of upper-case characters (imlies -U)
-mL NUMBER Minimum amount of lower-case characters (implies -L)
-mN NUMBER Minimum amount of numeric characters (imlies -N)
-mS NUMBER Minimum amount of special characters (imlies -S)
-mU NUMBER Minimum amount of upper-case characters (imlies -U)
- Note: any of the "Minimum amount of" modes may result in
extraordinarily long calculation times
-C Enable complex password mode (implies -L -U -N -S and disables -H)
-H Avoid ambiguous characters in passwords (i. e.: 1, l, I, O, 0) (Default: off)
-L Toggle lower-case characters in passwords (Default: on)

4
mode.go
View file

@ -37,8 +37,8 @@ const (
CharRangeAlphaUpperHuman = "ABCDEFGHJKMNPQRSTUVWXYZ"
// CharRangeNumeric represents all numerical characters
CharRangeNumeric = "1234567890"
// CharRangeNumberHuman represents all human-readable numerical characters
CharRangeNumberHuman = "23456789"
// CharRangeNumericHuman represents all human-readable numerical characters
CharRangeNumericHuman = "23456789"
// CharRangeSpecial represents all special characters
CharRangeSpecial = `!\"#$%&'()*+,-./:;<=>?@[\\]^_{|}~`
// CharRangeSpecialHuman represents all human-readable special characters

