(Or you manually have to apply a HMAC after the encryption under a separate key.) So you usually want a mode like EAX, CCM, or GCM. Second, you can use a mode like CBC, but the ciphertext will lack integrity and authenticity assurances.
And it does not suffer endianess issues on obscure platforms. The EVP_* functions use hardware acceleration, like AES-NI, if available. Finally, its subject to endianess issues on some obscure platforms. Additionally, it's a software-only routine, and it will never use hardware acceleration, like AES-NI. This answer is kind of popular, so I'm going to offer something more up-to-date since OpenSSL added some modes of operation that will probably help you.įirst, don't use AES_encrypt and AES_decrypt. I am trying to write a sample program to do AES encryption using Openssl.
algorithm API for symmetric crypto nicely explained by Daniel in one of the question asked by me. Check out the reason for doing this here OpenSSL using EVP vs. One more suggestion from the code you posted above i see you are using the api from aes.h This helped me a lot actually understanding the reasons behind using various functions and structures of EVP.Īnd if you want to dive deep into the Openssl crypto library, i suggest download the code from the openssl website (the version installed on your machine) and then look in the implementation of EVP and aeh api implementation. The code is detailed enough with comments and if you still need much explanation about the API itself i suggest check out this book Network Security with OpenSSL by Viega/Messier/Chandra (google it you will easily find a pdf of this.) read chapter 6 which is specific to symmetric ciphers using EVP API. PS: I don't get any errors upon compilation. I went through the code and found the API's using which i wrote a small program as below (please omit the line numbers). I tried going through Openssl documentation( it's a pain), could not figure out much.
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