+++ /dev/null
-// 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 openpgp
-
-import (
- "crypto/rsa"
- "io"
- "time"
-
- "golang.org/x/crypto/openpgp/armor"
- "golang.org/x/crypto/openpgp/errors"
- "golang.org/x/crypto/openpgp/packet"
-)
-
-// PublicKeyType is the armor type for a PGP public key.
-var PublicKeyType = "PGP PUBLIC KEY BLOCK"
-
-// PrivateKeyType is the armor type for a PGP private key.
-var PrivateKeyType = "PGP PRIVATE KEY BLOCK"
-
-// An Entity represents the components of an OpenPGP key: a primary public key
-// (which must be a signing key), one or more identities claimed by that key,
-// and zero or more subkeys, which may be encryption keys.
-type Entity struct {
- PrimaryKey *packet.PublicKey
- PrivateKey *packet.PrivateKey
- Identities map[string]*Identity // indexed by Identity.Name
- Revocations []*packet.Signature
- Subkeys []Subkey
-}
-
-// An Identity represents an identity claimed by an Entity and zero or more
-// assertions by other entities about that claim.
-type Identity struct {
- Name string // by convention, has the form "Full Name (comment) <email@example.com>"
- UserId *packet.UserId
- SelfSignature *packet.Signature
- Signatures []*packet.Signature
-}
-
-// A Subkey is an additional public key in an Entity. Subkeys can be used for
-// encryption.
-type Subkey struct {
- PublicKey *packet.PublicKey
- PrivateKey *packet.PrivateKey
- Sig *packet.Signature
-}
-
-// A Key identifies a specific public key in an Entity. This is either the
-// Entity's primary key or a subkey.
-type Key struct {
- Entity *Entity
- PublicKey *packet.PublicKey
- PrivateKey *packet.PrivateKey
- SelfSignature *packet.Signature
-}
-
-// A KeyRing provides access to public and private keys.
-type KeyRing interface {
- // KeysById returns the set of keys that have the given key id.
- KeysById(id uint64) []Key
- // KeysByIdAndUsage returns the set of keys with the given id
- // that also meet the key usage given by requiredUsage.
- // The requiredUsage is expressed as the bitwise-OR of
- // packet.KeyFlag* values.
- KeysByIdUsage(id uint64, requiredUsage byte) []Key
- // DecryptionKeys returns all private keys that are valid for
- // decryption.
- DecryptionKeys() []Key
-}
-
-// primaryIdentity returns the Identity marked as primary or the first identity
-// if none are so marked.
-func (e *Entity) primaryIdentity() *Identity {
- var firstIdentity *Identity
- for _, ident := range e.Identities {
- if firstIdentity == nil {
- firstIdentity = ident
- }
- if ident.SelfSignature.IsPrimaryId != nil && *ident.SelfSignature.IsPrimaryId {
- return ident
- }
- }
- return firstIdentity
-}
-
-// encryptionKey returns the best candidate Key for encrypting a message to the
-// given Entity.
-func (e *Entity) encryptionKey(now time.Time) (Key, bool) {
- candidateSubkey := -1
-
- // Iterate the keys to find the newest key
- var maxTime time.Time
- for i, subkey := range e.Subkeys {
- if subkey.Sig.FlagsValid &&
- subkey.Sig.FlagEncryptCommunications &&
- subkey.PublicKey.PubKeyAlgo.CanEncrypt() &&
- !subkey.Sig.KeyExpired(now) &&
- (maxTime.IsZero() || subkey.Sig.CreationTime.After(maxTime)) {
- candidateSubkey = i
- maxTime = subkey.Sig.CreationTime
- }
- }
-
- if candidateSubkey != -1 {
- subkey := e.Subkeys[candidateSubkey]
- return Key{e, subkey.PublicKey, subkey.PrivateKey, subkey.Sig}, true
- }
-
- // If we don't have any candidate subkeys for encryption and
- // the primary key doesn't have any usage metadata then we
- // assume that the primary key is ok. Or, if the primary key is
- // marked as ok to encrypt to, then we can obviously use it.
- i := e.primaryIdentity()
- if !i.SelfSignature.FlagsValid || i.SelfSignature.FlagEncryptCommunications &&
- e.PrimaryKey.PubKeyAlgo.CanEncrypt() &&
- !i.SelfSignature.KeyExpired(now) {
- return Key{e, e.PrimaryKey, e.PrivateKey, i.SelfSignature}, true
- }
-
- // This Entity appears to be signing only.
