Problem - Kevin Tafuro

key
Pointer to the encryption key to be used.
ivornonce
Pointer to an initialization vector or none, if appropriate (use NULL otherwise).
For CBC, CFB, and OFB modes, the initialization vector or nonce is always the
same size as the block size of the cipher, which is often different from the key
size of the cipher.
There are also deprecated versions of these calls, EVP_EncryptInit( ) and EVP_
DecryptInit( ), that are the same except that they do not take the engine argument,
and they use only the built-in software implementation.
Calling a function that returns an EVP_CIPHER object will cause the cipher’s implementation
to load dynamically and place information about the algorithm into an
internal table if it has not yet done so. Alternatively, you can load all possible symmetric
ciphers at once with a call to the function OpenSSL_add_all_ciphers( ), or all
ciphers and message digest algorithms with a call to the function OpenSSL_add_all_
algorithms( ) (neither function takes any arguments). For algorithms that have been
loaded, you can retrieve pointers to their objects by name using the EVP_get_
cipherbyname( ) function, which takes a single parameter of type char *, representing
the desired cipher configuration.
Table 5-6 summarizes the possible functions that can load ciphers (if necessary) and
return EVP_CIPHER objects. The table also shows the strings that can be used to look
up loaded ciphers.
As noted in Recipe 5.2, we personally recommend AES-based solutions,
or (of the ciphers OpenSSLoffers) Triple-DES if AES is not
appropriate. If you use other algorithms, be sure to research them
thoroughly.
Table 5-6. Cipher instantiation reference
Key strength /
actual size (if
Cipher lookup
Cipher
different) Cipher mode Call for EVP_CIPHER object
string
AES 128 bits ECB EVP_aes_128_ecb( ) aes-128-ecb
AES 128 bits CBC EVP_aes_128_cbc( ) aes-128-cbc
AES 128 bits CFB EVP_aes_128_cfb( ) aes-128-cfb
AES 128 bits OFB EVP_aes_128_ofb( ) aes-128-ofb
AES 192 bits ECB EVP_aes_192_ecb( ) aes-192-ecb
AES 192 bits CBC EVP_aes_192_cbc( ) aes-192-cbc
AES 192 bits CFB EVP_aes_192_cfb( ) aes-192-cfb
AES 192 bits OFB EVP_aes_192_ofb( ) aes-192-ofb
AES 256 bits ECB EVP_aes_256_ecb( ) aes-256-ecb
Performing Block Cipher Setup (for CBC, CFB, OFB, and ECB Modes) in OpenSSL | 223
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