Adding upstream version 0.28.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tools/security/random.go

@@ -0,0 +1,59 @@
+package security
+
+import (
+	cryptoRand "crypto/rand"
+	"math/big"
+	mathRand "math/rand" // @todo replace with rand/v2?
+)
+
+const defaultRandomAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+
+// RandomString generates a cryptographically random string with the specified length.
+//
+// The generated string matches [A-Za-z0-9]+ and it's transparent to URL-encoding.
+func RandomString(length int) string {
+	return RandomStringWithAlphabet(length, defaultRandomAlphabet)
+}
+
+// RandomStringWithAlphabet generates a cryptographically random string
+// with the specified length and characters set.
+//
+// It panics if for some reason rand.Int returns a non-nil error.
+func RandomStringWithAlphabet(length int, alphabet string) string {
+	b := make([]byte, length)
+	max := big.NewInt(int64(len(alphabet)))
+
+	for i := range b {
+		n, err := cryptoRand.Int(cryptoRand.Reader, max)
+		if err != nil {
+			panic(err)
+		}
+		b[i] = alphabet[n.Int64()]
+	}
+
+	return string(b)
+}
+
+// PseudorandomString generates a pseudorandom string with the specified length.
+//
+// The generated string matches [A-Za-z0-9]+ and it's transparent to URL-encoding.
+//
+// For a cryptographically random string (but a little bit slower) use RandomString instead.
+func PseudorandomString(length int) string {
+	return PseudorandomStringWithAlphabet(length, defaultRandomAlphabet)
+}
+
+// PseudorandomStringWithAlphabet generates a pseudorandom string
+// with the specified length and characters set.
+//
+// For a cryptographically random (but a little bit slower) use RandomStringWithAlphabet instead.
+func PseudorandomStringWithAlphabet(length int, alphabet string) string {
+	b := make([]byte, length)
+	max := len(alphabet)
+
+	for i := range b {
+		b[i] = alphabet[mathRand.Intn(max)]
+	}
+
+	return string(b)
+}