commit 0196647970a91d2bdb052f38b3749dd0e99348e4 Author: Roger Dingledine <arma@torproject.org> Date: Sun Mar 10 16:28:28 2013 -0400 start part-way through the ssl cert lifetime also, snap the start time and end time to a day boundary, since most certs in the wild seem to do this. --- src/common/tortls.c | 16 +++++++++++----- src/or/router.c | 14 ++++++++++++-- 2 files changed, 23 insertions(+), 7 deletions(-) diff --git a/src/common/tortls.c b/src/common/tortls.c index 94cedba..a08910b 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -234,7 +234,7 @@ static X509* tor_tls_create_certificate(crypto_pk_t *rsa, crypto_pk_t *rsa_sign, const char *cname, const char *cname_sign, - unsigned int lifetime); + unsigned int cert_lifetime); static int tor_tls_context_init_one(tor_tls_context_t **ppcontext, crypto_pk_t *identity, @@ -608,9 +608,10 @@ tor_x509_name_new(const char *cname) /** Generate and sign an X509 certificate with the public key <b>rsa</b>, * signed by the private key <b>rsa_sign</b>. The commonName of the * certificate will be <b>cname</b>; the commonName of the issuer will be - * <b>cname_sign</b>. The cert will be valid for <b>cert_lifetime</b> seconds - * starting from now. Return a certificate on success, NULL on - * failure. + * <b>cname_sign</b>. The cert will be valid for <b>cert_lifetime</b> + * seconds, starting from some time in the past. + * + * Return a certificate on success, NULL on failure. */ static X509 * tor_tls_create_certificate(crypto_pk_t *rsa, @@ -632,7 +633,12 @@ tor_tls_create_certificate(crypto_pk_t *rsa, tor_tls_init(); - start_time = time(NULL); + /* Make sure we're part-way through the certificate lifetime, rather + * than having it start right now. Don't choose quite uniformly, since + * then we might pick a time where we're about to expire. Lastly, be + * sure to start on a day boundary. */ + start_time = time(NULL) - crypto_rand_int(cert_lifetime) + 2*24*3600; + start_time -= start_time % (24*3600); tor_assert(rsa); tor_assert(cname); diff --git a/src/or/router.c b/src/or/router.c index 2113663..422fe5d 100644 --- a/src/or/router.c +++ b/src/or/router.c @@ -660,8 +660,18 @@ router_initialize_tls_context(void) flags |= TOR_TLS_CTX_USE_ECDHE_P224; } if (!lifetime) { /* we should guess a good ssl cert lifetime */ - /* choose between 1 and 365 days */ - lifetime = 1*24*3600 + crypto_rand_int(364*24*3600); + + /* choose between 5 and 365 days, and round to the day */ + lifetime = 5*24*3600 + crypto_rand_int(361*24*3600); + lifetime -= lifetime % (24*3600); + + if (crypto_rand_int(2)) { + /* Half the time we expire at midnight, and half the time we expire + * one second before midnight. (Some CAs wobble their expiry times a + * bit in practice, perhaps to reduce collision attacks; see ticket + * 8443 for details about observed certs in the wild.) */ + lifetime--; + } } /* It's ok to pass lifetime in as an unsigned int, since