Add binary mode for secret generation

This commit updates the password generator to now include a binary mode. This mode produces a 256 bits long fully binary secret which can be used for AES-256 encryption. New flags `-bh` (print hex representation) and `-bn` (new line after secret) have been added for this mode. The version has also been updated to 1.0.1 recognizing this new addition.

README.md

@@ -49,6 +49,14 @@ vEbErlaFryaNgyex (vE-bEr-la-Fry-aN-gy-ex)
 We generated a 15-character long pronounceable phrase with syllables output, for easy
 use in e. g. a phone verification process.
 
+### Cryptographic key for encryption
+```shell
+$ apg -a 3 -f 32 -bh
+```
+We generated a 32 bytes/256 bits long fully binary secret that can be used i. e. as
+encryption key for a AES-256 symmetric encryption. The output is represented in 
+hexadecimal format.
+
 ## Installation
 
 ### Docker
@@ -327,6 +335,24 @@ Heads
 Heads
 ```
 
+### Binary mode
+Since v1.0.1 apg-go has a new algorithm for binary secrets. This is a very basic mode that will ignore
+most of the available options, as it will only generate binary secrets with full 256 bits of randomness.
+The only available options for this mode are: `-f` to set the length of the returned secret in bytes, 
+`-bh` to tell apg-go to output the generated secret in hexadecial representation and `-bn` to instruct
+apg-go to return a newline after the generated secret. Any other option available in the other modes
+will be ignored.
+
+This mode can be useful for example if you need to generate a AES-256 encryption key. Since 32 bytes is
+the default length for the secret generation in this mode, you can simply generate a secret key with 
+the following command:
+```shell
+$ apg -a 3 -bh
+a1cdab8db365af3d70828b1fe43b7896190c157ad3f1ae2a0a1d52ec1628c6b5
+```
+*For ease for readability we used the `-bh` flag, to instruct apg-go to output the secret in its
+hexadecimal representation*
+
 ### Minimum required characters
 Even though in apg-go you can select what kind of characters are used for the password generation, it is
 not guaranteed, that if you request a password with a numeric value, that the generated password will 
@@ -376,6 +402,9 @@ _apg-go_ replicates most of the parameters of the original c-apg. Some parameter
   - `0`: Pronouncable password generation (Koremutake syllables)
   - `1`: Random password generation according to password modes/flags
   - `2`: Coinflip (returns heads or tails)
+  - `3`: Binary mode (returns a secret with 256 bits of randomness)
+- `-bh`: When set, will print the generated secret in its hex representation (Default: off)
+- `-bn`: When set, will return a new line character after the generated secret (Default: off)
 - `-m <length>`: The minimum length of the password to be generated (Default: 12)
 - `-x <length>`: The maximum length of the password to be generated (Default: 20)
 - `-f <length>`: Fixed length of the password to be generated (Ignores -m and -x)

algo.go

@@ -18,6 +18,9 @@ const (
 	// AlgoCoinFlip represents a very simple coinflip algorithm returning "heads"
 	// or "tails"
 	AlgoCoinFlip
+	// AlgoBinary represents a full binary randomness mode with up to 256 bits
+	// of randomness
+	AlgoBinary
 	// AlgoUnsupported represents an unsupported algorithm
 	AlgoUnsupported
 )
@@ -32,6 +35,8 @@ func IntToAlgo(a int) Algorithm {
 		return AlgoRandom
 	case 2:
 		return AlgoCoinFlip
+	case 3:
+		return AlgoBinary
 	default:
 		return AlgoUnsupported
 	}

algo_test.go

@@ -4,7 +4,9 @@
 
 package apg
 
-import "testing"
+import (
+	"testing"
+)
 
 func TestIntToAlgo(t *testing.T) {
 	tt := []struct {
@@ -15,7 +17,8 @@ func TestIntToAlgo(t *testing.T) {
 		{"AlgoPronounceable", 0, AlgoPronounceable},
 		{"AlgoRandom", 1, AlgoRandom},
 		{"AlgoCoinflip", 2, AlgoCoinFlip},
