CentOS – Can’t SSH into VM in OpenStack

In Openstack, I can spawn ubuntu and fedora images and ssh into them.
But when I am trying the same with Centos image (6.5 or 7), then my key is refused (or even ignored) and I am proposed to use enter a password.
It seems that ssh key injection doesn't work with Centos images (I tried different ones).

Any idea where I should investigate?

Here is the output of ssh command with verbose option:

debug1: Connection established.
debug1: identity file /c/Users/bastien/.ssh/id_rsa_bastien type 1
debug1: identity file /c/Users/bastien/.ssh/id_rsa_bastien-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000000
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<3072<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: RSA 2b:6c:50:28:d0:1c:8b:50:c6:53:75:6f:bb:aa:6e:a7
debug1: Host '37.59.242.188' is known and matches the RSA host key.
debug1: Found key in /c/Users/bastien/.ssh/known_hosts:13
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /c/Users/bastien/.ssh/id_rsa_bastien
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: password