Revert part of 5be6e329324fc8263de56167091754e27305917b,

AEAD_Mode::start now returns a value again. While not useful for any
current modes it allows future flexibility of presenting
protoocol-level concepts (eg, OpenPGP encryption) using the AEAD
interface.

2 files changed, 4 insertions, 2 deletions

diff --git a/src/aead/ocb/ocb.cpp b/src/aead/ocb/ocb.cpp
index 20f54dca7..4cbd8bde8 100644
--- a/src/aead/ocb/ocb.cpp
+++ b/src/aead/ocb/ocb.cpp
@@ -215,7 +215,7 @@ void OCB_Mode::set_associated_data(const byte ad[], size_t ad_len)
    m_ad_hash = ocb_hash(*m_L, *m_cipher, &ad[0], ad_len);
    }
 
-void OCB_Mode::start(const byte nonce[], size_t nonce_len)
+secure_vector<byte> OCB_Mode::start(const byte nonce[], size_t nonce_len)
    {
    if(!valid_nonce_length(nonce_len))
       throw Invalid_IV_Length(name(), nonce_len);
@@ -225,6 +225,8 @@ void OCB_Mode::start(const byte nonce[], size_t nonce_len)
    m_offset = m_nonce_state->update_nonce(nonce, nonce_len);
    zeroise(m_checksum);
    m_block_index = 0;
+
+   return secure_vector<byte>();
    }
 
 void OCB_Encryption::encrypt(byte buffer[], size_t blocks)
diff --git a/src/aead/ocb/ocb.h b/src/aead/ocb/ocb.h
index 597cd9c52..d50710a79 100644
--- a/src/aead/ocb/ocb.h
+++ b/src/aead/ocb/ocb.h
@@ -30,7 +30,7 @@ class Nonce_State;
 class BOTAN_DLL OCB_Mode : public AEAD_Mode
    {
    public:
-      void start(const byte nonce[], size_t nonce_len) override;
+      secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
 
       void set_associated_data(const byte ad[], size_t ad_len) override;