-		{"AlgoUnsupported", 3, AlgoUnsupported},
+		{"AlgoBinary", 3, AlgoBinary},
+		{"AlgoUnsupported", 4, AlgoUnsupported},
 	}
 	for _, tc := range tt {
 		t.Run(tc.name, func(t *testing.T) {

apg.go

@@ -5,7 +5,7 @@
 package apg
 
 // VERSION represents the version string
-const VERSION = "1.0.0"
+const VERSION = "1.0.1"
 
 // Generator is the password generator type of the APG package
 type Generator struct {

cmd/apg/apg.go

@@ -31,6 +31,8 @@ func main() {
 	var modeString string
 	var complexPass, humanReadable, lowerCase, numeric, special, showVer, upperCase bool
 	flag.IntVar(&algorithm, "a", 1, "")
+	flag.BoolVar(&config.BinaryHexMode, "bh", false, "")
+	flag.BoolVar(&config.BinaryNewline, "bn", false, "")
 	flag.BoolVar(&complexPass, "C", false, "")
 	flag.StringVar(&config.ExcludeChars, "E", "", "")
 	flag.Int64Var(&config.FixedLength, "f", 0, "")
@@ -144,6 +146,23 @@ func configOldStyle(config *apg.Config, humanReadable, lowerCase, upperCase,
 
 func generate(config *apg.Config) {
 	generator := apg.New(config)
+
+	// In binary mode we only generate a single secret
+	if config.Algorithm == apg.AlgoBinary {
+		password, err := generator.Generate()
+		if err != nil {
+			_, _ = fmt.Fprintf(os.Stderr, "failed to generate password: %s\n", err)
+			os.Exit(1)
+		}
+		if config.BinaryNewline {
+			fmt.Println(password)
+			return
+		}
+		fmt.Print(password)
+		return
+	}
+
+	// For any other mode we cycle through the amount of passwords to be generated
 	for i := int64(0); i < config.NumberPass; i++ {
 		password, err := generator.Generate()
 		if err != nil {
@@ -197,12 +216,17 @@ Flags:
                           - 0: pronounceable password generation (koremutake syllables)
                           - 1: random password generation according to password modes/flags
                           - 2: coinflip (returns heads or tails)
+                          - 3: full binary mode (generates simple 256 bit randomness)
+    -bh                  When set, will print the generated secret in its hex representation (Default: off)
+    -bn                  When set, will return a new line character after the generated secret (Default: off)
+                          - Note: The -bX options only apply to binary mode (Algo: 3)
     -m LENGTH            Minimum length of the password to be generated (Default: 12)
     -x LENGTH            Maximum length of the password to be generated (Default: 20)
     -f LENGTH            Fixed length of the password to be generated (Ignores -m and -x)
                           - Note: Due to the way the pronounceable password algorithm works,
 	                        this setting might not always apply
     -n NUMBER            Amount of password to be generated (Default: 6)
+                          - Note: Does not apply to binary mode (Algo: 3)
     -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

config.go

@@ -10,6 +10,8 @@ const (
 	DefaultMinLength int64 = 12
 	// DefaultMaxLength reflects the default maximum length of a generated password
 	DefaultMaxLength int64 = 20
+	// DefaultBinarySize is the default byte size for generating binary random bytes
+	DefaultBinarySize int64 = 32
 	// DefaultMode sets the default character set mode bitmask to a combination of
 	// lower- and upper-case characters as well as numbers
 	DefaultMode ModeMask = ModeLowerCase | ModeNumeric | ModeUpperCase
@@ -21,6 +23,11 @@ const (
 type Config struct {
 	// Algorithm sets the Algorithm used for the password generation
 	Algorithm Algorithm
+	// BinaryHexMode if set will output the hex representation of the generated
+	// binary random string
+	BinaryHexMode bool
+	// BinaryNewline if set will print out a new line in AlgoBinary mode
+	BinaryNewline bool
 	// CheckHIBP sets a flag if the generated password has to be checked
