79 lines
2.3 KiB
Go
79 lines
2.3 KiB
Go
/*
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SSHSecure - a program to harden OpenSSH from defaults
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Copyright (C) 2020 Brent Saner
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package sshkeys
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import (
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"crypto/aes"
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"crypto/cipher"
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"errors"
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// `golang.org/x/crypto/ssh/internal/bcrypt_pbkdf` Golang doesn't let you import "internal" libs. Fine. Lame language.
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"github.com/dchest/bcrypt_pbkdf"
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)
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func (k *EncryptedSSHKeyV1) setCrypt() error {
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// First we need the KDF (Key Derivation Function).
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if err := k.setKDF(); err != nil {
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return err
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}
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// And then we set the actual cipher (the thing that does the encrypting).
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if err := k.setCipher(); err != nil {
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return err
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}
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return nil
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}
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func (k *EncryptedSSHKeyV1) setCipher() error {
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var err error
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switch k.CipherName {
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case CipherAes256Ctr:
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if k.Crypt.Cipher, err = aes.NewCipher(k.Crypt.PrivateKey); err != nil {
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return err
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} else {
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k.Crypt.Stream = cipher.NewCTR(k.Crypt.Cipher, k.Crypt.CryptSalt)
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// Can then be used as k.Crypt.Stream.XORKeyStream(dst []byte, src []byte)
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}
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default:
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return errors.New("could not find Cipher")
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}
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return nil
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}
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func (k *EncryptedSSHKeyV1) setKDF() error {
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var err error
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// Upstream only currently supports bcrypt_pbkdf ("bcrypt").
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// This should always eval to true, but is here for future planning in case other KDF are implemented.
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switch k.KDFName {
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case KdfBcrypt:
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if k.Crypt.CryptKey, err = bcrypt_pbkdf.Key(k.Passphrase,
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k.KDFOpts.Salt,
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int(k.KDFOpts.Rounds),
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kdfKeyLen+len(k.KDFOpts.Salt),
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); err != nil {
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return err
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} else {
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k.Crypt.PrivateKey = k.Crypt.CryptKey[0:kdfSplit]
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k.Crypt.CryptSalt = k.Crypt.CryptKey[kdfSplit:]
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}
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default:
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return errors.New("could not find KDF")
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}
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return nil
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}
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