import "github.com/kasperlewau/pwpem"

pem := []byte("-----BEGIN PRIVATE KEY-----\nbase64encodedprivatekey....")
pass := []byte("password")

e, err := pwpem.Encrypt(pem, pass)
fmt.Println(string(e)); // "-----BEGIN PRIVATE KEY-----\nProc-Type: 4,ENCRYPTED\nDEK-Info: AES-256....."

d, err := pwpem.Decrypt(e, pass)
fmt.Println(string(d)); // "-----BEGIN PRIVATE KEY-----\nbase64encodedprivatekey....")