[HELP]: "not expected size" error on "keys init"

I’m trying to set up TLS & SRTP. I have my various keyfiles in place, but when I run “keys init” at the asterisk console and enter my password I get “NOTICE[18453]: : : Key ‘ca’ is not expected size”

Curiously, if I enter a wrong password I get a different error code, “WARNING[18453]: : : Key load PRIVATE ‘ca’ failed”

I’ve checked the permissions (including SELinux context) on the key files.

System info:

CentOS 6.7

Asterisk 12.8.2 (installed from asterisk.org repo)

Keys generated using the ast_tls_cert script from the 12.8.2 source ("./ast_tls_cert -C MYPU.BLIC.IPH.ERE -O “MYORGNAMEHERE” -d /var/lib/asterisk/keys")

libsrtp 1.4.4-4