- return Key{}, false
-}
-
-// signingKey return the best candidate Key for signing a message with this
-// Entity.
-func (e *Entity) signingKey(now time.Time) (Key, bool) {
- candidateSubkey := -1
-
- for i, subkey := range e.Subkeys {
- if subkey.Sig.FlagsValid &&
- subkey.Sig.FlagSign &&
- subkey.PublicKey.PubKeyAlgo.CanSign() &&
- !subkey.Sig.KeyExpired(now) {
- candidateSubkey = i
- break
- }
- }
-
- if candidateSubkey != -1 {
- subkey := e.Subkeys[candidateSubkey]
- return Key{e, subkey.PublicKey, subkey.PrivateKey, subkey.Sig}, true
- }
-
- // If we have no candidate subkey then we assume that it's ok to sign
- // with the primary key.
- i := e.primaryIdentity()
- if !i.SelfSignature.FlagsValid || i.SelfSignature.FlagSign &&
- !i.SelfSignature.KeyExpired(now) {
- return Key{e, e.PrimaryKey, e.PrivateKey, i.SelfSignature}, true
- }
-
- return Key{}, false
-}
-
-// An EntityList contains one or more Entities.
-type EntityList []*Entity
-
-// KeysById returns the set of keys that have the given key id.
-func (el EntityList) KeysById(id uint64) (keys []Key) {
- for _, e := range el {
- if e.PrimaryKey.KeyId == id {
- var selfSig *packet.Signature
- for _, ident := range e.Identities {
- if selfSig == nil {
- selfSig = ident.SelfSignature
- } else if ident.SelfSignature.IsPrimaryId != nil && *ident.SelfSignature.IsPrimaryId {
- selfSig = ident.SelfSignature
- break
- }
- }
- keys = append(keys, Key{e, e.PrimaryKey, e.PrivateKey, selfSig})
- }
-
- for _, subKey := range e.Subkeys {
- if subKey.PublicKey.KeyId == id {
- keys = append(keys, Key{e, subKey.PublicKey, subKey.PrivateKey, subKey.Sig})
- }
- }
- }
- return
-}
-
-// KeysByIdAndUsage returns the set of keys with the given id that also meet
-// the key usage given by requiredUsage. The requiredUsage is expressed as
-// the bitwise-OR of packet.KeyFlag* values.
-func (el EntityList) KeysByIdUsage(id uint64, requiredUsage byte) (keys []Key) {
- for _, key := range el.KeysById(id) {
- if len(key.Entity.Revocations) > 0 {
- continue
- }
-
- if key.SelfSignature.RevocationReason != nil {
- continue
- }
-
- if key.SelfSignature.FlagsValid && requiredUsage != 0 {
- var usage byte
- if key.SelfSignature.FlagCertify {
- usage |= packet.KeyFlagCertify
- }
- if key.SelfSignature.FlagSign {
- usage |= packet.KeyFlagSign
- }
- if key.SelfSignature.FlagEncryptCommunications {
- usage |= packet.KeyFlagEncryptCommunications
- }
- if key.SelfSignature.FlagEncryptStorage {
- usage |= packet.KeyFlagEncryptStorage
- }
- if usage&requiredUsage != requiredUsage {
- continue
- }
- }
-
- keys = append(keys, key)
- }
- return
-}
-
-// DecryptionKeys returns all private keys that are valid for decryption.
-func (el EntityList) DecryptionKeys() (keys []Key) {
- for _, e := range el {
- for _, subKey := range e.Subkeys {
- if subKey.PrivateKey != nil && (!subKey.Sig.FlagsValid || subKey.Sig.FlagEncryptStorage || subKey.Sig.FlagEncryptCommunications) {
- keys = append(keys, Key{e, subKey.PublicKey, subKey.PrivateKey, subKey.Sig})
- }
- }
- }
- return
-}
-
-// ReadArmoredKeyRing reads one or more public/private keys from an armor keyring file.
