synchronous encryption algorithm vs. non-synchronous

whysyn · 02-22-2007, 10:32 AM

What is the difference? How can I tell if an algorithm is synchronous or not?

In OpenSSL, it lists the following as ciphers, but which are synchronous, and what is currently accepted as the strongest?

Code:

bf bf-cbc bf-cfb bf-ecb bf-ofb
Blowfish Cipher

cast cast-cbc
CAST Cipher

cast5-cbc cast5-cfb cast5-ecb cast5-ofb
CAST5 Cipher

des des-cbc des-cfb des-ecb des-ede des-ede-cbc des-ede-cfb des-ede-ofb des-ofb
DES Cipher

des3 desx des-ede3 des-ede3-cbc des-ede3-cfb des-ede3-ofb
Triple-DES Cipher

idea idea-cbc idea-cfb idea-ecb idea-ofb
IDEA Cipher

rc2 rc2-cbc rc2-cfb rc2-ecb rc2-ofb
RC2 Cipher

rc4
RC4 Cipher

rc5 rc5-cbc rc5-cfb rc5-ecb rc5-ofb
RC5 Cipher

Matir · 02-22-2007, 10:33 AM

Perhaps you mean symmetric vs asymmetric encryption? Asymmetric is better known as public key cryptography: separate keys are used to encrypt and decrypt. In symmetric crypto, the same key is used both ways.

whysyn · 02-22-2007, 10:42 AM

Thanks for your fast response!

Let me give you a bit of background. I'm working on setting up drive encryption, using mounting by pam_mount without having the key tied to the user password, and without having to prompt the user for separate authentication to unlock their drive space.

The document states: "an OpenSSL-supported synchronous encryption/decryption algorithm, bf-ecb, for example."

What I'm really trying to figure out is: what is the strongest encryption I can use here?