Fix decrypt in FFI/Python. Github issue 53

2 files changed, 7 insertions, 1 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index 6c29a6f7e..c5a862200 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -393,7 +393,8 @@ int botan_cipher_init(botan_cipher_t* cipher, const char* cipher_name, uint32_t
    {
    try
       {
-      Botan::Cipher_Dir dir = (flags & 0) ? Botan::DECRYPTION : Botan::ENCRYPTION;
+      const bool encrypt_p = ((flags & BOTAN_CIPHER_INIT_FLAG_MASK_DIRECTION) == BOTAN_CIPHER_INIT_FLAG_ENCRYPT);
+      const Botan::Cipher_Dir dir = encrypt_p ? Botan::ENCRYPTION : Botan::DECRYPTION;
       std::unique_ptr<Botan::Cipher_Mode> mode(Botan::get_cipher_mode(cipher_name, dir));
       if(!mode)
          return -1;
@@ -469,6 +470,7 @@ int botan_cipher_update(botan_cipher_t cipher_obj,
          {
          mbuf.assign(input, input + input_size);
          *input_consumed = input_size;
+         *output_written = 0;
 
          try
             {
diff --git a/src/lib/ffi/ffi.h b/src/lib/ffi/ffi.h
index 9ba02f02c..b4e99defd 100644
--- a/src/lib/ffi/ffi.h
+++ b/src/lib/ffi/ffi.h
@@ -90,6 +90,10 @@ BOTAN_DLL int botan_mac_destroy(botan_mac_t mac);
 */
 typedef struct botan_cipher_struct* botan_cipher_t;
 
+#define BOTAN_CIPHER_INIT_FLAG_MASK_DIRECTION 1
+#define BOTAN_CIPHER_INIT_FLAG_ENCRYPT 0
+#define BOTAN_CIPHER_INIT_FLAG_DECRYPT 1
+
 BOTAN_DLL int botan_cipher_init(botan_cipher_t* cipher, const char* name, uint32_t flags);
 
 BOTAN_DLL int botan_cipher_valid_nonce_length(botan_cipher_t cipher, size_t nl);