API:
#define CK_SECRET_MAX 20
#define CK_SECRET_LEN 16
/*
Vault that contains the secrets
*/
static unsigned char ck_secrets_vault[CK_SECRET_MAX][CK_SECRET_LEN];
/*
Creates and stores an amount of secrets
into the vault
*/
size_t ck_secrets_generate( size_t amount );
/*
Returns the amount of secrets in the vault
*/
size_t ck_secrets_count( void );
/*
Picks a random secret off the vault
*/
unsigned char *ck_secrets_random( void );
/*
Tests whether cookie matches on of the secrets
in the vault
*/
size_t ck_secrets_exist( unsigned char* peer, size_t plen,
unsigned char *cookie, size_t clen );Generate 20 secrets:
printf( "Generated %d cookie-secrets.\n", ck_secrets_generate( CK_SECRET_MAX ) );Generate a cookie with a random secret:
HMAC( EVP_sha256(), (const void*)ck_secrets_random(), CK_SECRET_LEN,
(const unsigned char*)buff, bufflen, result, &reslen );Test whether cookie matches one of our secrets:
if( ck_secrets_exist( buff, bufflen, cookie, clen ) == 1)
/* Cookie is valid since we found a matching secret */
else
/* Cookie is not valid */Credits to Robin Seggelmann & Michael Tuexen for their HMAC-generation snippet.