Remove copypasta dependency

go.mod

@@ -19,7 +19,6 @@ require (
 	github.com/gorilla/mux v1.7.3
 	github.com/gorilla/websocket v1.4.0 // indirect
 	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0
-	github.com/gtank/cryptopasta v0.0.0-20170601214702-1f550f6f2f69
 	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
 	github.com/kylelemons/godebug v1.1.0
 	github.com/lib/pq v1.3.0

go.sum

@@ -149,8 +149,6 @@ github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 h1:Ovs26xHkKqVztRpIrF/92Bcuy
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.5 h1:UImYN5qQ8tuGpGE16ZmjvcTtTw24zw1QAp/SlnNrZhI=
 github.com/grpc-ecosystem/grpc-gateway v1.9.5/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
-github.com/gtank/cryptopasta v0.0.0-20170601214702-1f550f6f2f69 h1:7xsUJsB2NrdcttQPa7JLEaGzvdbk7KvfrjgHZXOQRo0=
-github.com/gtank/cryptopasta v0.0.0-20170601214702-1f550f6f2f69/go.mod h1:YLEMZOtU+AZ7dhN9T/IpGhXVGly2bvkJQ+zxj3WeVQo=
 github.com/hashicorp/errwrap v0.0.0-20141028054710-7554cd9344ce/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/go-multierror v0.0.0-20161216184304-ed905158d874/go.mod h1:JMRHfdO9jKNzS/+BTlxCjKNQHg/jZAft8U7LloJvN7I=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=

storage/kubernetes/client.go

@@ -23,7 +23,6 @@ import (
 	"time"
 
 	"github.com/ghodss/yaml"
-	"github.com/gtank/cryptopasta"
 	"golang.org/x/net/http2"
 
 	"github.com/dexidp/dex/pkg/log"
@@ -253,8 +252,23 @@ func (cli *client) put(resource, name string, v interface{}) error {
 	return checkHTTPErr(resp, http.StatusOK)
 }
 
+// Copied from https://github.com/gtank/cryptopasta
+func defaultTLSConfig() *tls.Config {
+	return &tls.Config{
+		// Avoids most of the memorably-named TLS attacks
+		MinVersion: tls.VersionTLS12,
+		// Causes servers to use Go's default ciphersuite preferences,
+		// which are tuned to avoid attacks. Does nothing on clients.
+		PreferServerCipherSuites: true,
+		// Only use curves which have constant-time implementations
+		CurvePreferences: []tls.CurveID{
+			tls.CurveP256,
+		},
+	}
+}
+
 func newClient(cluster k8sapi.Cluster, user k8sapi.AuthInfo, namespace string, logger log.Logger) (*client, error) {
-	tlsConfig := cryptopasta.DefaultTLSConfig()
+	tlsConfig := defaultTLSConfig()
 	data := func(b string, file string) ([]byte, error) {
 		if b != "" {
 			return base64.StdEncoding.DecodeString(b)