Implement owner setup and browser authentication sessions

internal/adapters/authn/credentials.go

@@ -0,0 +1,46 @@
+package authn
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base32"
+	"encoding/base64"
+	"fmt"
+	"strings"
+	"time"
+
+	"drive.local/drivev2/internal/application"
+)
+
+type CredentialGenerator struct{}
+
+func (CredentialGenerator) NewCredential() (application.GeneratedCredential, error) {
+	secret := make([]byte, 32)
+	if _, err := rand.Read(secret); err != nil {
+		return application.GeneratedCredential{}, fmt.Errorf("generate credential: %w", err)
+	}
+	plaintext := base64.RawURLEncoding.EncodeToString(secret)
+	digest := sha256.Sum256([]byte(plaintext))
+	return application.GeneratedCredential{Plaintext: plaintext, Digest: digest[:]}, nil
+}
+
+func (CredentialGenerator) NewRecoveryCodes(count int) ([]application.GeneratedCredential, error) {
+	codes := make([]application.GeneratedCredential, 0, count)
+	for range count {
+		raw := make([]byte, 12)
+		if _, err := rand.Read(raw); err != nil {
+			return nil, fmt.Errorf("generate recovery code: %w", err)
+		}
+		encoded := base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(raw)
+		plaintext := strings.Join([]string{encoded[0:5], encoded[5:10], encoded[10:15], encoded[15:20]}, "-")
+		digest := sha256.Sum256([]byte(plaintext))
+		codes = append(codes, application.GeneratedCredential{Plaintext: plaintext, Digest: digest[:]})
+	}
+	return codes, nil
+}
+
+type SystemClock struct{}
+
+func (SystemClock) Now() time.Time {
+	return time.Now()
+}