How to convert data type ECDSA private key in Go

Question

I am using the ecdsa.GenerateKey method to generate a private key pair in Go. I would like to send my private key(priva) with socket programming and can read other private key(privb) from other program.

priva, _ := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)

_, err = connection.Write([]byte(priva))
buffer := make([]byte, 1024)
mLen, err := connection.Read(buffer)
if err != nil {
    fmt.Println("Error reading:", err.Error())
}
privb := buffer[:mLen]

There is my code to send data and read data to/from other program, but i can't send my private key(priva) because it can't change the types. How to fixed, or is there a recommended way to send/read the data ?

score 1 · Answer 1 · answered Apr 15 '22 at 03:07

The *ecdsa.PrivateKey cannot be directly sent over the network. It must be marshalled into a []byte first.

You can use x509.MarshalECPrivateKey to marshal into DER format, and x509.ParseECPrivateKey to unmarshal.

For example:

package main

import (
    "crypto/ecdsa"
    "crypto/elliptic"
    "crypto/rand"
    "crypto/x509"
    "fmt"
)

func main() {
    priv, _ := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)

    derBuf, _ := x509.MarshalECPrivateKey(priv)

    // Transfer []byte to new location.

    privCopy, _ := x509.ParseECPrivateKey(derBuf)

    fmt.Println(priv.Equal(privCopy))
    /// Output: true
}

Note: this example doesn't provide any additional security around the private key. You may want to ensure the transfer/protocol handling is appropriate for your security needs.

How to convert data type ECDSA private key in Go

1 Answers1