maybe fix out of bounds (#843)

config/config.go

@@ -4,6 +4,7 @@ import (
 	_ "embed"
 	"fmt"
 	"regexp"
+	"strings"
 )
 
 //go:embed gitleaks.toml
@@ -64,7 +65,9 @@ func (vc *ViperConfig) Translate() (Config, error) {
 		if r.Keywords == nil {
 			r.Keywords = []string{}
 		} else {
-			keywords = append(keywords, r.Keywords...)
+			for _, k := range r.Keywords {
+				keywords = append(keywords, strings.ToLower(k))
+			}
 		}
 
 		if r.Tags == nil {

detect/detect.go

@@ -393,9 +393,10 @@ func (d *Detector) Detect(fragment Fragment) []report.Finding {
 	fragment.newlineIndices = regexp.MustCompile("\n").FindAllStringIndex(fragment.Raw, -1)
 
 	// build keyword map for prefiltering rules
-	matches := d.prefilter.FindAll(strings.ToLower(fragment.Raw))
+	normalizedRaw := strings.ToLower(fragment.Raw)
+	matches := d.prefilter.FindAll(normalizedRaw)
 	for _, m := range matches {
-		fragment.keywords[strings.ToLower(fragment.Raw[m.Start():m.End()])] = true
+		fragment.keywords[normalizedRaw[m.Start():m.End()]] = true
 	}
 
 	for _, rule := range d.Config.Rules {