When using the API, you need to be very careful about the length of the data. I was confused when I first used it. I made a note for this article. Generally there are no parameters of the specified length. The default is 16 ( AES_BLOCK_SIZE) bytes. The length of the output data is usually a multiple of 16 bytes, otherwise the array will be out of bounds.
In the following APIs, encrypt means encryption and decrypt means decryption.
1. Generate an encryption/decryption key
int AES_set_encrypt_key(const unsigned char *userKey, const int bits,
AES_KEY *key);
int AES_set_decrypt_key(const unsigned char *userKey, const int bits,
AES_KEY *key);
AES_KEY *key);
int AES_set_decrypt_key(const unsigned char *userKey, const int bits,
AES_KEY *key);
2. Use AES encryption / decryption
void AES_encrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);
void AES_decrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);
const AES_KEY *key);
void AES_decrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);
3. Use AES CBC encryption/decryption
void AES_encrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);
void AES_decrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);
const AES_KEY *key);
void AES_decrypt(const unsigned char *in, unsigned char *out,
const AES_KEY *key);