Refactor api (#6)
* Refactor library, remove duplicates * Rebuild structure to use Messages and Signature models * Use PGPSplitMessage * Remove signature model * Various fixes * Add helpers with tests * Fixes, add some docs, add tests * Add attachment helpers * Add helpers Symmetric encryption * Edit docs + examples * Rename kr to keyRing * Various fixes for documentation * Edit JSON handling functions, add decrypt keyring via token * Add proposal changes doc * Fix CI * Drop *Message functions, join CleartextMessage and BinaryMessage * Change canonicalization and trimming only to text signatures * Add cleartextsignature, detach signature from message model, move helpers * Documentation, remove optional parameters * Move verification to separate model * Don't return message in VerifyDetached * Update table of contents in readme * Appease golint * Run go fmt * Rename Encrypt/DecryptMessageWithPassword to ..WithToken These functions shouldn't be used with user-provided passwords, as they don't do any key-stretching. * Change key generation usernames
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wussler
GitHub
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34 changed files with 2573 additions and 1478 deletions
255
crypto/keyring_message.go
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255
crypto/keyring_message.go
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@ -0,0 +1,255 @@
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package crypto
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import (
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"bytes"
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"crypto"
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"errors"
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"io"
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"io/ioutil"
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"math"
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"time"
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"golang.org/x/crypto/openpgp"
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pgpErrors "golang.org/x/crypto/openpgp/errors"
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"golang.org/x/crypto/openpgp/packet"
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"github.com/ProtonMail/gopenpgp/constants"
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"github.com/ProtonMail/gopenpgp/internal"
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)
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// Encrypt encrypts a PlainMessage, outputs a PGPMessage.
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// If an unlocked private key is also provided it will also sign the message.
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// message : The plaintext input as a PlainMessage
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// privateKey : (optional) an unlocked private keyring to include signature in the message
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func (keyRing *KeyRing) Encrypt(message *PlainMessage, privateKey *KeyRing) (*PGPMessage, error) {
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encrypted, err := asymmetricEncrypt(message.GetBinary(), keyRing, privateKey, true)
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if err != nil {
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return nil, err
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}
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return NewPGPMessage(encrypted), nil
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}
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// Decrypt decrypts encrypted string using pgp keys, returning a PlainMessage
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// message : The encrypted input as a PGPMessage
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// verifyKey : Public key for signature verification (optional)
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// verifyTime : Time at verification (necessary only if verifyKey is not nil)
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func (keyRing *KeyRing) Decrypt(
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message *PGPMessage, verifyKey *KeyRing, verifyTime int64,
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) (*PlainMessage, *Verification, error) {
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decrypted, verifyStatus, err := asymmetricDecrypt(message.NewReader(), keyRing, verifyKey, verifyTime)
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if err != nil {
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return nil, nil, err
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}
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return NewPlainMessage(decrypted), newVerification(verifyStatus), nil
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}
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// SignDetached generates and returns a PGPSignature for a given PlainMessage
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func (keyRing *KeyRing) SignDetached(message *PlainMessage) (*PGPSignature, error) {
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signEntity, err := keyRing.GetSigningEntity()
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if err != nil {
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return nil, err
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}
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config := &packet.Config{DefaultHash: crypto.SHA512, Time: pgp.getTimeGenerator()}
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var outBuf bytes.Buffer
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//sign bin
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if err := openpgp.DetachSign(&outBuf, signEntity, message.NewReader(), config); err != nil {
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return nil, err
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}
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return NewPGPSignature(outBuf.Bytes()), nil
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}
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// VerifyDetached verifies a PlainMessage with embedded a PGPSignature
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// and returns a Verification with the filled Verified field.
