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package main
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"fmt"
"golang.org/x/crypto/ssh"
)
type key interface{}
type keyfunc func(int) (key, ssh.PublicKey, error)
var (
keytypes = map[string]keyfunc{
"rsa": generateRSAKey,
"ecdsa": generateECDSAKey,
}
)
func generateRSAKey(bits int) (key, ssh.PublicKey, error) {
k, err := rsa.GenerateKey(rand.Reader, bits)
if err != nil {
return nil, nil, err
}
pub, err := ssh.NewPublicKey(&k.PublicKey)
if err != nil {
return nil, nil, err
}
return k, pub, nil
}
func generateECDSAKey(bits int) (key, ssh.PublicKey, error) {
var curve elliptic.Curve
switch bits {
case 256:
curve = elliptic.P256()
case 384:
curve = elliptic.P384()
case 521:
curve = elliptic.P521()
default:
return nil, nil, fmt.Errorf("Unsupported key size. Valid sizes are '256', '384', '521'")
}
k, err := ecdsa.GenerateKey(curve, rand.Reader)
if err != nil {
return nil, nil, err
}
pub, err := ssh.NewPublicKey(&k.PublicKey)
if err != nil {
return nil, nil, err
}
return k, pub, nil
}
func generateKey(keytype string, bits int) (key, ssh.PublicKey, error) {
f, ok := keytypes[keytype]
if !ok {
var valid []string
for k := range keytypes {
valid = append(valid, k)
}
return nil, nil, fmt.Errorf("Unsupported key type %s. Valid choices are %s", keytype, valid)
}
return f(bits)
}
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