1 files changed, 31 insertions, 0 deletions
diff --git a/pkg/scrypto/pkcs5.go b/pkg/scrypto/pkcs5.go
new file mode 100644
index 0000000..b41c564
--- /dev/null
+++ b/pkg/scrypto/pkcs5.go
@@ -0,0 +1,31 @@
+package scrypto
+
+import (
+	"bytes"
+	"fmt"
+)
+
+func PadPKCS5(data []byte, blockSize int) []byte {
+	paddingSize := blockSize - len(data)%blockSize
+	padding := bytes.Repeat([]byte{byte(paddingSize)}, paddingSize)
+
+	return append(data, padding...)
+}
+
+func UnpadPKCS5(data []byte, blockSize int) ([]byte, error) {
+	dataSize := len(data)
+	if dataSize%blockSize != 0 {
+		return nil, fmt.Errorf("truncated data")
+	}
+
+	if len(data) == 0 {
+		return data, nil
+	} else {
+		paddingSize := int(data[dataSize-1])
+		if paddingSize > dataSize || paddingSize > blockSize {
+			return nil, fmt.Errorf("invalid padding size %d", paddingSize)
+		}
+
+		return data[:dataSize-paddingSize], nil
+	}
+}