
		BIND 9 PKCS #11 (Cryptoki) support

INTRODUCTION

PKCS #11 (Public Key Cryptography Standard #11) defines a platform-
independent API for the control of hardware security modules (HSMs)
and other cryptographic support devices. 

BIND 9 is known to work with two HSMs:  The Sun SCA 6000 cryptographic
acceration board, tested under Solaris x86, and the AEP Keyper
network-attached key storage device, tested with Debian Linux,
Solaris x86 and Windows Server 2003.

PREREQUISITES

See the HSM vendor documentation for information about installing,
initializing, testing and troubleshooting the HSM.

BIND 9 uses OpenSSL for cryptography, but stock OpenSSL does not
yet fully support PKCS #11.  However, a PKCS #11 engine for OpenSSL
is available from the OpenSolaris project.  It has been modified by
ISC to work with with BIND 9, and to provide new features such as
PIN management and key by reference.

The patched OpenSSL depends on a "PKCS #11 provider".  This is a shared
library object, providing a low-level PKCS #11 interface to the HSM
hardware.  It is dynamically loaded by OpenSSL at runtime.  The PKCS #11
provider comes from the HSM vendor, and and is specific to the HSM to be
controlled.

There are two "flavors" of PKCS #11 support provided by the patched
OpenSSL, one of which must be chosen at configuration time.  The correct
choice depends on the HSM hardware:

 - Use 'crypto-accelerator' with HSMs that have hardware cryptographic
   acceleration features, such as the SCA 6000 board.  This causes OpenSSL
   to run all supported cryptographic operations in the HSM.

 - Use 'sign-only' with HSMs that are designed to function primarily as
   secure key storage devices, but lack hardware acceleration.  These
   devices are highly secure, but are not necessarily any faster at
   cryptography than the system CPU--often, they are slower.  It is
   therefore most efficient to use them only for those cryptographic
   functions that require access to the secured private key, such as
   zone signing, and to use the system CPU for all other computationally-
   intensive operations.  The AEP Keyper is an example of such a device.

The modified OpenSSL code is included in the BIND 9.7.0b1 release, in the
form of a context diff against OpenSSL 0.9.8k.  Before building BIND 9
with PKCS #11 support, it will be necessary to build OpenSSL with this
patch in place and inform it of the path to the HSM-specific PKCS #11
provider library.

Obtain OpenSSL 0.9.8k:

    wget http://www.openssl.org/source/openssl-0.9.8k.tar.gz

Extract the tarball:

    tar zxf openssl-0.9.8k.tar.gz

Apply the patch from the BIND 9 release:

    patch -p1 -d openssl-0.9.8k \
            < bind-9.7.0b1/bin/pkcs11/openssl-0.9.8k-patch 

(Note that the patch file may not be compatible with the "patch"
utility on all operating systems.  You may need to install GNU patch.)

When building OpenSSL, place it in a non-standard location so that it
does not interfere with OpenSSL libraries elsewhere on the system.
In the following examples, we choose to install into "/opt/pkcs11/usr".
We will use this location when we configure BIND 9.

    EXAMPLE 1--BUILDING OPENSSL FOR THE AEP KEYPER ON LINUX:

    The AEP Keyper is a highly secure key storage device, but does
    not provide hardware cryptographic acceleration.  It can carry out
    cryptographic operations, but it is probably slower than your
    system's CPU.  Therefore, we choose the 'sign-only' flavor when
    building OpenSSL.

    The Keyper-specific PKCS #11 provider library is delivered with the
    Keyper software.  In this example, we place it /opt/pkcs11/usr/lib:

        cp pkcs11.GCC4.0.2.so.4.05 /opt/pkcs11/usr/lib/libpkcs11.so

    This library is only available for Linux as a 32-bit binary.  If we are
    compiling on a 64-bit Linux system, it is necessary to force a 32-bit
    build, by specifying -m32 in the build options.

    Finally, the Keyper library requires threads, so we must specify -pthread.
    
        cd openssl-0.9.8k
        ./Configure linux-generic32 -m32 -pthread \
            --pk11-libname=/opt/pkcs11/usr/lib/libpkcs11.so \
            --pk11-flavor=sign-only \
            --prefix=/opt/pkcs11/usr

    After configuring, run "make" and "make test".  If "make test" fails
    with "pthread_atfork() not found", you forgot to add the -pthread
    above.

