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user.go
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user.go
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package openpgp
import (
"io"
"time"
"github.com/ProtonMail/go-crypto/v2/openpgp/errors"
"github.com/ProtonMail/go-crypto/v2/openpgp/packet"
)
// An Identity represents an identity claimed by an Entity and zero or more
// assertions by other entities about that claim.
type Identity struct {
Primary *Entity
Name string // by convention, has the form "Full Name (comment) <email@example.com>"
UserId *packet.UserId
SelfCertifications []*packet.VerifiableSignature
OtherCertifications []*packet.VerifiableSignature
Revocations []*packet.VerifiableSignature
}
func readUser(e *Entity, packets *packet.Reader, pkt *packet.UserId) error {
identity := Identity{
Primary: e,
Name: pkt.Id,
UserId: pkt,
}
for {
p, err := packets.NextWithUnsupported()
if err == io.EOF {
break
} else if err != nil {
return err
}
unsupportedPacket, unsupported := p.(*packet.UnsupportedPacket)
sigCandidate := p
if unsupported {
sigCandidate = unsupportedPacket.IncompletePacket
}
sig, ok := sigCandidate.(*packet.Signature)
if !ok {
// sigCandidate is a not a signature packet, reset and stop.
packets.Unread(p)
break
} else if unsupported {
// sigCandidate is a signature packet but unsupported.
continue
}
if sig.SigType != packet.SigTypeGenericCert &&
sig.SigType != packet.SigTypePersonaCert &&
sig.SigType != packet.SigTypeCasualCert &&
sig.SigType != packet.SigTypePositiveCert &&
sig.SigType != packet.SigTypeCertificationRevocation {
// Ignore signatures with wrong type
continue
}
if sig.CheckKeyIdOrFingerprint(e.PrimaryKey) {
if sig.SigType == packet.SigTypeCertificationRevocation {
identity.Revocations = append(identity.Revocations, packet.NewVerifiableSig(sig))
} else {
identity.SelfCertifications = append(identity.SelfCertifications, packet.NewVerifiableSig(sig))
}
e.Identities[pkt.Id] = &identity
} else {
identity.OtherCertifications = append(identity.OtherCertifications, packet.NewVerifiableSig(sig))
}
}
return nil
}
func (i *Identity) Serialize(w io.Writer) error {
if err := i.UserId.Serialize(w); err != nil {
return err
}
for _, sig := range i.Revocations {
if err := sig.Packet.Serialize(w); err != nil {
return err
}
}
for _, sig := range i.SelfCertifications {
if err := sig.Packet.Serialize(w); err != nil {
return err
}
}
for _, sig := range i.OtherCertifications {
if err := sig.Packet.Serialize(w); err != nil {
return err
}
}
return nil
}
// Verify checks if the user-id is valid by checking:
// - that a valid self-certification exists and is not expired
// - that user-id has not been revoked at the given point in time
// If date is zero (i.e., date.IsZero() == true) the time checks are not performed.
func (i *Identity) Verify(date time.Time) (selfSignature *packet.Signature, err error) {
if selfSignature, err = i.LatestValidSelfCertification(date); err != nil {
return
}
if i.Revoked(selfSignature, date) {
return nil, errors.StructuralError("user-id is revoked")
}
return
}
// Revoked returns whether the identity has been revoked by a self-signature.
// Note that third-party revocation signatures are not supported.
func (i *Identity) Revoked(selfCertification *packet.Signature, date time.Time) bool {
// Verify revocations first
for _, revocation := range i.Revocations {
if selfCertification == nil || // if there is not selfCertification verify revocation
selfCertification.IssuerKeyId == nil ||
revocation.Packet.IssuerKeyId == nil ||
(*selfCertification.IssuerKeyId == *revocation.Packet.IssuerKeyId) { // check matching key id
if revocation.Valid == nil {
// Verify revocation signature (not verified yet).
err := i.Primary.PrimaryKey.VerifyUserIdSignature(i.Name, i.Primary.PrimaryKey, revocation.Packet)
valid := err == nil
revocation.Valid = &valid
}
if *revocation.Valid &&
(date.IsZero() || // Check revocation not expired
!revocation.Packet.SigExpired(date)) &&
(selfCertification == nil || // Check that revocation is not older than the selfCertification
selfCertification.CreationTime.Unix() <= revocation.Packet.CreationTime.Unix()) {
return true
}
}
}
return false
}
func (i *Identity) ReSign(config *packet.Config) error {
selectedSig, err := i.LatestValidSelfCertification(config.Now())
if err != nil {
return err
}
if err = selectedSig.SignUserId(
i.UserId.Id,
i.Primary.PrimaryKey,
i.Primary.PrivateKey,
config,
); 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 (ident *Identity) SignIdentity(signer *Entity, config *packet.Config) error {
certificationKey, ok := signer.CertificationKey(config.Now(), config)
if !ok {
return errors.InvalidArgumentError("no valid certification key found")
}
if certificationKey.PrivateKey.Encrypted {
return errors.InvalidArgumentError("signing Entity's private key must be decrypted")
}
if !ok {
return errors.InvalidArgumentError("given identity string not found in Entity")
}
sig := createSignaturePacket(certificationKey.PublicKey, packet.SigTypeGenericCert, config)
signingUserID := config.SigningUserId()
if signingUserID != "" {
if _, ok := signer.Identities[signingUserID]; !ok {
return errors.InvalidArgumentError("signer identity string not found in signer Entity")
}
sig.SignerUserId = &signingUserID
}
if err := sig.SignUserId(ident.Name, ident.Primary.PrimaryKey, certificationKey.PrivateKey, config); err != nil {
return err
}
ident.OtherCertifications = append(ident.OtherCertifications, packet.NewVerifiableSig(sig))
return nil
}
// LatestValidSelfCertification returns the latest valid self-signature of this user-id
// that is not newer than the provided date.
// Does not consider signatures that are expired.
// If date is zero (i.e., date.IsZero() == true) the expiration checks are not performed.
// Returns a StructuralError if no valid self-certification is found.
func (i *Identity) LatestValidSelfCertification(date time.Time) (selectedSig *packet.Signature, err error) {
for sigIdx := len(i.SelfCertifications) - 1; sigIdx >= 0; sigIdx-- {
sig := i.SelfCertifications[sigIdx]
if (date.IsZero() || date.Unix() >= sig.Packet.CreationTime.Unix()) && // SelfCertification must be older than date
(selectedSig == nil || selectedSig.CreationTime.Unix() < sig.Packet.CreationTime.Unix()) { // Newer ones are preferred
if sig.Valid == nil {
// Verify revocation signature (not verified yet).
err = i.Primary.PrimaryKey.VerifyUserIdSignature(i.Name, i.Primary.PrimaryKey, sig.Packet)
valid := err == nil
sig.Valid = &valid
}
if *sig.Valid && (date.IsZero() || !sig.Packet.SigExpired(date)) {
selectedSig = sig.Packet
}
}
}
if selectedSig == nil {
return nil, errors.StructuralError("no valid certification signature found for identity")
}
return
}