All I can tell that as soon as I create certificates by the book:

http://dev.mysql.com/doc/refman/5.5/en/creating-ssl-certs.html

like this:

...
1005     openssl version
1006     mkdir cert
1007     cd cert
1008     openssl genrsa 2048 > ca-key.pem
1009     openssl req -new -x509 -nodes -days 3600          -key ca-key.pem -out ca-cert.pem
1010     openssl req -newkey rsa:2048 -days 3600          -nodes -keyout server-key.pem -out server-req.pem
1011     openssl rsa -in server-key.pem -out server-key.pem
1012     openssl x509 -req -in server-req.pem -days 3600          -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out server-cert.pem
1013     openssl req -newkey rsa:2048 -days 3600          -nodes -keyout client-key.pem -out client-req.pem
1014     openssl rsa -in client-key.pem -out client-key.pem
1015     openssl x509 -req -in client-req.pem -days 3600          -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out client-cert.pem
1016     openssl verify -CAfile ca-cert.pem server-cert.pem client-cert.pem
...

everything works:

[openxs@chief msb_5_5_30]$ ./use -uroot test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.5.30-rel30.2 Percona Server with XtraDB (GPL), Release rel30.2, Revision 500

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql [localhost] {root} (test) > grant all privileges on test.* to 'user'@'localhost' identified by 'user' require ssl;
Query OK, 0 rows affected (0.00 sec)

mysql [localhost] {root} (test) > exit
Bye
[openxs@chief msb_5_5_30]$ ./use -uuser -puser test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.5.30-rel30.2 Percona Server with XtraDB (GPL), Release rel30.2, Revision 500

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql [localhost] {user} (test) > select current_user();
+----------------+
| current_user() |
+----------------+
| user@localhost |
+----------------+
1 row in set (0.00 sec)

mysql [localhost] {user} (test) > show status like 'ssl_cipher';
+---------------+--------------------+
| Variable_name | Value              |
+---------------+--------------------+
| Ssl_cipher    | DHE-RSA-AES256-SHA |
+---------------+--------------------+
1 row in set (0.00 sec)

mysql [localhost] {user} (test) > status
--------------
/home/openxs/5.5.30/bin/mysql  Ver 14.14 Distrib 5.5.30, for Linux (x86_64) using readline 5.1

Connection id:          6
Current database:       test
Current user:           user@localhost
SSL:                    Cipher in use is DHE-RSA-AES256-SHA
Current pager:          stdout
Using outfile:          ''
Using delimiter:        ;
Server version:         5.5.30-rel30.2 Percona Server with XtraDB (GPL), Release rel30.2, Revision 500
Protocol version:       10
Connection:             Localhost via UNIX socket
Server characterset:    latin1
Db     characterset:    latin1
Client characterset:    utf8
Conn.  characterset:    utf8
UNIX socket:            /tmp/mysql_sandbox5530.sock
Uptime:                 4 min 50 sec

Threads: 1  Questions: 40  Slow queries: 0  Opens: 33  Flush tables: 1  Open tables: 26  Queries per second avg: 0.137
--------------

mysql [localhost] {user} (test) > exit
Bye

Details of my environment:

[openxs@chief msb_5_5_30]$ cat /etc/issue
Fedora release 14 (Laughlin)
Kernel \r on an \m (\l)

[openxs@chief msb_5_5_30]$ uname -a
Linux chief 2.6.35.14-106.fc14.x86_64 #1 SMP Wed Nov 23 13:07:52 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
[openxs@chief msb_5_5_30]$ openssl version
OpenSSL 1.0.0e-fips 6 Sep 2011
[openxs@chief msb_5_5_30]$ openssl verify -CAfile /home/openxs/cert/ca-cert.pem /home/openxs/cert/server-cert.pem /home/openxs/cert/client-cert.pem
/home/openxs/cert/server-cert.pem: OK
/home/openxs/cert/client-cert.pem: OK
[openxs@chief msb_5_5_30]$ cat my.sandbox.cnf
#    The MySQL Sandbox
#    Copyright (C) 2006-2013 Giuseppe Maxia
#    Contacts: http://datacharmer.org
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; version 2 of the License
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

[mysql]
prompt='mysql [\h] {\u} (\d) > '
#

[client]
user            = msandbox
password        = msandbox
port            = 5530
socket          = /tmp/mysql_sandbox5530.sock
ssl-ca=/home/openxs/cert/ca-cert.pem
ssl-cert=/home/openxs/cert/client-cert.pem
ssl-key=/home/openxs/cert/client-key.pem

[mysqld]
user                            = openxs
port                            = 5530
socket                          = /tmp/mysql_sandbox5530.sock
basedir                         = /home/openxs/5.5.30
datadir                         = /home/openxs/sandboxes/msb_5_5_30/data
tmpdir                          = /home/openxs/sandboxes/msb_5_5_30/tmp
pid-file                        = /home/openxs/sandboxes/msb_5_5_30/data/mysql_sandbox5530.pid
#log-slow-queries               = /home/openxs/sandboxes/msb_5_5_30/data/msandbox-slow.log
#log                            = /home/openxs/sandboxes/msb_5_5_30/data/msandbox.log
#
# additional options passed through 'my_clause'
#
log-error=msandbox.err
ssl-ca=/home/openxs/cert/ca-cert.pem
ssl-cert=/home/openxs/cert/server-cert.pem
ssl-key=/home/openxs/cert/server-key.pem

[openxs@chief msb_5_5_30]$ openssl x509 -text -in /home/openxs/cert/client-cert.pem | grep CN
        Issuer: C=UA, ST=KIEV, L=KIEV, O=Percona One, OU=support, CN=chief1/emailAddress=vk1@a.com
        Subject: C=UA, ST=KIEV, L=KIEV, O=Percona Three, OU=support, CN=chief3/emailAddress=vk2@a.com

It had been like that all the time for me. So I continue to assume that problem is with certificates that are "not OK" for OpenSSL library used in the system (while they were "OK" for yassl), or with OpenSSL version used itself.