    EXAMPLE 2--BUILDING OPENSSL FOR THE SCA 6000 ON SOLARIS:

    The SCA-6000 PKCS #11 provider is installed as a system library,
    libpkcs11. It is a true crypto accelerator, up to 4 times faster
    than any CPU, so the flavor shall be 'crypto-accelerator'.

    In this example, we are building on Solaris x86 on an AMD64 system.

        cd openssl-0.9.8k
        ./Configure solaris64-x86_64-cc \
            --pk11-libname=/usr/lib/64/libpkcs11.so \
            --pk11-flavor=crypto-accelerator \
            --prefix=/opt/pkcs11/usr

    (For a 32-bit build, use "solaris-x86-cc" and /usr/lib/libpkcs11.so.)

    After configuring, run "make" and "make test".

Once you have built OpenSSL, run "apps/openssl engine pkcs11" to confirm
that PKCS #11 support was compiled in correctly.  The output should be
one of the following lines, depending on the flavor selected:

        (pkcs11) PKCS #11 engine support (sign only)

Or:

        (pkcs11) PKCS #11 engine support (crypto accelerator)

Next, run "apps/openssl engine pkcs11 -t".  This will attempt to initialize
the PKCS #11 engine.  If it is able to do so successfully, it will report
"[ available ]".

If the output is correct, run "make install".

BUILDING BIND 9

When building BIND 9, the location of the custom-built OpenSSL
library must be specified via configure.

    EXAMPLE 3--CONFIGURING BIND 9 FOR LINUX

    To link with the PKCS #11 provider, threads must be enabled in the
    BIND 9 build.

    The PKCS #11 library for the AEP Keyper is currently only available as
    a 32-bit binary.  If we are building on a 64-bit host, we must force a
    32-bit build by adding "-m32" to the CC options on the "configure"
    command line.

        cd ../bind-9.7.0b1
        ./configure CC="gcc -m32" --enable-threads \
            --with-openssl=/opt/pkcs11/usr \
            --with-pkcs11=/opt/pkcs11/usr/lib/libpkcs11.so

    EXAMPLE 4--CONFIGURING BIND 9 FOR SOLARIS

    To link with the PKCS #11 provider, threads must be enabled in the
    BIND 9 build.

        cd ../bind-9.7.0b1
        ./configure CC="cc -xarch=amd64" --enable-threads \
            --with-openssl=/opt/pkcs11/usr \
            --with-pkcs11=/usr/lib/64/libpkcs11.so

    (For a 32-bit build, omit CC="cc -xarch=amd64".)

If configure complains about OpenSSL not working, you may have a 32/64-bit
architecture mismatch.  Or, you may have incorrectly specified the path to
OpenSSL (it should be the same as the --prefix argument to the OpenSSL
Configure).  

After configuring, run "make", "make test" and "make install".

PKCS #11 TOOLS

BIND 9 includes a minimal set of tools to operate the HSM, including
"pkcs11-keygen" to generate a new key pair within the HSM, "pkcs11-list"
to list objects currently available, and "pkcs11-destroy" to remove
objects.

In UNIX/Linux builds, these tools are built only if BIND 9 is configured
with the --with-pkcs11 option.  (NOTE: If --with-pkcs11 is set to "yes",
rather than to the path of the PKCS #11 provider, then the tools will be
built but the provider will be left undefined.  Use the -m option or the
PKCS11_PROVIDER environment variable to specify the path to the provider.)

USING THE HSM

First, we must set up the runtime environment so the OpenSSL and PKCS #11
libraries can be loaded:

    export LD_LIBRARY_PATH=/opt/pkcs11/usr/lib:${LD_LIBRARY_PATH}

When operating an AEP Keyper, it is also necessary to specify the
location of the "machine" file, which stores information about the Keyper
for use by PKCS #11 provider library.  If the machine file is in
/opt/Keyper/PKCS11Provider/machine, use:

    export KEYPER_LIBRARY_PATH=/opt/Keyper/PKCS11Provider

These environment variables must be set whenever running any tool
that uses the HSM, including pkcs11-keygen, pkcs11-list, pkcs11-destroy,
dnssec-keyfromlabel, dnssec-signzone, dnssec-keygen (which will use
the HSM for random number generation), and named.

