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, 1 insertions, 1 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index e42f32234..e8df51fec 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -458,7 +458,7 @@ int botan_cipher_start(botan_cipher_t cipher_obj,
    try
       {
       Botan::Cipher_Mode& cipher = safe_get(cipher_obj);
-      BOTAN_ASSERT(cipher.start(nonce, nonce_len).empty(), "Ciphers have no prefix");
+      cipher.start(nonce, nonce_len);
       cipher_obj->m_buf.reserve(cipher.update_granularity());
       return 0;
       }