258
random.go
View file

@ -27,28 +27,54 @@ var (
ErrInvalidCharRange = errors.New("provided character range is not valid or empty")
)
// CoinFlip performs a simple coinflip based on the rand library and returns 1 or 0
func (g *Generator) CoinFlip() int64 {
cf, _ := g.RandNum(2)
return cf
}
// CoinFlipBool performs a simple coinflip based on the rand library and returns true or false
func (g *Generator) CoinFlipBool() bool {
return g.CoinFlip() == 1
}
// Generate generates a password based on all the different config flags and returns
// it as string type. If the generation fails, an error will be thrown
func (g *Generator) Generate() (string, error) {
// Coinflip mode
if g.config.Algorithm == AlgoCoinFlip {
switch g.CoinFlipBool() {
case true:
return "Heads", nil
case false:
return "Tails", nil
}
switch g.config.Algorithm {
case AlgoCoinFlip:
return g.generateCoinFlip()
case AlgoRandom:
return g.generateRandom()
case AlgoUnsupported:
return "", fmt.Errorf("unsupported algorithm")
}
l, err := g.GetPasswordLength()
if err != nil {
return "", fmt.Errorf("failed to calculate password length: %w", err)
}
_ = l
return "", nil
}
// GetPasswordLength returns the password length based on the given config
// parameters
func (g *Generator) GetPasswordLength() (int64, error) {
if g.config.FixedLength > 0 {
return g.config.FixedLength, nil
}
mil := g.config.MinLength
mal := g.config.MaxLength
if mil > mal {
mal = mil
}
diff := mal - mil + 1
ra, err := g.RandNum(diff)
if err != nil {
return 0, err
}
l := mil + ra
if l <= 0 {
return 1, nil
}
return l, nil
}
// RandomBytes returns a byte slice of random bytes with length n that got generated by
// the crypto/rand generator
func (g *Generator) RandomBytes(n int64) ([]byte, error) {
@ -67,10 +93,23 @@ func (g *Generator) RandomBytes(n int64) ([]byte, error) {
return b, nil
}
// RandNum generates a random, non-negative number with given maximum value
func (g *Generator) RandNum(m int64) (int64, error) {
if m < 1 {
return 0, ErrInvalidLength
}
mbi := big.NewInt(m)
rn, err := rand.Int(rand.Reader, mbi)
if err != nil {
return 0, fmt.Errorf("random number generation failed: %w", err)
}
return rn.Int64(), nil
}
// RandomStringFromCharRange returns a random string of length l based of the range of characters given.
// The method makes use of the crypto/random package and therfore is
// cryptographically secure
func (g *Generator) RandomStringFromCharRange(l int, cr string) (string, error) {
func (g *Generator) RandomStringFromCharRange(l int64, cr string) (string, error) {
if l < 1 {
return "", ErrInvalidLength
}
@ -78,7 +117,13 @@ func (g *Generator) RandomStringFromCharRange(l int, cr string) (string, error)
return "", ErrInvalidCharRange
}
rs := strings.Builder{}
rs.Grow(l)
// As long as the length is smaller than the max. int32 value let's grow
// the string builder to the actual size, so we need less allocations
if l <= 2147483647 {
rs.Grow(int(l))
}
crl := len(cr)
rp := make([]byte, 8)
@ -105,49 +150,146 @@ func (g *Generator) RandomStringFromCharRange(l int, cr string) (string, error)
return rs.String(), nil
}
// RandNum generates a random, non-negative number with given maximum value
func (g *Generator) RandNum(m int64) (int64, error) {
if m < 1 {
return 0, ErrInvalidLength
// GetCharRangeFromConfig checks the Mode from the Config and returns a
// list of all possible characters that are supported by these Mode
func (g *Generator) GetCharRangeFromConfig() string {
cr := strings.Builder{}
if MaskHasMode(g.config.Mode, ModeLowerCase) {
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr.WriteString(CharRangeAlphaLowerHuman)
default:
cr.WriteString(CharRangeAlphaLower)
}
}
mbi := big.NewInt(m)
rn, err := rand.Int(rand.Reader, mbi)
if MaskHasMode(g.config.Mode, ModeNumeric) {
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr.WriteString(CharRangeNumericHuman)
default:
cr.WriteString(CharRangeNumeric)
}
}
if MaskHasMode(g.config.Mode, ModeSpecial) {
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr.WriteString(CharRangeSpecialHuman)
default:
cr.WriteString(CharRangeSpecial)
}
}
if MaskHasMode(g.config.Mode, ModeUpperCase) {
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr.WriteString(CharRangeAlphaUpperHuman)
default:
cr.WriteString(CharRangeAlphaUpper)
}
}
return cr.String()
}
func (g *Generator) checkMinimumRequirements(pw string) bool {
ok := true
if g.config.MinLowerCase > 0 {
var cr string
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr = CharRangeAlphaLowerHuman
default:
cr = CharRangeAlphaLower
}
m := 0
for _, c := range cr {
m += strings.Count(pw, string(c))
}
if int64(m) < g.config.MinLowerCase {
ok = false
}
}
if g.config.MinNumeric > 0 {
var cr string
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr = CharRangeNumericHuman
default:
cr = CharRangeNumeric
}
m := 0
for _, c := range cr {
m += strings.Count(pw, string(c))
}
if int64(m) < g.config.MinNumeric {
ok = false
}
}
if g.config.MinSpecial > 0 {
var cr string
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr = CharRangeSpecialHuman
default:
cr = CharRangeSpecial
}
m := 0
for _, c := range cr {
m += strings.Count(pw, string(c))
}
if int64(m) < g.config.MinSpecial {
ok = false
}
}
if g.config.MinUpperCase > 0 {
var cr string
switch MaskHasMode(g.config.Mode, ModeHumanReadable) {
case true:
cr = CharRangeAlphaUpperHuman
default:
cr = CharRangeAlphaUpper
}
m := 0
for _, c := range cr {
m += strings.Count(pw, string(c))
}
if int64(m) < g.config.MinUpperCase {
ok = false
}
}
return ok
}
// generateCoinFlip is executed when Generate() is called with Algorithm set
// to AlgoCoinFlip
func (g *Generator) generateCoinFlip() (string, error) {
switch g.CoinFlipBool() {
case true:
return "Heads", nil
default:
return "Tails", nil
}
}
// generateRandom is executed when Generate() is called with Algorithm set
// to AlgoRandmom
func (g *Generator) generateRandom() (string, error) {
l, err := g.GetPasswordLength()
if err != nil {
return 0, fmt.Errorf("random number generation failed: %w", err)
return "", fmt.Errorf("failed to calculate password length: %w", err)
}
cr := g.GetCharRangeFromConfig()
var pw string
var ok bool
for !ok {
pw, err = g.RandomStringFromCharRange(l, cr)
if err != nil {
return "", err
}
ok = g.checkMinimumRequirements(pw)
}
return rn.Int64(), nil
}
// CoinFlip performs a simple coinflip based on the rand library and returns 1 or 0
func (g *Generator) CoinFlip() int64 {
cf, _ := g.RandNum(2)
return cf
}
// CoinFlipBool performs a simple coinflip based on the rand library and returns true or false
func (g *Generator) CoinFlipBool() bool {
return g.CoinFlip() == 1
}
// GetPasswordLength returns the password length based on the given config
// parameters
func (g *Generator) GetPasswordLength() (int64, error) {
if g.config.FixedLength > 0 {
return g.config.FixedLength, nil
}
mil := g.config.MinLength
mal := g.config.MaxLength
if mil > mal {
mal = mil
}
diff := mal - mil + 1
ra, err := g.RandNum(diff)
if err != nil {
return 0, err
}
l := mil + ra
if l <= 0 {
return 1, nil
}
return l, nil
return pw, nil
}

4
random_test.go
View file

@ -103,7 +103,7 @@ func TestGenerator_RandomBytes(t *testing.T) {
func TestGenerator_RandomString(t *testing.T) {
g := New(NewConfig())
l := 32
var l int64 = 32 * 1024
tt := []struct {
name string
cr string
@ -137,7 +137,7 @@ func TestGenerator_RandomString(t *testing.T) {
if err != nil && !tc.sf {
t.Errorf("RandomStringFromCharRange failed: %s", err)
}
if len(rs) != l && !tc.sf {
if int64(len(rs)) != l && !tc.sf {
t.Errorf("RandomStringFromCharRange failed. Expected length: %d, got: %d", l, len(rs))
}
if strings.ContainsAny(rs, tc.nr) {