Hi Kunal,
> I was also wondering about the cipher block size. I was thinking
> of using 16 as block size, read the input ...
You have no choice. AES is a 16-byte block cipher.
Using the EVP_* functions is easier.
Jeff
On Fri, May 21, 2010 at 2:30 AM, ~ Kunal Sharma ~ <koolku...@gmail.com> wrote:
> David,
> Thanks for taking out time to review my code and reply.
> 1) I agree that using sizeof was a blunder on my part.
> 2) I'm calling decode2 with rg_conf_buf_dup and rg_conf_buf_dup_2, second
> one being the output buffer. So I'm certain that I don't modify the input
> buffer (though I just zero out only the part of my output buffer due to
> sizeof thing).
>
> I was also wondering about the cipher block size. I was thinking of using 16
> as block size, read the input buffer in chunks of block size one at a time,
> decrypt, copy and append to the output buffer. Do you think that would work
> ? Could I then use the buffer holding decrypted data in the decode2 function
> and get the original data back ? How can I get the size of decrypted buffer
> - strlen wouldn't work, I suppose ?
> Thanks,
> Kunal
>
> On Thu, May 20, 2010 at 8:38 PM, David Schwartz <dav...@webmaster.com>
> wrote:
>>
>> Kunal Sharma wrote:
>>
>>
>> void encode2(char *inbuf,char *outbuf)
>> {
>> unsigned char key32[] = "As different as chalk and cheese";
>> unsigned char iv[] = "As dark as pitch";
>>
>> AES_KEY aeskey;
>>
>> memset(outbuf, 0, sizeof(outbuf));
>>
>> AES_set_encrypt_key(key32, 32*8, &aeskey);
>>
>> AES_cbc_encrypt(inbuf, outbuf, strlen(inbuf), &aeskey, iv,
>> AES_ENCRYPT);
>>
>> return;
>> }
>>
>> You can't mean 'sizeof(outbuf)' -- 'outbuf' is a *pointer* to the output
>> buffer. What does the size of that pointer have to do with anything?
>>
>> void decode2(char *inbuf,char *outbuf,int len)
>> {
>> unsigned char key32[] = "As different as chalk and cheese";
>> unsigned char iv[] = "As dark as pitch";
>>
>> AES_KEY aeskey;
>>
>> memset(outbuf, 0, sizeof(outbuf));
>>
>> AES_set_decrypt_key(key32, 32*8, &aeskey);
>>
>> AES_cbc_encrypt(inbuf, outbuf, len, &aeskey, iv, AES_DECRYPT);
>>
>> return;
>> }
>>
>> Same use of 'sizeof(outbuf)' where that makes no sense (what does the size
>> of the pointer to the output buffer have to do with anything?). Also, what
>> happens if the plaintext is not a precise multiple of the cipher block
>> size?
>>
>> It seems like you have picked a low-level encryption/decryption function
>> where you wanted a high-level one.
>>
>> Also, you have one amusing boner. Your 'decode2' function tries to zero
>> the
>> output buffer, but actually only zeroes part of it. But you call it with
>> the
>> output buffer and input buffer the same! So you are actually erasing part
>> of
>> your input buffer before you use it!
>>
>> DS
>>
>> ______________________________________________________________________
>> OpenSSL Project http://www.openssl.org
>> User Support Mailing List openssl-us...@openssl.org
>> Automated List Manager majord...@openssl.org
>
>
______________________________________________________________________
OpenSSL Project http://www.openssl.org
User Support Mailing List openssl-users@openssl.org
Automated List Manager majord...@openssl.org
