woodpecker/vendor/code.google.com/p/go.crypto/ssh/certs.go
2015-09-29 18:21:17 -07:00

378 lines
8.9 KiB
Go

// Copyright 2012 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 (
"time"
)
// These constants from [PROTOCOL.certkeys] represent the algorithm names
// for certificate types supported by this package.
const (
CertAlgoRSAv01 = "ssh-rsa-cert-v01@openssh.com"
CertAlgoDSAv01 = "ssh-dss-cert-v01@openssh.com"
CertAlgoECDSA256v01 = "ecdsa-sha2-nistp256-cert-v01@openssh.com"
CertAlgoECDSA384v01 = "ecdsa-sha2-nistp384-cert-v01@openssh.com"
CertAlgoECDSA521v01 = "ecdsa-sha2-nistp521-cert-v01@openssh.com"
)
// Certificate types are used to specify whether a certificate is for identification
// of a user or a host. Current identities are defined in [PROTOCOL.certkeys].
const (
UserCert = 1
HostCert = 2
)
type signature struct {
Format string
Blob []byte
}
type tuple struct {
Name string
Data string
}
const (
maxUint64 = 1<<64 - 1
maxInt64 = 1<<63 - 1
)
// CertTime represents an unsigned 64-bit time value in seconds starting from
// UNIX epoch. We use CertTime instead of time.Time in order to properly handle
// the "infinite" time value ^0, which would become negative when expressed as
// an int64.
type CertTime uint64
func (ct CertTime) Time() time.Time {
if ct > maxInt64 {
return time.Unix(maxInt64, 0)
}
return time.Unix(int64(ct), 0)
}
func (ct CertTime) IsInfinite() bool {
return ct == maxUint64
}
// An OpenSSHCertV01 represents an OpenSSH certificate as defined in
// [PROTOCOL.certkeys]?rev=1.8.
type OpenSSHCertV01 struct {
Nonce []byte
Key PublicKey
Serial uint64
Type uint32
KeyId string
ValidPrincipals []string
ValidAfter, ValidBefore CertTime
CriticalOptions []tuple
Extensions []tuple
Reserved []byte
SignatureKey PublicKey
Signature *signature
}
// validateOpenSSHCertV01Signature uses the cert's SignatureKey to verify that
// the cert's Signature.Blob is the result of signing the cert bytes starting
// from the algorithm string and going up to and including the SignatureKey.
func validateOpenSSHCertV01Signature(cert *OpenSSHCertV01) bool {
return cert.SignatureKey.Verify(cert.BytesForSigning(), cert.Signature.Blob)
}
var certAlgoNames = map[string]string{
KeyAlgoRSA: CertAlgoRSAv01,
KeyAlgoDSA: CertAlgoDSAv01,
KeyAlgoECDSA256: CertAlgoECDSA256v01,
KeyAlgoECDSA384: CertAlgoECDSA384v01,
KeyAlgoECDSA521: CertAlgoECDSA521v01,
}
// certToPrivAlgo returns the underlying algorithm for a certificate algorithm.
// Panics if a non-certificate algorithm is passed.
func certToPrivAlgo(algo string) string {
for privAlgo, pubAlgo := range certAlgoNames {
if pubAlgo == algo {
return privAlgo
}
}
panic("unknown cert algorithm")
}
func (cert *OpenSSHCertV01) marshal(includeAlgo, includeSig bool) []byte {
algoName := cert.PublicKeyAlgo()
pubKey := cert.Key.Marshal()
sigKey := MarshalPublicKey(cert.SignatureKey)
var length int
if includeAlgo {
length += stringLength(len(algoName))
}
length += stringLength(len(cert.Nonce))
length += len(pubKey)
length += 8 // Length of Serial
length += 4 // Length of Type
length += stringLength(len(cert.KeyId))
length += lengthPrefixedNameListLength(cert.ValidPrincipals)
length += 8 // Length of ValidAfter
length += 8 // Length of ValidBefore
length += tupleListLength(cert.CriticalOptions)
length += tupleListLength(cert.Extensions)
length += stringLength(len(cert.Reserved))
length += stringLength(len(sigKey))
if includeSig {
length += signatureLength(cert.Signature)
}
ret := make([]byte, length)
r := ret
if includeAlgo {
r = marshalString(r, []byte(algoName))
}
r = marshalString(r, cert.Nonce)
copy(r, pubKey)
r = r[len(pubKey):]
r = marshalUint64(r, cert.Serial)
r = marshalUint32(r, cert.Type)
r = marshalString(r, []byte(cert.KeyId))
r = marshalLengthPrefixedNameList(r, cert.ValidPrincipals)
r = marshalUint64(r, uint64(cert.ValidAfter))
r = marshalUint64(r, uint64(cert.ValidBefore))
r = marshalTupleList(r, cert.CriticalOptions)
r = marshalTupleList(r, cert.Extensions)
r = marshalString(r, cert.Reserved)
r = marshalString(r, sigKey)
if includeSig {
r = marshalSignature(r, cert.Signature)
}
if len(r) > 0 {
panic("ssh: internal error, marshaling certificate did not fill the entire buffer")
}
return ret
}
func (cert *OpenSSHCertV01) BytesForSigning() []byte {
return cert.marshal(true, false)
}
func (cert *OpenSSHCertV01) Marshal() []byte {
return cert.marshal(false, true)
}
func (c *OpenSSHCertV01) PublicKeyAlgo() string {
algo, ok := certAlgoNames[c.Key.PublicKeyAlgo()]
if !ok {
panic("unknown cert key type")
}
return algo
}
func (c *OpenSSHCertV01) PrivateKeyAlgo() string {
return c.Key.PrivateKeyAlgo()
}
func (c *OpenSSHCertV01) Verify(data []byte, sig []byte) bool {
return c.Key.Verify(data, sig)
}
func parseOpenSSHCertV01(in []byte, algo string) (out *OpenSSHCertV01, rest []byte, ok bool) {
cert := new(OpenSSHCertV01)
if cert.Nonce, in, ok = parseString(in); !ok {
return
}
privAlgo := certToPrivAlgo(algo)
cert.Key, in, ok = parsePubKey(in, privAlgo)
if !ok {
return
}
// We test PublicKeyAlgo to make sure we don't use some weird sub-cert.
