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Rebuilding openssl with Elliptic Curves on CentOS 6.4

The strategy is:

1) Download the "official" CentOS source package (.src.rpm)
2) Modify the .spec file to enable elliptic curves. (change no-EC to enable-EC)
3) Rebuild the package using mock. 

The build is performed on a fresh Amazon Cloud server which allows anyone to precisely duplicate every step that is taken below.

# 1. Log into AWS (Amazon Web Services) and create a public key. 
# 2. Download your public key and install into your local client e.g. putty or ssh.
# 3. Instantiate a CentOS 6.4 machine using AWS marketplace for machine images. (free)
# 4. Log into your new Centos 6.4 using ssh or putty, update and install a few packages:

Update the newly installed Centos and install development tools

yum -y update  # Update all packages on a new machine
yum -y groupinstall 'Development tools'

Install mock, a super package builder, from the Fedora EPEL repository. Mock is the secret weapon of CentOS (and many other distros) package builders.

yum -y localinstall --nogpgcheck http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm # Install EPEL (EL6 extra packages) repository 
yum -y install fedora-packager  # Install mock from EPEL repository

Make a new user "abcd" added to group "mock". User abcd will be used for package rebuilding. Note: group "mock" was automatically created by yum when we installed fedora-packager.

userdel -rf abcd ; useradd -G mock abcd ; su abcd

Fetch the latest CentOS openssl source package and "unpack" it with mock

cd ~ ; curl -O http://vault.centos.org/6.4/os/Source/SPackages/openssl-1.0.0-27.el6.src.rpm
/usr/bin/mock --rebuild ~/openssl-1.0.0-27.el6.src.rpm

We see output lines like this

# INFO: mock.py version 1.1.32 starting...
# Start: build setup for openssl-1.0.0-27.el6.src.rpm
# Start: rpmbuild -bb openssl-1.0.0-27.el6.src.rpm
# Start: Outputting list of installed packages

Finally, after a long time, we see

# INFO: Results and/or logs in: /var/lib/mock/epel-6-x86_64/result

Move the mock build results to a safe place

rm -rf /home/abcd/build ; mv /var/lib/mock/epel-6-x86_64/root/builddir/build/ /home/abcd ; # Move to a safe place

Download a replacement source file (.tar.gz) and a patch file from openssl.org

cd /home/abcd/build/SOURCES
curl -O http://www.openssl.org/source/openssl-1.0.0.tar.gz # Download corresponding source tarball from openssl
curl -o patch300.patch http://cvs.openssl.org/patchset?cn=19998 # Download this patch to fix a test error

Edit the openssl.spec file to

# 1. Enable elliptic curves (enable-EC)
# 2. Disable the hobble-openssl script (which erases EC files)
# 3. Update the release mumber to .EC.1
# 4. Include the newly downloaded .tar.bz as source
# 5. Include the newly downloaded patch file

cd ../SPECS
sed -i -e "s/no-ec/enable-ec/; s/no-ecdh/enable-ecdh/; s/no-ecdsa/enable-ecdsa/" openssl.spec # Enable EC
sed -i -e "s/^Source1: hobble-openssl/#&/; s/^%.SOURCE1. /#&/" openssl.spec # Disable the "hobble" script
sed -i -e "s/^Release.*dist\}/&.EC.1/" openssl.spec # Also change release number by adding .EC.1
sed -i -e "s/-usa.tar.bz2/.tar.gz/" openssl.spec # Change the source tarball
sed -i -e "s/^Patch78.*/&\nPatch300: patch300.patch\n/" openssl.spec # Add the new patch
sed -i -e "s/^%patch78.*/&\n%patch300 -p1 \n/" openssl.spec # Add the new patch again

Ceate a new source package using the edited ("enable-EC") openssl.spec

/usr/bin/mock --buildsrpm --spec  ~/build/SPECS/openssl.spec --sources  ~/build/SOURCES # Do a source rebuild

Use the new source package to create a new openssl package

cp /var/lib/mock/epel-6-x86_64/root/builddir/build/SRPMS/openssl-1.0.0-27.el6.EC.1.src.rpm /home/abcd
cd ~ ; /usr/bin/mock --rebuild openssl-1.0.0-27.el6.EC.1.src.rpm

Summarized here http://pastebin.centos.org/3070

Thanks to pj on Freenode for all the help.

share|improve this question
1  
Why are you not using mock to build the package? –  Ignacio Vazquez-Abrams Jun 29 '13 at 1:39
1  
1. cough 2. It will flatten a good chunk of the curve. 3. It was used to build the package in the first place. –  Ignacio Vazquez-Abrams Jun 29 '13 at 1:47
    
Yes, you should install mock from EPEL. The CentOS maintainers and EPEL maintainers have an understanding in that they generally don't step on each other's toes (plus, there is a decent amount of overlap in the groups). –  Ignacio Vazquez-Abrams Jun 29 '13 at 2:43
    
Don't forget to modify the release value in your modified spec file (e.g. 27elliptical). –  Ignacio Vazquez-Abrams Jun 29 '13 at 4:26
    
Perform most of this, except use -bs instead of -bb after editing the spec file, and rebuild the resultant SRPM with mock. –  Ignacio Vazquez-Abrams Jun 29 '13 at 5:38
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