Save and load crypto/rsa PrivateKey to and from the disk

Question

I\'m using crypto/rsa, and trying to find a way to properly save and load a key. Is there a correct way to create a []byte from an rsa.P

Answer 1

Since the public key part of your question wasn't answered and I just ran into the same problem and solved it, here it is:

Note the & in front of the Argument to MarshalPKIXPublicKey

Priv := rsa.GenerateKey(rand.Reader, 4096)

pubASN1, err := x509.MarshalPKIXPublicKey(&Priv.PublicKey)
if err != nil {
    // do something about it
}

pubBytes := pem.EncodeToMemory(&pem.Block{
    Type:  "RSA PUBLIC KEY",
    Bytes: pubASN1,
})

ioutil.WriteFile("key.pub", pubBytes, 0644)

---

Relevant reads:

• MarshalPKIXPublicKey(pub interface{}) ([]byte, error) godoc
• EncodeToMemory(b *Block) []byte godoc
• Block godoc

PS: MarshalPKIXPublicKey also accepts ECDSA keys, ajust the pem header appropriately.