-func ReadArmoredKeyRing(r io.Reader) (EntityList, error) {
- block, err := armor.Decode(r)
- if err == io.EOF {
- return nil, errors.InvalidArgumentError("no armored data found")
- }
- if err != nil {
- return nil, err
- }
- if block.Type != PublicKeyType && block.Type != PrivateKeyType {
- return nil, errors.InvalidArgumentError("expected public or private key block, got: " + block.Type)
- }
-
- return ReadKeyRing(block.Body)
-}
-
-// ReadKeyRing reads one or more public/private keys. Unsupported keys are
-// ignored as long as at least a single valid key is found.
-func ReadKeyRing(r io.Reader) (el EntityList, err error) {
- packets := packet.NewReader(r)
- var lastUnsupportedError error
-
- for {
- var e *Entity
- e, err = ReadEntity(packets)
- if err != nil {
- // TODO: warn about skipped unsupported/unreadable keys
- if _, ok := err.(errors.UnsupportedError); ok {
- lastUnsupportedError = err
- err = readToNextPublicKey(packets)
- } else if _, ok := err.(errors.StructuralError); ok {
- // Skip unreadable, badly-formatted keys
- lastUnsupportedError = err
- err = readToNextPublicKey(packets)
- }
- if err == io.EOF {
- err = nil
- break
- }
- if err != nil {
- el = nil
- break
- }
- } else {
- el = append(el, e)
- }
- }
-
- if len(el) == 0 && err == nil {
- err = lastUnsupportedError
- }
- return
-}
-
-// readToNextPublicKey reads packets until the start of the entity and leaves
-// the first packet of the new entity in the Reader.
-func readToNextPublicKey(packets *packet.Reader) (err error) {
- var p packet.Packet
- for {
- p, err = packets.Next()
- if err == io.EOF {
- return
- } else if err != nil {
- if _, ok := err.(errors.UnsupportedError); ok {
- err = nil
- continue
- }
- return
- }
-
- if pk, ok := p.(*packet.PublicKey); ok && !pk.IsSubkey {
- packets.Unread(p)
- return
- }
- }
-}
-
-// ReadEntity reads an entity (public key, identities, subkeys etc) from the
-// given Reader.
-func ReadEntity(packets *packet.Reader) (*Entity, error) {
- e := new(Entity)
- e.Identities = make(map[string]*Identity)
-
- p, err := packets.Next()
- if err != nil {
- return nil, err
- }
-
- var ok bool
- if e.PrimaryKey, ok = p.(*packet.PublicKey); !ok {
- if e.PrivateKey, ok = p.(*packet.PrivateKey); !ok {
- packets.Unread(p)
- return nil, errors.StructuralError("first packet was not a public/private key")
- } else {
- e.PrimaryKey = &e.PrivateKey.PublicKey
- }
- }
-
- if !e.PrimaryKey.PubKeyAlgo.CanSign() {
- return nil, errors.StructuralError("primary key cannot be used for signatures")
- }
-
- var current *Identity
- var revocations []*packet.Signature
-EachPacket:
- for {
- p, err := packets.Next()
- if err == io.EOF {
- break
- } else if err != nil {
- return nil, err
- }
-
- switch pkt := p.(type) {
- case *packet.UserId:
- current = new(Identity)
- current.Name = pkt.Id
- current.UserId = pkt
- e.Identities[pkt.Id] = current
-
- for {
- p, err = packets.Next()
- if err == io.EOF {
- return nil, io.ErrUnexpectedEOF
- } else if err != nil {
- return nil, err
- }
-
- sig, ok := p.(*packet.Signature)
- if !ok {
- return nil, errors.StructuralError("user ID packet not followed by self-signature")
- }
-
- if (sig.SigType == packet.SigTypePositiveCert || sig.SigType == packet.SigTypeGenericCert) && sig.IssuerKeyId != nil && *sig.IssuerKeyId == e.PrimaryKey.KeyId {
- if err = e.PrimaryKey.VerifyUserIdSignature(pkt.Id, e.PrimaryKey, sig); err != nil {
- return nil, errors.StructuralError("user ID self-signature invalid: " + err.Error())
- }
- current.SelfSignature = sig
- break
- }
- current.Signatures = append(current.Signatures, sig)
- }
- case *packet.Signature:
- if pkt.SigType == packet.SigTypeKeyRevocation {
- revocations = append(revocations, pkt)
- } else if pkt.SigType == packet.SigTypeDirectSignature {
- // TODO: RFC4880 5.2.1 permits signatures
- // directly on keys (eg. to bind additional
- // revocation keys).