We can now create and use keys in the HSM.  In this case, we will
create a 2048 bit key and give it the label "sample-ksk":

    pkcs11-keygen -b 2048 -l sample-ksk

To confirm that the key exists:

    pkcs11-list
    Enter PIN:
    object[0]: handle 2147483658 class 3 label[8] 'sample-ksk' id[0] 
    object[1]: handle 2147483657 class 2 label[8] 'sample-ksk' id[0] 

Before using this key to sign a zone, we must create a pair of BIND 9
key files.  The "dnssec-keyfromlabel" utility does this.  In this case,
we will be using the HSM key "sample-ksk" as the key-signing key for
"example.net":

    dnssec-keyfromlabel -l sample-ksk -f KSK example.net

The resulting K*.key and K*.private files can now be used to sign the
zone.  Unlike normal K* files, which contain both public and private
key data, these files will contain only the public key data, plus an
identifier for the private key which remains stored within the HSM.
The HSM handles signing with the private key.

If you wish to generate a second key in the HSM for use as a zone-signing
key, follow the same procedure above, using a different keylabel, a
smaller key size, and omitting "-f KSK" from the dnssec-keyfromlabel
arguments:

    pkcs11-keygen -b 1024 -l sample-zsk
    dnssec-keyfromlabel -l sample-zsk example.net

Alternatively, you may prefer to generate a conventional on-disk key,
using dnssec-keygen:

    dnssec-keygen example.net

This provides less security than an HSM key, but since HSMs can be
slow or cumbersome to use for security reasons, it may be more
efficient to reserve HSM keys for use in the less frequent
key-signing operation.  The zone-signing key can be rolled more
frequently, if you wish, to compensate for a reduction in key
security.

Now you can sign the zone.  (Note: If not using the -S option to
dnssec-signzone, it will be necessary to add the contents of both
K*.key files to the zone master file before signing it.)

    dnssec-signzone -S example.net
    Enter PIN:
    Verifying the zone using the following algorithms: NSEC3RSASHA1.
    Zone signing complete:
    Algorithm: NSEC3RSASHA1: ZSKs: 1, KSKs: 1 active, 0 revoked, 0 stand-by
    example.net.signed

SPECIFYING THE ENGINE ON THE COMMAND LINE

The OpenSSL engine can be specified in named and all of the dnssec-*
tools by using the "-E <engine>" command line option.  If BIND 9 is built
with the --with-pkcs11 option, this option defaults to "pkcs11".
Specifying the engine will generally not be necessary unless for
some reason you wish to use a different OpenSSL engine.

If you wish to disable use of the "pkcs11" engine--for troubleshooting
purposes, or because the HSM is unavailable--set the engine to the empty
string.  For example:

    dnssec-signzone -E '' -S example.net

This causes dnssec-signzone to run as if it were compiled without the
--with-pkcs11 option.

RUNNING NAMED WITH AUTOMATIC ZONE RE-SIGNING

If you want named to dynamically re-sign zones using HSM keys, and/or to
to sign new records inserted via nsupdate, then named must have access
to the HSM PIN.  This can be accomplished by placing the PIN into the
openssl.cnf file (in the above examples, /opt/pkcs11/usr/ssl/openssl.cnf).

The location of the openssl.cnf file can be overridden by setting the
OPENSSL_CONF environment variable before running named.

Sample openssl.cnf:

        openssl_conf = openssl_def
        [ openssl_def ]
        engines = engine_section
        [ engine_section ]
        pkcs11 = pkcs11_section
        [ pkcs11_section ]
        PIN = <PLACE PIN HERE>

This will also allow the dnssec-* tools to access the HSM without
PIN entry.  (The pkcs11-* tools access the HSM directly, not via
OpenSSL, so a PIN will still be required to use them.)

PLEASE NOTE:  Placing the HSM's PIN in a text file in this manner
may reduce the security advantage of using an HSM.  Be sure this
is what you want to do before configuring BIND 9 in this way.
