mirror of
https://github.com/woodpecker-ci/woodpecker.git
synced 2024-07-15 18:18:21 +00:00
101 lines
2.9 KiB
Go
101 lines
2.9 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package ssh
|
|
|
|
import (
|
|
"crypto/aes"
|
|
"crypto/cipher"
|
|
"crypto/rc4"
|
|
)
|
|
|
|
// streamDump is used to dump the initial keystream for stream ciphers. It is a
|
|
// a write-only buffer, and not intended for reading so do not require a mutex.
|
|
var streamDump [512]byte
|
|
|
|
// noneCipher implements cipher.Stream and provides no encryption. It is used
|
|
// by the transport before the first key-exchange.
|
|
type noneCipher struct{}
|
|
|
|
func (c noneCipher) XORKeyStream(dst, src []byte) {
|
|
copy(dst, src)
|
|
}
|
|
|
|
func newAESCTR(key, iv []byte) (cipher.Stream, error) {
|
|
c, err := aes.NewCipher(key)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return cipher.NewCTR(c, iv), nil
|
|
}
|
|
|
|
func newRC4(key, iv []byte) (cipher.Stream, error) {
|
|
return rc4.NewCipher(key)
|
|
}
|
|
|
|
type cipherMode struct {
|
|
keySize int
|
|
ivSize int
|
|
skip int
|
|
createFunc func(key, iv []byte) (cipher.Stream, error)
|
|
}
|
|
|
|
func (c *cipherMode) createCipher(key, iv []byte) (cipher.Stream, error) {
|
|
if len(key) < c.keySize {
|
|
panic("ssh: key length too small for cipher")
|
|
}
|
|
if len(iv) < c.ivSize {
|
|
panic("ssh: iv too small for cipher")
|
|
}
|
|
|
|
stream, err := c.createFunc(key[:c.keySize], iv[:c.ivSize])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
for remainingToDump := c.skip; remainingToDump > 0; {
|
|
dumpThisTime := remainingToDump
|
|
if dumpThisTime > len(streamDump) {
|
|
dumpThisTime = len(streamDump)
|
|
}
|
|
stream.XORKeyStream(streamDump[:dumpThisTime], streamDump[:dumpThisTime])
|
|
remainingToDump -= dumpThisTime
|
|
}
|
|
|
|
return stream, nil
|
|
}
|
|
|
|
// Specifies a default set of ciphers and a preference order. This is based on
|
|
// OpenSSH's default client preference order, minus algorithms that are not
|
|
// implemented.
|
|
var DefaultCipherOrder = []string{
|
|
"aes128-ctr", "aes192-ctr", "aes256-ctr",
|
|
"arcfour256", "arcfour128",
|
|
}
|
|
|
|
// cipherModes documents properties of supported ciphers. Ciphers not included
|
|
// are not supported and will not be negotiated, even if explicitly requested in
|
|
// ClientConfig.Crypto.Ciphers.
|
|
var cipherModes = map[string]*cipherMode{
|
|
// Ciphers from RFC4344, which introduced many CTR-based ciphers. Algorithms
|
|
// are defined in the order specified in the RFC.
|
|
"aes128-ctr": {16, aes.BlockSize, 0, newAESCTR},
|
|
"aes192-ctr": {24, aes.BlockSize, 0, newAESCTR},
|
|
"aes256-ctr": {32, aes.BlockSize, 0, newAESCTR},
|
|
|
|
// Ciphers from RFC4345, which introduces security-improved arcfour ciphers.
|
|
// They are defined in the order specified in the RFC.
|
|
"arcfour128": {16, 0, 1536, newRC4},
|
|
"arcfour256": {32, 0, 1536, newRC4},
|
|
}
|
|
|
|
// defaultKeyExchangeOrder specifies a default set of key exchange algorithms
|
|
// with preferences.
|
|
var defaultKeyExchangeOrder = []string{
|
|
// P384 and P521 are not constant-time yet, but since we don't
|
|
// reuse ephemeral keys, using them for ECDH should be OK.
|
|
kexAlgoECDH256, kexAlgoECDH384, kexAlgoECDH521,
|
|
kexAlgoDH14SHA1, kexAlgoDH1SHA1,
|
|
}
|