- } else if current == nil {
- return nil, errors.StructuralError("signature packet found before user id packet")
- } else {
- current.Signatures = append(current.Signatures, pkt)
- }
- case *packet.PrivateKey:
- if pkt.IsSubkey == false {
- packets.Unread(p)
- break EachPacket
- }
- err = addSubkey(e, packets, &pkt.PublicKey, pkt)
- if err != nil {
- return nil, err
- }
- case *packet.PublicKey:
- if pkt.IsSubkey == false {
- packets.Unread(p)
- break EachPacket
- }
- err = addSubkey(e, packets, pkt, nil)
- if err != nil {
- return nil, err
- }
- default:
- // we ignore unknown packets
- }
- }
-
- if len(e.Identities) == 0 {
- return nil, errors.StructuralError("entity without any identities")
- }
-
- for _, revocation := range revocations {
- err = e.PrimaryKey.VerifyRevocationSignature(revocation)
- if err == nil {
- e.Revocations = append(e.Revocations, revocation)
- } else {
- // TODO: RFC 4880 5.2.3.15 defines revocation keys.
- return nil, errors.StructuralError("revocation signature signed by alternate key")
- }
- }
-
- return e, nil
-}
-
-func addSubkey(e *Entity, packets *packet.Reader, pub *packet.PublicKey, priv *packet.PrivateKey) error {
- var subKey Subkey
- subKey.PublicKey = pub
- subKey.PrivateKey = priv
- p, err := packets.Next()
- if err == io.EOF {
- return io.ErrUnexpectedEOF
- }
- if err != nil {
- return errors.StructuralError("subkey signature invalid: " + err.Error())
- }
- var ok bool
- subKey.Sig, ok = p.(*packet.Signature)
- if !ok {
- return errors.StructuralError("subkey packet not followed by signature")
- }
- if subKey.Sig.SigType != packet.SigTypeSubkeyBinding && subKey.Sig.SigType != packet.SigTypeSubkeyRevocation {
- return errors.StructuralError("subkey signature with wrong type")
- }
- err = e.PrimaryKey.VerifyKeySignature(subKey.PublicKey, subKey.Sig)
- if err != nil {
- return errors.StructuralError("subkey signature invalid: " + err.Error())
- }
- e.Subkeys = append(e.Subkeys, subKey)
- return nil
-}
-
-const defaultRSAKeyBits = 2048
-
-// NewEntity returns an Entity that contains a fresh RSA/RSA keypair with a
-// single identity composed of the given full name, comment and email, any of
-// which may be empty but must not contain any of "()<>\x00".
-// If config is nil, sensible defaults will be used.
-func NewEntity(name, comment, email string, config *packet.Config) (*Entity, error) {
- currentTime := config.Now()
-
- bits := defaultRSAKeyBits
- if config != nil && config.RSABits != 0 {
- bits = config.RSABits
- }
-
- uid := packet.NewUserId(name, comment, email)
- if uid == nil {
- return nil, errors.InvalidArgumentError("user id field contained invalid characters")
- }
- signingPriv, err := rsa.GenerateKey(config.Random(), bits)
- if err != nil {
- return nil, err
- }
- encryptingPriv, err := rsa.GenerateKey(config.Random(), bits)
- if err != nil {
- return nil, err
- }
-
- e := &Entity{
- PrimaryKey: packet.NewRSAPublicKey(currentTime, &signingPriv.PublicKey),
- PrivateKey: packet.NewRSAPrivateKey(currentTime, signingPriv),
- Identities: make(map[string]*Identity),
- }
- isPrimaryId := true
- e.Identities[uid.Id] = &Identity{
- Name: uid.Name,
- UserId: uid,
- SelfSignature: &packet.Signature{
- CreationTime: currentTime,
- SigType: packet.SigTypePositiveCert,
- PubKeyAlgo: packet.PubKeyAlgoRSA,
- Hash: config.Hash(),
- IsPrimaryId: &isPrimaryId,
- FlagsValid: true,
- FlagSign: true,
- FlagCertify: true,
- IssuerKeyId: &e.PrimaryKey.KeyId,
- },
- }
-
- // If the user passes in a DefaultHash via packet.Config,
- // set the PreferredHash for the SelfSignature.
