Dovecot crashes at connect with TLS (Possible Bug)

Hello all,

I am using Dovecot with enabled SSL/TLS support on a Ubuntu 14.04 Server Trusty Tahr system. Dovecot in general works but it crashes when I try to establish a connection with enabled TLS.

I have created a self signed certificate and a key with the following command:

openssl req -new -x509 -days 3650 -nodes -newkey rsa:4096 -out /etc/ssl/certs/mail.pem -keyout /etc/ssl/private/mail.pem

I configured this in Postfix and Dovecot. Postfix works fine with it. In both cases a tweaked the crypto settings a bit to have better ciphers, key-exchange ciphers and so on prefered. In Postfix all works well.

My Dovecot SSL settings look like this (/etc/dovecot/conf.d/10-ssl.conf):

##
## SSL settings
##

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = yes

# PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
# dropping root privileges, so keep the key file unreadable by anyone but
# root. Included doc/mkcert.sh can be used to easily generate self-signed
# certificate, just make sure to update the domains in dovecot-openssl.cnf
ssl_cert = </etc/ssl/private/mail.pem
ssl_key = </etc/ssl/private/mail.pem

# If key file is password protected, give the password here. Alternatively
# give it when starting dovecot with -p parameter. Since this file is often
# world-readable, you may want to place this setting instead to a different
# root owned 0600 file by using ssl_key_password = <path.
#ssl_key_password =

# PEM encoded trusted certificate authority. Set this only if you intend to use
# ssl_verify_client_cert=yes. The file should contain the CA certificate(s)
# followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem)
#ssl_ca =

# Require that CRL check succeeds for client certificates.
#ssl_require_crl = yes

# Directory and/or file for trusted SSL CA certificates. These are used only
# when Dovecot needs to act as an SSL client (e.g. imapc backend). The
# directory is usually /etc/ssl/certs in Debian-based systems and the file is
# /etc/pki/tls/cert.pem in RedHat-based systems.
#ssl_client_ca_dir =
#ssl_client_ca_file =

# Request client to send a certificate. If you also want to require it, set
# auth_ssl_require_client_cert=yes in auth section.
#ssl_verify_client_cert = no

# Which field from certificate to use for username. commonName and
# x500UniqueIdentifier are the usual choices. You'll also need to set
# auth_ssl_username_from_cert=yes.
#ssl_cert_username_field = commonName

# DH parameters length to use.
ssl_dh_parameters_length = 4096

# SSL protocols to use
ssl_protocols = !SSLv2

# SSL ciphers to use
ssl_cipher_list = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:+CAMELLIA256:+AES256:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA

# Prefer the server's order of ciphers over client's.
ssl_prefer_server_ciphers = yes

# SSL crypto device to use, for valid values run "openssl engine"
#ssl_crypto_device =
boson@emma:~$ cat /etc/dovecot/conf.d/10-ssl.conf
##
## SSL settings
##

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = yes

# PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
# dropping root privileges, so keep the key file unreadable by anyone but
# root. Included doc/mkcert.sh can be used to easily generate self-signed
# certificate, just make sure to update the domains in dovecot-openssl.cnf
ssl_cert = </etc/ssl/private/mail.pem
ssl_key = </etc/ssl/private/mail.pem

# If key file is password protected, give the password here. Alternatively
# give it when starting dovecot with -p parameter. Since this file is often
# world-readable, you may want to place this setting instead to a different
# root owned 0600 file by using ssl_key_password = <path.
#ssl_key_password =

# PEM encoded trusted certificate authority. Set this only if you intend to use
# ssl_verify_client_cert=yes. The file should contain the CA certificate(s)
# followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem)
#ssl_ca =

# Require that CRL check succeeds for client certificates.
#ssl_require_crl = yes

# Directory and/or file for trusted SSL CA certificates. These are used only
# when Dovecot needs to act as an SSL client (e.g. imapc backend). The
# directory is usually /etc/ssl/certs in Debian-based systems and the file is
# /etc/pki/tls/cert.pem in RedHat-based systems.
#ssl_client_ca_dir =
#ssl_client_ca_file =

# Request client to send a certificate. If you also want to require it, set
# auth_ssl_require_client_cert=yes in auth section.
#ssl_verify_client_cert = no

# Which field from certificate to use for username. commonName and
# x500UniqueIdentifier are the usual choices. You'll also need to set
# auth_ssl_username_from_cert=yes.
#ssl_cert_username_field = commonName

# DH parameters length to use.
ssl_dh_parameters_length = 4096

# SSL protocols to use
ssl_protocols = !SSLv2

# SSL ciphers to use
ssl_cipher_list = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:+CAMELLIA256:+AES256:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA

# Prefer the server's order of ciphers over client's.
ssl_prefer_server_ciphers = yes

# SSL crypto device to use, for valid values run "openssl engine"
#ssl_crypto_device =

So when I now try to connect with TLS/SSL for example with mutt as follows:

mutt <email address hidden>@localhost

Dovecot crashes and in mail.log and mail.err the following appears:

Dec 29 02:33:22 mailer dovecot: imap-login: Error: SSL: Stacked error: error:0608308E:digital envelope routines:EVP_PKEY_get1_EC_KEY:expecting a ec key
Dec 29 02:33:22 mailer dovecot: imap-login: Fatal: Can't load ssl_cert: error:0906D06C:PEM routines:PEM_read_bio:no start line
Dec 29 02:33:22 mailer dovecot: master: Error: service(imap-login): command startup failed, throttling for 2 secs

I really don't understand what this trys to tell me. I googled the thing but could not find very much, I think it's not a configuration issue. The same certificate and key works with Postfix so it should be valid.

Does someone know how to solve this?

Best Regards