Issue on EVP_CIPHER_CTX

[Andrea Saracino]

Hello to everyone,
I'm finding some issues using the symmetric encryption and decryption
routines EVP_encrypt/decrypt. Here is the code of the function that I'm
calling:

int cipher :: symm_encrypt(){
  EVP_CIPHER_CTX_init(symm_ctx);
  init_symm_cipher(symm_encryption_alg);
  int cipher_text_length;
  int tmp_len;
  if(!EVP_EncryptUpdate(symm_ctx, buffer, &cipher_text_length, (unsigned
char*) data.c_str(), MAX_MSG_SIZE))
      return 0;
  if(!EVP_EncryptFinal_ex(symm_ctx, buffer + cipher_text_length,
&tmp_len))
      return 0;
  EVP_CIPHER_CTX_cleanup(symm_ctx);
  return 1;
}

Buffer is an unsigned char * dinamically initialized with: new unsigned char
[4096]
symm_encryption_alg is EVP_bf_cbc()
symm_ctx is EVP_CIPHER_CTX_new();

Well it seems that after the execution of this function something spurious
is written in memory, infact if I call the destructor of my class object
"cipher" without calling this function everything works fine, otherwise
sometimes I'm obtaining a segmentation fault.

Using Valgrind it reports several errors about the function BF_encrypt()
about the use of 4 unititialized bytes.

Are there known issues about this function that could be related to this
problem?

Thanks in advance.

Best Regards.

Andrea Saracino