add crypto package

crypto/crypto.go

@@ -0,0 +1,50 @@
+package crypto
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"math/big"
+	"sort"
+	"strings"
+
+	"github.com/lbryio/lbry.go/errors"
+
+	"github.com/btcsuite/btcutil/base58"
+	"golang.org/x/crypto/sha3"
+)
+
+// RandString returns a random alphanumeric string of a given length
+func RandString(length int) string {
+	buf := make([]byte, length)
+	_, err := rand.Reader.Read(buf)
+	if err != nil {
+		panic(errors.Err(err))
+	}
+
+	randStr := base58.Encode(buf)[:length]
+	if len(randStr) < length {
+		panic(errors.Err("Could not create random string that is long enough"))
+	}
+
+	return randStr
+}
+
+// Int returns a uniform random value in [0, max). It panics if max <= 0.
+func RandInt64(max int64) int64 {
+	n, err := rand.Int(rand.Reader, big.NewInt(max))
+	if err != nil {
+		panic(err)
+	}
+	return n.Int64()
+}
+
+// HashStringSlice returns a hex hash of a slice of strings
+func HashStringSlice(data []string) string {
+	return hex.EncodeToString(hashStringSliceRaw(data))
+}
+
+func hashStringSliceRaw(data []string) []byte {
+	sort.Strings(data)
+	hash := sha3.Sum256([]byte(strings.Join(data, "")))
+	return hash[:]
+}