Make Stream_Cipher::set_iv() pure virtual

It provided a default implementation that only checked
that the length was correct, but ignored the actual data
and did not notify the caller, which seemed like a
rather odd behaviour.

The only implementation that used this default implementation,
RC4, now throws an exception.

2 files changed, 8 insertions, 0 deletions

diff --git a/src/lib/stream/rc4/rc4.cpp b/src/lib/stream/rc4/rc4.cpp
index a4dea9e2b..e5ea2e2b8 100644
--- a/src/lib/stream/rc4/rc4.cpp
+++ b/src/lib/stream/rc4/rc4.cpp
@@ -6,6 +6,7 @@
 */
 
 #include <botan/rc4.h>
+#include <botan/exceptn.h>
 
 namespace Botan {
 
@@ -35,6 +36,11 @@ void RC4::cipher(const byte in[], byte out[], size_t length)
    m_position += length;
    }
 
+void RC4::set_iv(const byte*, size_t)
+   {
+   throw Exception("RC4 does not support an IV");
+   }
+
 /*
 * Generate cipher stream
 */
diff --git a/src/lib/stream/rc4/rc4.h b/src/lib/stream/rc4/rc4.h
index 88798fae6..82dd6097b 100644
--- a/src/lib/stream/rc4/rc4.h
+++ b/src/lib/stream/rc4/rc4.h
@@ -21,6 +21,8 @@ class BOTAN_DLL RC4 final : public StreamCipher
    public:
       void cipher(const byte in[], byte out[], size_t length) override;
 
+      void set_iv(const byte iv[], size_t iv_len) override;
+
       void clear() override;
       std::string name() const override;