- if config != nil && config.DefaultHash != 0 {
- e.Identities[uid.Id].SelfSignature.PreferredHash = []uint8{hashToHashId(config.DefaultHash)}
- }
-
- e.Subkeys = make([]Subkey, 1)
- e.Subkeys[0] = Subkey{
- PublicKey: packet.NewRSAPublicKey(currentTime, &encryptingPriv.PublicKey),
- PrivateKey: packet.NewRSAPrivateKey(currentTime, encryptingPriv),
- Sig: &packet.Signature{
- CreationTime: currentTime,
- SigType: packet.SigTypeSubkeyBinding,
- PubKeyAlgo: packet.PubKeyAlgoRSA,
- Hash: config.Hash(),
- FlagsValid: true,
- FlagEncryptStorage: true,
- FlagEncryptCommunications: true,
- IssuerKeyId: &e.PrimaryKey.KeyId,
- },
- }
- e.Subkeys[0].PublicKey.IsSubkey = true
- e.Subkeys[0].PrivateKey.IsSubkey = true
-
- return e, nil
-}
-
-// SerializePrivate serializes an Entity, including private key material, to
-// the given Writer. For now, it must only be used on an Entity returned from
-// NewEntity.
-// If config is nil, sensible defaults will be used.
-func (e *Entity) SerializePrivate(w io.Writer, config *packet.Config) (err error) {
- err = e.PrivateKey.Serialize(w)
- if err != nil {
- return
- }
- for _, ident := range e.Identities {
- err = ident.UserId.Serialize(w)
- if err != nil {
- return
- }
- err = ident.SelfSignature.SignUserId(ident.UserId.Id, e.PrimaryKey, e.PrivateKey, config)
- if err != nil {
- return
- }
- err = ident.SelfSignature.Serialize(w)
- if err != nil {
- return
- }
- }
- for _, subkey := range e.Subkeys {
- err = subkey.PrivateKey.Serialize(w)
- if err != nil {
- return
- }
- err = subkey.Sig.SignKey(subkey.PublicKey, e.PrivateKey, config)
- if err != nil {
- return
- }
- err = subkey.Sig.Serialize(w)
- if err != nil {
- return
- }
- }
- return nil
-}
-
-// Serialize writes the public part of the given Entity to w. (No private
-// key material will be output).
-func (e *Entity) Serialize(w io.Writer) error {
- err := e.PrimaryKey.Serialize(w)
- if err != nil {
- return err
- }
- for _, ident := range e.Identities {
- err = ident.UserId.Serialize(w)
- if err != nil {
- return err
- }
- err = ident.SelfSignature.Serialize(w)
- if err != nil {
- return err
- }
- for _, sig := range ident.Signatures {
- err = sig.Serialize(w)
- if err != nil {
- return err
- }
- }
- }
- for _, subkey := range e.Subkeys {
- err = subkey.PublicKey.Serialize(w)
- if err != nil {
- return err
- }
- err = subkey.Sig.Serialize(w)
- if err != nil {
- return err
- }
- }
- return nil
-}
-
-// SignIdentity adds a signature to e, from signer, attesting that identity is
-// associated with e. The provided identity must already be an element of
-// e.Identities and the private key of signer must have been decrypted if
-// necessary.
-// If config is nil, sensible defaults will be used.
-func (e *Entity) SignIdentity(identity string, signer *Entity, config *packet.Config) error {
- if signer.PrivateKey == nil {
- return errors.InvalidArgumentError("signing Entity must have a private key")
- }
- if signer.PrivateKey.Encrypted {
- return errors.InvalidArgumentError("signing Entity's private key must be decrypted")
- }
- ident, ok := e.Identities[identity]
- if !ok {
- return errors.InvalidArgumentError("given identity string not found in Entity")
- }
-
- sig := &packet.Signature{
- SigType: packet.SigTypeGenericCert,
- PubKeyAlgo: signer.PrivateKey.PubKeyAlgo,
- Hash: config.Hash(),
- CreationTime: config.Now(),
- IssuerKeyId: &signer.PrivateKey.KeyId,
- }
- if err := sig.SignUserId(identity, e.PrimaryKey, signer.PrivateKey, config); err != nil {
- return err
- }
- ident.Signatures = append(ident.Signatures, sig)
- return nil
-}
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