Certificate upgrade and conversion

# Install OpenSSL (Ubuntu/Debian)
apt update && apt install openssl

# Extract private key
openssl pkcs12 -in newmyapp.p12 -nodes -nocerts -out myappkey.pem

# Extract original certificate
openssl pkcs12 -in newmyapp.p12 -nokeys -out old-cert.pem

# Generate a new self-signed certificate
openssl req -new -x509 \
  -key myappkey.pem \
  -out new-cert.pem \
  -days 9125 \
  -subj "CN=Organization name or domain name, OU=Department or branch name, O=Organization, L=City, ST=State or province, C=Your country"

# Export to PKCS12 format
openssl pkcs12 -export \
  -in new-cert.pem \
  -inkey myappkey.pem \
  -out newmyapp-renewed.p12 \
  -name myappkey \
  -passout pass: Your password