Cipher_Mode API improvements

The Cipher_Mode::update API is more general than needed to just
support ciphers (this is due to it previously being an API of
Transform which before 8b85b780515 was Cipher_Mode's base class)

Define a less general interface `process` which either processes the
blocks in-place, producing exactly as much output as there was input,
or (SIV/CCM case) saves the entire message for processing in `finish`.
These two uses cover all current or anticipated cipher modes.

Leaves `update` for compatability with existing callers; all that is
needed is an inline function forwarding to `process`.

Removes the return type from `start` - in all cipher implementations,
this always returned an empty vector.

Adds BOTAN_ARG_CHECK macro; right now BOTAN_ASSERT is being used
for argument checking in some places, which is not right at all.

1 files changed, 5 insertions, 6 deletions

diff --git a/src/lib/modes/stream_mode.h b/src/lib/modes/stream_mode.h
index f5f1aa33a..f59f6d9ba 100644
--- a/src/lib/modes/stream_mode.h
+++ b/src/lib/modes/stream_mode.h
@@ -17,10 +17,10 @@ class BOTAN_DLL Stream_Cipher_Mode : public Cipher_Mode
    public:
       explicit Stream_Cipher_Mode(StreamCipher* cipher) : m_cipher(cipher) {}
 
-      void update(secure_vector<byte>& buf, size_t offset) override
+      size_t process(uint8_t buf[], size_t sz) override
          {
-         if(offset < buf.size())
-            m_cipher->cipher1(&buf[offset], buf.size() - offset);
+         m_cipher->cipher1(buf, sz);
+         return sz;
          }
 
       void finish(secure_vector<byte>& buf, size_t offset) override
@@ -28,7 +28,7 @@ class BOTAN_DLL Stream_Cipher_Mode : public Cipher_Mode
 
       size_t output_length(size_t input_length) const override { return input_length; }
 
-      size_t update_granularity() const override { return 64; /* arbitrary */ }
+      size_t update_granularity() const override { return 1; }
 
       size_t minimum_final_size() const override { return 0; }
 
@@ -44,10 +44,9 @@ class BOTAN_DLL Stream_Cipher_Mode : public Cipher_Mode
       void clear() override { return m_cipher->clear(); }
 
    private:
-      secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override
+      void start_msg(const byte nonce[], size_t nonce_len) override
          {
          m_cipher->set_iv(nonce, nonce_len);
-         return secure_vector<byte>();
          }
 
       void key_schedule(const byte key[], size_t length) override