fix(dex): store raw bcrypt hash in Password CR, not base64-encoded

The original NOTE claimed Dex's kubernetes storage types Hash as []byte,
requiring the bcrypt string to be base64-encoded before storage. This was
wrong: Dex v2.41 stores and compares the hash field as a plain string. The
base64-encoding caused every invite login to fail with 'Invalid credentials'
because Dex passed the base64 bytes (starting with 'J' not '$') directly to
bcrypt. Static passwords in the configmap always used raw bcrypt strings and
worked fine — confirming the dynamic CR encoding was the bug.

internal/adapters/dex/dex.go

@@ -17,7 +17,6 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -98,11 +97,12 @@ func newClient(server, token string, hc *http.Client) *PasswordClient {
 	return &PasswordClient{server: server, token: token, http: hc}
 }
 
-// password is the wire form of a Dex Password CR. NOTE: Dex's kubernetes storage
-// types the hash as []byte, which Kubernetes JSON-marshals as base64. So the
-// `hash` field must carry the base64 encoding of the bcrypt string, NOT the raw
-// bcrypt string — store the raw string and Dex's base64-decode on login yields
-// garbage and every login fails. CreatePassword does that encoding.
+// password is the wire form of a Dex Password CR. The hash field is a plain
+// bcrypt string (e.g. "$2a$12$..."). Dex v2.41+ stores and compares it as-is —
+// it does NOT base64-decode the field. Earlier code base64-encoded the hash
+// based on a misread of Dex's internal []byte type; that caused every dynamic
+// invite login to fail with "Invalid credentials" while static passwords (set as
+// plain strings in the configmap) worked fine.
 type password struct {
 	APIVersion string            `json:"apiVersion"`
 	Kind       string            `json:"kind"`
@@ -123,10 +123,9 @@ func (c *PasswordClient) CreatePassword(ctx context.Context, email, bcryptHash,
 		Kind:       "Password",
 		Metadata:   map[string]string{"name": passwordName(email), "namespace": "auth"},
 		Email:      email,
-		// base64 of the bcrypt string — see the password type's NOTE.
-		Hash:     base64.StdEncoding.EncodeToString([]byte(bcryptHash)),
-		Username: email,
-		UserID:   userID,
+		Hash:       bcryptHash, // raw bcrypt string — Dex compares it directly
+		Username:   email,
+		UserID:     userID,
 	})
 	if err != nil {
 		return fmt.Errorf("dex: marshal password: %w", err)

internal/adapters/dex/dex_test.go

@@ -2,7 +2,6 @@ package dex
 
 import (
 	"context"
-	"encoding/base64"
 	"encoding/json"
 	"io"
 	"net/http"
@@ -46,10 +45,8 @@ func TestCreatePasswordSuccess(t *testing.T) {
 	require.Equal(t, "new-dot-user-at-example-dot-com", gotBody.Metadata["name"])
 	require.Equal(t, "auth", gotBody.Metadata["namespace"])
 
-	// The hash is the BASE64 of the bcrypt string (Dex stores hash as []byte).
-	decoded, err := base64.StdEncoding.DecodeString(gotBody.Hash)
-	require.NoError(t, err)
-	require.Equal(t, "$2a$12$abcdefghijklmnopqrstuv", string(decoded))
+	// Hash is stored as the raw bcrypt string — Dex compares it directly.
+	require.Equal(t, "$2a$12$abcdefghijklmnopqrstuv", gotBody.Hash)
 }
 
 func TestCreatePasswordConflict(t *testing.T) {