Merge pull request #2 from brianasapp/bd/crypto-rand

make cryptographically secure randoms the default

README.md

@@ -1,7 +1,5 @@
 # sputter
 
-_WARNING: I AM NOT CRYPTO FRIENDLY_
-
 POSIX basic regular expressions to psuedo random string generator, just for fun :)
 
 ### Usage
@@ -31,6 +29,8 @@ WordWord
 Њѯѹկ¢↔≡♲
 ```
 
+_For cryptographically insecure usage, use the `GenInsecure` function in place of `Gen`_
+
 
 
 ### Supported Operations

sputter.go

@@ -2,7 +2,9 @@ package sputter
 
 import (
 	"bytes"
+	crypto "crypto/rand"
 	"fmt"
+	"math/big"
 	"math/rand"
 	"regexp/syntax"
 	"time"
@@ -11,15 +13,33 @@ import (
 
 const (
 	repetitionMax = 100
+	maxUint64     = ^uint64(0)
+	maxInt64      = int64(maxUint64 >> 1)
 )
 
+func init() {
+	rand.Seed(time.Now().UTC().UnixNano())
+}
+
 // Gen takes a regular expression and attempts
 //  to generate a pseudo-randomized string that
 //  matches the input expression.
 func Gen(exp string) (string, error) {
-	// setup random package
-	rand.Seed(time.Now().UTC().UnixNano())
+	// cryptographically seed random package
+	bigSeed, err := crypto.Int(crypto.Reader, big.NewInt(maxInt64))
+	if err != nil {
+		return "", err
+	}
+	rand.Seed(bigSeed.Int64())
+
+	r, err := syntax.Parse(exp, 0)
+	if err != nil {
+		return "", err
+	}
+	return sput(r)
+}
 
+func GenInsecure(exp string) (string, error) {
 	r, err := syntax.Parse(exp, 0)
 	if err != nil {
 		return "", err

sputter_test.go

@@ -62,6 +62,7 @@ func TestEndLine(t *testing.T) {
 }
 
 func testSputHundredEmoji(t *testing.T, exp string) {
+	// test cryptographically secure function 100 times
 	for i := 0; i < 100; i++ {
 		s, err := Gen(exp)
 		if err != nil {
@@ -77,4 +78,21 @@ func testSputHundredEmoji(t *testing.T, exp string) {
 			t.Error(err)
 		}
 	}
+
+	// do same for cryptographically insecure function
+	for i := 0; i < 100; i++ {
+		s, err := GenInsecure(exp)
+		if err != nil {
+			t.Error(`error from Gen:`, err)
+		}
+
+		match, err := regexp.Match(exp, []byte(s))
+		if !match {
+			t.Errorf(`output string "%s" does not match expression "%s"`, s, exp)
+		}
+
+		if err != nil {
+			t.Error(err)
+		}
+	}
 }