agola/internal/util/ssh.go

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2019-02-21 16:58:25 +00:00
// Copyright 2019 Sorint.lab
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied
// See the License for the specific language governing permissions and
// limitations under the License.
package util
import (
"bytes"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"errors"
"golang.org/x/crypto/ssh"
)
// GenSSHKeyPair generate an ssh keypair in rsa format, returning the private
// key (in pem encoding) and the public key (in the OpenSSH base64 format)
func GenSSHKeyPair(bits int) ([]byte, []byte, error) {
privateKey, err := rsa.GenerateKey(rand.Reader, bits)
if err != nil {
return nil, nil, err
}
err = privateKey.Validate()
if err != nil {
return nil, nil, err
}
privateKeyPEM := &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(privateKey)}
var privateBuf bytes.Buffer
if err := pem.Encode(&privateBuf, privateKeyPEM); err != nil {
return nil, nil, errors.New("failed to pem encode private key")
}
pub, err := ssh.NewPublicKey(&privateKey.PublicKey)
if err != nil {
return nil, nil, errors.New("failed to generate public key")
}
// remove trailing \n returned by ssh.MarshalAuthorizedKey
return privateBuf.Bytes(), bytes.TrimSuffix(ssh.MarshalAuthorizedKey(pub), []byte("\n")), nil
}
// ExtraxtPublicKey extracts the public key from a ssh private key in pem format
func ExtractPublicKey(privateKeyPEM []byte) ([]byte, error) {
block, _ := pem.Decode(privateKeyPEM)
if block == nil || block.Type != "RSA PRIVATE KEY" {
return nil, errors.New("failed to decode PEM block containing rsa private key")
}
privateKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
if err != nil {
return nil, errors.New("failed to parse rsa private key")
}
err = privateKey.Validate()
if err != nil {
return nil, errors.New("failed to validate rsa private key")
}
pub, err := ssh.NewPublicKey(&privateKey.PublicKey)
if err != nil {
return nil, errors.New("failed to generate public key")
}
// remove trailing \n returned by ssh.MarshalAuthorizedKey
return bytes.TrimSuffix(ssh.MarshalAuthorizedKey(pub), []byte("\n")), nil
}