if cert.Key.PublicKeyAlgo() != privAlgo {
ok = false
return
}
if cert.Serial, in, ok = parseUint64(in); !ok {
return
}
if cert.Type, in, ok = parseUint32(in); !ok {
return
}
keyId, in, ok := parseString(in)
if !ok {
return
}
cert.KeyId = string(keyId)
if cert.ValidPrincipals, in, ok = parseLengthPrefixedNameList(in); !ok {
return
}
va, in, ok := parseUint64(in)
if !ok {
return
}
cert.ValidAfter = CertTime(va)
vb, in, ok := parseUint64(in)
if !ok {
return
}
cert.ValidBefore = CertTime(vb)
if cert.CriticalOptions, in, ok = parseTupleList(in); !ok {
return
}
if cert.Extensions, in, ok = parseTupleList(in); !ok {
return
}
if cert.Reserved, in, ok = parseString(in); !ok {
return
}
sigKey, in, ok := parseString(in)
if !ok {
return
}
if cert.SignatureKey, _, ok = ParsePublicKey(sigKey); !ok {
return
}
if cert.Signature, in, ok = parseSignature(in); !ok {
return
}
ok = true
return cert, in, ok
}
func lengthPrefixedNameListLength(namelist []string) int {
length := 4 // length prefix for list
for _, name := range namelist {
length += 4 // length prefix for name
length += len(name)
}
return length
}
func marshalLengthPrefixedNameList(to []byte, namelist []string) []byte {
length := uint32(lengthPrefixedNameListLength(namelist) - 4)
to = marshalUint32(to, length)
for _, name := range namelist {
to = marshalString(to, []byte(name))
}
return to
}
func parseLengthPrefixedNameList(in []byte) (out []string, rest []byte, ok bool) {
list, rest, ok := parseString(in)
if !ok {
return
}
for len(list) > 0 {
var next []byte
if next, list, ok = parseString(list); !ok {
return nil, nil, false
}
out = append(out, string(next))
}
ok = true
return
}
func tupleListLength(tupleList []tuple) int {
length := 4 // length prefix for list
for _, t := range tupleList {
length += 4 // length prefix for t.Name
length += len(t.Name)
length += 4 // length prefix for t.Data
length += len(t.Data)
}
return length
}
func marshalTupleList(to []byte, tuplelist []tuple) []byte {
length := uint32(tupleListLength(tuplelist) - 4)
to = marshalUint32(to, length)
for _, t := range tuplelist {
to = marshalString(to, []byte(t.Name))
to = marshalString(to, []byte(t.Data))
}
return to
}
func parseTupleList(in []byte) (out []tuple, rest []byte, ok bool) {
list, rest, ok := parseString(in)
if !ok {
return
}
for len(list) > 0 {
var name, data []byte
var ok bool
name, list, ok = parseString(list)
if !ok {
return nil, nil, false
}
data, list, ok = parseString(list)
if !ok {
return nil, nil, false
}
out = append(out, tuple{string(name), string(data)})
}
ok = true
return
}
func signatureLength(sig *signature) int {
length := 4 // length prefix for signature
length += stringLength(len(sig.Format))
length += stringLength(len(sig.Blob))
return length
}
func marshalSignature(to []byte, sig *signature) []byte {
length := uint32(signatureLength(sig) - 4)
to = marshalUint32(to, length)
to = marshalString(to, []byte(sig.Format))
to = marshalString(to, sig.Blob)
return to
}
func parseSignatureBody(in []byte) (out *signature, rest []byte, ok bool) {
var format []byte
if format, in, ok = parseString(in); !ok {
return
}
out = &signature{
Format: string(format),
}
if out.Blob, in, ok = parseString(in); !ok {
return
}
return out, in, ok
}
func parseSignature(in []byte) (out *signature, rest []byte, ok bool) {
var sigBytes []byte
if sigBytes, rest, ok = parseString(in); !ok {
return
}
out, sigBytes, ok = parseSignatureBody(sigBytes)
if !ok || len(sigBytes) > 0 {
return nil, nil, false
}
return
}