go-network[13]-rsa

/* GenRSAKeys
 */

package main

import (
    "crypto/rand"
    "crypto/rsa"
    "crypto/x509"
    "encoding/gob"
    "encoding/pem"
    "fmt"
    "os"
)

func main() {
    reader := rand.Reader
    bitSize := 512
    key, err := rsa.GenerateKey(reader, bitSize)
    checkError(err)

    fmt.Println("Private key primes", key.Primes[0].String(), key.Primes[1].String())
    fmt.Println("Private key exponent", key.D.String())

    publicKey := key.PublicKey
    fmt.Println("Public key modulus", publicKey.N.String())
    fmt.Println("Public key exponent", publicKey.E)

    saveGobKey("private.key", key)
    saveGobKey("public.key", publicKey)

    savePEMKey("private.pem", key)
}

func saveGobKey(fileName string, key interface{}) {
    outFile, err := os.Create(fileName)
    checkError(err)
    encoder := gob.NewEncoder(outFile)
    err = encoder.Encode(key)
    checkError(err)
    outFile.Close()
}

func savePEMKey(fileName string, key *rsa.PrivateKey) {

    outFile, err := os.Create(fileName)
    checkError(err)

    var privateKey = &pem.Block{Type: "RSA PRIVATE KEY",
        Bytes: x509.MarshalPKCS1PrivateKey(key)}

    pem.Encode(outFile, privateKey)

    outFile.Close()
}

func checkError(err error) {
    if err != nil {
        fmt.Println("Fatal error ", err.Error())
        os.Exit(1)
    }
}

/* LoadRSAKeys
 */

package main

import (
    "crypto/rsa"
    "encoding/gob"
    "fmt"
    "os"
)

func main() {
    var key rsa.PrivateKey
    loadKey("private.key", &key)

    fmt.Println("Private key primes", key.Primes[0].String(), key.Primes[1].String())
    fmt.Println("Private key exponent", key.D.String())

    var publicKey rsa.PublicKey
    loadKey("public.key", &publicKey)

    fmt.Println("Public key modulus", publicKey.N.String())
    fmt.Println("Public key exponent", publicKey.E)
}

func loadKey(fileName string, key interface{}) {
    inFile, err := os.Open(fileName)
    checkError(err)
    decoder := gob.NewDecoder(inFile)
    err = decoder.Decode(key)
    checkError(err)
    inFile.Close()
}

func checkError(err error) {
    if err != nil {
        fmt.Println("Fatal error ", err.Error())
        os.Exit(1)
    }
}