looping

Convert the CER file downloaded from app's APN (at developer.apple.com), to PEM
openssl x509 -in aps_development.cer -inform DER -out aps_development.pem -outform PEM

Convert the P12 file created with Keychain Access to PEM
openssl pkcs12 -nocerts -in Certificates.p12 -out Certificates.pem

Create a new, GOOD, P12 file
openssl pkcs12 -export -inkey Certificates.pem -in aps_development.pem -out GOOD_Certificates.p12

https://www.raywenderlich.com/32960/apple-push-notification-services-in-ios-6-tutorial-part-1