Update entropy noise reduction

Instead of reducing noise by default, there's a new flag called
`--noise-reduction` to enable that.

README.md

@@ -63,30 +63,31 @@ Usage:
   gitleaks [OPTIONS]
 
 Application Options:
-  -r, --repo=          Repo url to audit
-      --github-user=   Github user to audit
-      --github-org=    Github organization to audit
-      --github-url=    GitHub API Base URL, use for GitHub Enterprise. Example: https://github.example.com/api/v3/ (default: https://api.github.com/)
-      --github-pr=     Github PR url to audit. This does not clone the repo. GITHUB_TOKEN must be set
-      --gitlab-user=   GitLab user ID to audit
-      --gitlab-org=    GitLab group ID to audit
-  -c, --commit=        sha of commit to stop at
-      --depth=         maximum commit depth
-      --repo-path=     Path to repo
-      --owner-path=    Path to owner directory (repos discovered)
-      --threads=       Maximum number of threads gitleaks spawns
-      --disk           Clones repo(s) to disk
-      --single-search= single regular expression to search for
-      --config=        path to gitleaks config
-      --ssh-key=       path to ssh key
-      --exclude-forks  exclude forks for organization/user audits
-  -e, --entropy=       Include entropy checks during audit. Entropy scale: 0.0(no entropy) - 8.0(max entropy)
-  -l, --log=           log level
-  -v, --verbose        Show verbose output from gitleaks audit
-      --report=        path to write report file
-      --redact         redact secrets from log messages and report
-      --version        version number
-      --sample-config  prints a sample config file
+  -r, --repo=           Repo url to audit
+      --github-user=    Github user to audit
+      --github-org=     Github organization to audit
+      --github-url=     GitHub API Base URL, use for GitHub Enterprise. Example: https://github.example.com/api/v3/ (default: https://api.github.com/)
+      --github-pr=      Github PR url to audit. This does not clone the repo. GITHUB_TOKEN must be set
+      --gitlab-user=    GitLab user ID to audit
+      --gitlab-org=     GitLab group ID to audit
+  -c, --commit=         sha of commit to stop at
+      --depth=          maximum commit depth
+      --repo-path=      Path to repo
+      --owner-path=     Path to owner directory (repos discovered)
+      --threads=        Maximum number of threads gitleaks spawns
+      --disk            Clones repo(s) to disk
+      --single-search=  single regular expression to search for
+      --config=         path to gitleaks config
+      --ssh-key=        path to ssh key
+      --exclude-forks   exclude forks for organization/user audits
+  -e, --entropy=        Include entropy checks during audit. Entropy scale: 0.0(no entropy) - 8.0(max entropy)
+      --noise-reduction Reduce the number of finds when entropy checks are enabled
+  -l, --log=            log level
+  -v, --verbose         Show verbose output from gitleaks audit
+      --report=         path to write report file
+      --redact          redact secrets from log messages and report
+      --version         version number
+      --sample-config   prints a sample config file
 
 Help Options:
   -h, --help           Show this help message

gitleaks_test.go

@@ -590,6 +590,15 @@ func TestAuditRepo(t *testing.T) {
 			testOpts: Options{
 				Entropy: 4.7,
 			},
+			numLeaks: 6,
+		},
+		{
+			repo:        leaksRepo,
+			description: "leaks present with entropy",
+			testOpts: Options{
+				Entropy:        4.7,
+				NoiseReduction: true,
+			},
 			numLeaks: 2,
 		},
 		{
@@ -611,6 +620,15 @@ func TestAuditRepo(t *testing.T) {
 		{
 			repo:        leaksRepo,
 			description: "toml entropy range",
+			numLeaks:    298,
+			configPath:  path.Join(configsDir, "entropy"),
+		},
+		{
+			repo: leaksRepo,
+			testOpts: Options{
+				NoiseReduction: true,
+			},
+			description: "toml entropy range",
 			numLeaks:    58,
 			configPath:  path.Join(configsDir, "entropy"),
 		},

main.go

@@ -77,13 +77,14 @@ type Options struct {
 	OwnerPath string `long:"owner-path" description:"Path to owner directory (repos discovered)"`
 
 	// Process options
-	Threads      int     `long:"threads" description:"Maximum number of threads gitleaks spawns"`
-	Disk         bool    `long:"disk" description:"Clones repo(s) to disk"`
-	SingleSearch string  `long:"single-search" description:"single regular expression to search for"`
-	ConfigPath   string  `long:"config" description:"path to gitleaks config"`
-	SSHKey       string  `long:"ssh-key" description:"path to ssh key"`
-	ExcludeForks bool    `long:"exclude-forks" description:"exclude forks for organization/user audits"`
-	Entropy      float64 `long:"entropy" short:"e" description:"Include entropy checks during audit. Entropy scale: 0.0(no entropy) - 8.0(max entropy)"`
+	Threads        int     `long:"threads" description:"Maximum number of threads gitleaks spawns"`
+	Disk           bool    `long:"disk" description:"Clones repo(s) to disk"`
+	SingleSearch   string  `long:"single-search" description:"single regular expression to search for"`
+	ConfigPath     string  `long:"config" description:"path to gitleaks config"`
+	SSHKey         string  `long:"ssh-key" description:"path to ssh key"`
+	ExcludeForks   bool    `long:"exclude-forks" description:"exclude forks for organization/user audits"`
+	Entropy        float64 `long:"entropy" short:"e" description:"Include entropy checks during audit. Entropy scale: 0.0(no entropy) - 8.0(max entropy)"`
+	NoiseReduction bool    `long:"noise-reduction" description:"Reduce the number of finds when entropy checks are enabled"`
 	// TODO: IncludeMessages  string `long:"messages" description:"include commit messages in audit"`
 
 	// Output options
@@ -725,6 +726,10 @@ func entropyIsHighEnough(entropy float64) bool {
 }
 
 func highEntropyLineIsALeak(line string) bool {
+	if !opts.NoiseReduction {
+		return true
+	}
+
 	for _, re := range entropyRegexes {
 		if re.FindString(line) != "" {
 			return true