The <isc/md.h> header directly included <openssl/evp.h> header which
enforced all users of the libisc library to explicitly list the include
path to OpenSSL and link with -lcrypto. By hiding the specific
implementation into the private namespace, we no longer enforce this.
In the long run, this might also allow us to switch cryptographic
library implementation without affecting the downstream users.
While making the isc_md_type_t type opaque, the API using the data type
was changed to use the pointer to isc_md_type_t instead of using the
type directly.
This commit reverts the previous change to use system provided
entropy, as (SYS_)getrandom is very slow on Linux because it is
a syscall.
The change introduced in this commit adds a new call isc_nonce_buf
that uses CSPRNG from cryptographic library provider to generate
secure data that can be and must be used for generating nonces.
Example usage would be DNS cookies.
The isc_random() API has been changed to use fast PRNG that is not
cryptographically secure, but runs entirely in user space. Two
contestants have been considered xoroshiro family of the functions
by Villa&Blackman and PCG by O'Neill. After a consideration the
xoshiro128starstar function has been used as uint32_t random number
provider because it is very fast and has good enough properties
for our usage pattern.
The other change introduced in the commit is the more extensive usage
of isc_random_uniform in places where the usage pattern was
isc_random() % n to prevent modulo bias. For usage patterns where
only 16 or 8 bits are needed (DNS Message ID), the isc_random()
functions has been renamed to isc_random32(), and isc_random16() and
isc_random8() functions have been introduced by &-ing the
isc_random32() output with 0xffff and 0xff. Please note that the
functions that uses stripped down bit count doesn't pass our
NIST SP 800-22 based random test.
The three functions has been modeled after the arc4random family of
functions, and they will always return random bytes.
The isc_random family of functions internally use these CSPRNG (if available):
1. getrandom() libc call (might be available on Linux and Solaris)
2. SYS_getrandom syscall (might be available on Linux, detected at runtime)
3. arc4random(), arc4random_buf() and arc4random_uniform() (available on BSDs and Mac OS X)
4. crypto library function:
4a. RAND_bytes in case OpenSSL
4b. pkcs_C_GenerateRandom() in case PKCS#11 library
4183. [cleanup] Use timing-safe memory comparisons in cryptographic
code. Also, the timing-safe comparison functions have
been renamed to avoid possible confusion with
memcmp(). [RT #40148]
3705. [func] "configure --enable-native-pkcs11" enables BIND
to use the PKCS#11 API for all cryptographic
functions, so that it can drive a hardware service
module directly without the need to use a modified
OpenSSL as intermediary (so long as the HSM's vendor
provides a complete-enough implementation of the
PKCS#11 interface). This has been tested successfully
with the Thales nShield HSM and with SoftHSMv2 from
the OpenDNSSEC project. [RT #29031]
digest length were used incorrectly, leading to
interoperability problems with other DNS
implementations. This has been corrected.
(Note: If an oversize key is in use, and
compatibility is needed with an older release of
BIND, the new tool "isc-hmac-fixup" can convert
the key secret to a form that will work with all
versions.) [RT #20751]
private key file format, to allow implementation
of explicit key rollover in a future release
without impairing backward or forward compatibility.
[RT #20310]
