A method is provided for securely accessing code in an external memory. In the method, plaintext code may be stored in internal memory as sets of multiple blocks, each of the multiple blocks having N-bits. The code is encrypted and stored in the external memory. A block cipher having an authenticated encryption mode is used to convert the plaintext code to ciphertext code plus an authentication tag corresponding to each set of the multiple blocks. The external memory is formatted to store the ciphertext and the authentication tag. A translated address for the ciphertext is created from a plaintext address. During a read operation, the generated authentication tag is checked with an expected authentication tag. If the check is successful, the ciphertext code is decrypted and provided to a CPU for execution as plaintext code. In one embodiment, the CPU executes the plaintext code “in place” in the external memory.