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Admin Guide > Configuration > Managing ICE Gateway > Running an ICE Telephony Gateway using Non-TLS/SRTP > Enabling TLS/SRTP > Generating a Self-Signed Certificate File (.pem)
Generating a Self-Signed Certificate File (.pem)
Either a 3rd party certificate generated by a certificate authority, or a self-signed certificate, is required to establish a TLS connection between CUCM and the ICE Telephony Gateway. In the following example a self-signed certificate is generated using the OpenSSL command line tool.
To generate a self-signed .pem file
1. Open the OpenSSL command line tool.
2. Enter the following command:
openssl req -x509 -newkey rsa:4096 -keyout icegwkey.pem -out icegw.pem -days 365 -nodes
3. From the resulting output, enter the required certificate information, see the example below.
A blue screen with white text Description automatically generated
*Country Name
*State or Province Name
*Locality Name
*Organization Name
*Common Name: Enter the IP address of the ICE Telephony Gateway. That will be the destination address for the SIP Trunk created later in this process.
*Email Address
4. Enter the following command:
openssl
Two PEM files are generated:
*icegwkey.pem
*icegw.pem
5. Proceed to the next procedure (Uploading the Certificate File to CUCM).