trouble with encrypted password

hello everybody, i ve got trouble with encrypted password. I want to manage users with password wich are more longer than 8 caracters. When i use radcrypt (based on crypt), it doesn't work. It's normal due to limitation of crypt. I must cut password to 8 caracters for make running. When i use radcrypt with MD5 encryption , it doesn't run : indeed the encrypted string generated by MD5 radcrypt is more than 16 caracters. How can i use encrypted password without limited password to 8 caracters ? Cheers