A question about openssl, pls help me

Question

hi,all
I'm a student from China. Now I dowload the openssl package to study the cryptography algorithm. I have read some books such as Applied Cryptography by Bruce Schneier. But Mr. Eric Young's programs make me in sea, e.g. in CAST program package, there are CAST_ecb_encrypt , CAST_cfb64_encrypt , CAST_cbc_encrypt and CAST_ofb64_encrypt function. Which should I use ?
I teach myself Cryptography, so none can answer my question. Can you help me?
Thanx!

Answer 1

void CAST_set_key(CAST_KEY key, int len, const unsigned char data);
void CAST_ecb_encrypt(const unsigned char in,unsigned char out,CAST_KEY *key
          int enc);
void CAST_encrypt(CAST_LONG data,CAST_KEY key);
void CAST_decrypt(CAST_LONG data,CAST_KEY key);
void CAST_cbc_encrypt(const unsigned char in, unsigned char out, long length
          CAST_KEY ks, unsigned char iv, int enc);
void CAST_cfb64_encrypt(const unsigned char in, unsigned char out,
               long length, CAST_KEY schedule, unsigned char ivec,
               int *num, int enc);
void CAST_ofb64_encrypt(const unsigned char in, unsigned char out,
               long length, CAST_KEY schedule, unsigned char ivec,
               int *num);