 	// against the HIBP pwned password database
 	CheckHIBP bool
@@ -88,6 +95,13 @@ func WithAlgorithm(algo Algorithm) Option {
 	}
 }
 
+// WithBinaryHexMode sets the hex mode for the AlgoBinary
+func WithBinaryHexMode() Option {
+	return func(config *Config) {
+		config.BinaryHexMode = true
+	}
+}
+
 // WithExcludeChars sets a list of characters to be excluded in the generated
 // passwords
 func WithExcludeChars(chars string) Option {

config_test.go

@@ -46,7 +46,8 @@ func TestWithAlgorithm(t *testing.T) {
 		{"Pronounceable passwords", AlgoPronounceable, 0},
 		{"Random passwords", AlgoRandom, 1},
 		{"Coinflip", AlgoCoinFlip, 2},
-		{"Unsupported", AlgoUnsupported, 3},
+		{"Binary", AlgoBinary, 3},
+		{"Unsupported", AlgoUnsupported, 4},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -67,6 +68,18 @@ func TestWithAlgorithm(t *testing.T) {
 	}
 }
 
+func TestWithBinaryHexMode(t *testing.T) {
+	c := NewConfig(WithBinaryHexMode())
+	if c == nil {
+		t.Errorf("NewConfig(WithBinaryHexMode()) failed, expected config pointer but got nil")
+		return
+	}
+	if !c.BinaryHexMode {
+		t.Errorf("NewConfig(WithBinaryHexMode()) failed, expected chars: %t, got: %t",
+			true, c.BinaryHexMode)
+	}
+}
+
 func TestWithExcludeChars(t *testing.T) {
 	e := "abcdefg"
 	c := NewConfig(WithExcludeChars(e))

random.go

@@ -57,10 +57,13 @@ func (g *Generator) Generate() (string, error) {
 		return g.generateCoinFlip()
 	case AlgoRandom:
 		return g.generateRandom()
+	case AlgoBinary:
+		return g.generateBinary()
 	case AlgoUnsupported:
 		return "", fmt.Errorf("unsupported algorithm")
+	default:
+		return "", fmt.Errorf("unsupported algorithm")
 	}
-	return "", nil
 }
 
 // GetCharRangeFromConfig checks the Mode from the Config and returns a
@@ -315,8 +318,26 @@ func (g *Generator) generatePronounceable() (string, error) {
 	return password, nil
 }
 
+// generateBinary is executed when Generate() is called with Algorithm set
+// to AlgoBinary
+func (g *Generator) generateBinary() (string, error) {
+	var length int64 = DefaultBinarySize
+	if g.config.FixedLength > 0 {
+		length = g.config.FixedLength
+	}
+	randBytes := make([]byte, length)
+	_, err := rand.Read(randBytes)
+	if err != nil {
+		return "", fmt.Errorf("failed to generate random bytes: %w", err)
+	}
+	if g.config.BinaryHexMode {
+		return fmt.Sprintf("%x", randBytes), nil
+	}
+	return string(randBytes), nil
+}
+
 // generateRandom is executed when Generate() is called with Algorithm set
-// to AlgoRandmom
+// to AlgoRandom
 func (g *Generator) generateRandom() (string, error) {
 	length, err := g.GetPasswordLength()
 	if err != nil {

random_test.go

@@ -471,6 +471,10 @@ func TestGenerate(t *testing.T) {
 			name:      "Random",
 			algorithm: AlgoRandom,
 		},
+		{
+			name:      "Binary",
+			algorithm: AlgoBinary,
+		},
 		{
 			name:        "Unsupported",
 			algorithm:   AlgoUnsupported,
@@ -530,3 +534,38 @@ func BenchmarkGenerator_RandomString(b *testing.B) {
 		}
 	}
 }
+
+func TestGenerator_generateBinary(t *testing.T) {
+	tests := []struct {
+		name    string
+		config  *Config
+		wantErr bool
+	}{
+		{
+			name:    "Positive Case - Binary in Hex",
+			config:  &Config{FixedLength: 10, BinaryHexMode: true},
+			wantErr: false,
+		},
+		{
+			name:    "Negative Case - Insufficient length",
+			config:  &Config{FixedLength: -1, BinaryHexMode: false},
+			wantErr: false,
+		},
+		{
+			name:    "Positive Case - Binary without Hex",
+			config:  &Config{FixedLength: 10, BinaryHexMode: false},
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := &Generator{config: tt.config}
+			_, err := g.generateBinary()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Generator.generateBinary() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+		})
+	}
+}