12-29-2006
Password-based challenge-response
Hello all,
I have this question, hope to get some guidance...
Fora simple password-based challenge-response protocol between a user A
and a server S, where Pa is A's password, n is a random nonce generated
by the server, and h is a known cryptographic hash function.
1. S -> A: E(Pa,n)
2. A -> S: E(Pa,h(n))
How to show that this protocol is vulnerable to an off-line password
guessing attack? and how would the attack take place ?. Under which
circumstances would the vulnerability not be a problem?
thanks for reading...
cheers.
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LEARN ABOUT MOJAVE
sasl_checkapop
sasl_checkapop(3) SASL man pages sasl_checkapop(3)
NAME
sasl_checkapop - Check an APOP challenge/response
SYNOPSIS
#include <sasl/sasl.h>
int sasl_checkapop(sasl_conn_t *conn,
const char *challenge,
unsigned challen,
const char *response,
unsigned resplen);
DESCRIPTION
sasl_checkapop() will check an APOP challenge/response. APOP is an optional POP3 (RFC 1939) authentication command which uses a shared
secret (password). The password is stored in the SASL secrets database. For information on the SASL shared secrets database see the System
Administrators Guide in the doc/ directory of the SASL distribution.
If called with a NULL challenge, sasl_checkapop() will check to see if the APOP mechanism is enabled.
RETURN VALUE
sasl_checkapop returns an integer which corresponds to one of the following codes. SASL_OK indicates that the authentication is complete.
All other return codes indicate errors and should either be handled or the authentication session should be quit. See sasl_errors(3) for
meanings of return codes.
CONFORMING TO
RFC 4422, RFC 1939
SEE ALSO
sasl(3), sasl_errors(3)
SASL
29 June 2001 sasl_checkapop(3)