<div dir="ltr">Hi, I have following problem in initialisation vector(IV) XOR with first block of text,<div><br></div><div>The assignment ask us for aes-256-cbc mode, that's means we encrypt/de 32 bytes of block text each time, but I got 16 bytes of IV by using EVP_BytesToKey with SHA1, the SHA1 could generate 160bit, witch is also not enough for XOR with 256bit of text. SHA256 is just fit. but assignment ask us use SHA1.</div>
<div>After searching online, I found that the evp.h define the EVP_MAX_IV_LENGTH is 16 bytes, even when I used SHA256, EVP_BytesToKey still generate 16 bytes. so I don't know how to XOR between IV and text with different length now.</div>
<div><br></div><div>Any ideas?</div><div>Thank you.</div><div>Kun</div></div>