1、将aps_developer_identity.cer转换成aps_developer_identity.pem格式
openssl x509 -in aps_developer_identity.cer -inform DER -out aps_developer_identity.pem -outform PEM
2、将p12格式的私钥转换成pem
openssl pkcs12 -nocerts -out Push_Noenc.pem -in Push.p12
原文：http://www.cnblogs.com/frounk/p/5177915.html