diff --git a/pdf/core/security/crypt/filter_aesv2.go b/pdf/core/security/crypt/filter_aesv2.go
index 301c202a..06cb566a 100644
--- a/pdf/core/security/crypt/filter_aesv2.go
+++ b/pdf/core/security/crypt/filter_aesv2.go
@@ -5,7 +5,11 @@
 
 package crypt
 
-import "fmt"
+import (
+	"fmt"
+
+	"github.com/unidoc/unidoc/common"
+)
 
 func init() {
 	registerFilter("AESV2", newFilterAESV2)
@@ -21,6 +25,10 @@ func NewFilterAESV2() Filter {
 }
 
 func newFilterAESV2(d FilterDict) (Filter, error) {
+	if d.Length == 128 {
+		common.Log.Debug("AESV2 crypt filter length appears to be in bits rather than bytes - assuming bits (%d)", d.Length)
+		d.Length /= 8
+	}
 	if d.Length != 0 && d.Length != 16 {
 		return nil, fmt.Errorf("invalid AESV2 crypt filter length (%d)", d.Length)
 	}
diff --git a/pdf/core/security/crypt/filter_aesv3.go b/pdf/core/security/crypt/filter_aesv3.go
index ee399596..e35e0e28 100644
--- a/pdf/core/security/crypt/filter_aesv3.go
+++ b/pdf/core/security/crypt/filter_aesv3.go
@@ -29,6 +29,10 @@ func NewFilterAESV3() Filter {
 }
 
 func newFilterAESV3(d FilterDict) (Filter, error) {
+	if d.Length == 256 {
+		common.Log.Debug("AESV3 crypt filter length appears to be in bits rather than bytes - assuming bits (%d)", d.Length)
+		d.Length /= 8
+	}
 	if d.Length != 0 && d.Length != 32 {
 		return nil, fmt.Errorf("invalid AESV3 crypt filter length (%d)", d.Length)
 	}