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func (keyRing *KeyRing) VerifyDetached(
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message *PlainMessage, signature *PGPSignature, verifyTime int64,
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) (*Verification, error) {
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var err error
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verifyVal, err := verifySignature(
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keyRing.GetEntities(),
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message.NewReader(),
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signature.GetBinary(),
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verifyTime,
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)
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return newVerification(verifyVal), err
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}
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// ------ INTERNAL FUNCTIONS -------
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// Core for encryption+signature functions
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func asymmetricEncrypt(data []byte, publicKey *KeyRing, privateKey *KeyRing, isBinary bool) ([]byte, error) {
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var outBuf bytes.Buffer
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var encryptWriter io.WriteCloser
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var signEntity *openpgp.Entity
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var err error
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if privateKey != nil && len(privateKey.entities) > 0 {
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var err error
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signEntity, err = privateKey.GetSigningEntity()
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if err != nil {
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return nil, err
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}
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}
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config := &packet.Config{DefaultCipher: packet.CipherAES256, Time: pgp.getTimeGenerator()}
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hints := &openpgp.FileHints{
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IsBinary: isBinary,
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FileName: "",
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}
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if isBinary {
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encryptWriter, err = openpgp.Encrypt(&outBuf, publicKey.entities, signEntity, hints, config)
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} else {
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encryptWriter, err = openpgp.EncryptText(&outBuf, publicKey.entities, signEntity, hints, config)
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}
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if err != nil {
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return nil, err
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}
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_, err = encryptWriter.Write(data)
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encryptWriter.Close()
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if err != nil {
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return nil, err
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}
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return outBuf.Bytes(), nil
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}
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// Core for decryption+verification functions
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func asymmetricDecrypt(
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encryptedIO io.Reader, privateKey *KeyRing, verifyKey *KeyRing, verifyTime int64,
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) (plaintext []byte, verified int, err error) {
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privKeyEntries := privateKey.GetEntities()
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var additionalEntries openpgp.EntityList
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if verifyKey != nil {
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additionalEntries = verifyKey.GetEntities()
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}
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if additionalEntries != nil {
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privKeyEntries = append(privKeyEntries, additionalEntries...)
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}
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config := &packet.Config{Time: pgp.getTimeGenerator()}
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messageDetails, err := openpgp.ReadMessage(encryptedIO, privKeyEntries, nil, config)
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if err != nil {
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return nil, constants.SIGNATURE_NOT_SIGNED, err
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}
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if verifyKey != nil {
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processSignatureExpiration(messageDetails, verifyTime)
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}
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body, err := ioutil.ReadAll(messageDetails.UnverifiedBody)
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if err != nil {
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return nil, constants.SIGNATURE_NOT_SIGNED, err
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}
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if verifyKey != nil {
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verifyStatus, verifyError := verifyDetailsSignature(messageDetails, verifyKey)
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if verifyStatus == constants.SIGNATURE_FAILED {
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return nil, verifyStatus, errors.New(verifyError)
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}
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return body, verifyStatus, nil
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}
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return body, constants.SIGNATURE_NOT_SIGNED, nil
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}
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// processSignatureExpiration handles signature time verification manually, so we can add a margin to the
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// creationTime check.
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func processSignatureExpiration(md *openpgp.MessageDetails, verifyTime int64) {
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if md.SignatureError == pgpErrors.ErrSignatureExpired {
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if verifyTime > 0 {
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created := md.Signature.CreationTime.Unix()
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expires := int64(math.MaxInt64)
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if md.Signature.SigLifetimeSecs != nil {
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expires = int64(*md.Signature.SigLifetimeSecs) + created
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}
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if created-internal.CreationTimeOffset <= verifyTime && verifyTime <= expires {
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md.SignatureError = nil
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}
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} else {
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// verifyTime = 0: time check disabled, everything is okay
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md.SignatureError = nil
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}
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}
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}
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// Verify signature from message details
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func verifyDetailsSignature(md *openpgp.MessageDetails, verifierKey *KeyRing) (int, string) {
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if md.IsSigned {
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if md.SignedBy != nil {
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if len(verifierKey.entities) > 0 {
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matches := verifierKey.entities.KeysById(md.SignedByKeyId)
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if len(matches) > 0 {
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if md.SignatureError == nil {
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return constants.SIGNATURE_OK, ""
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}
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return constants.SIGNATURE_FAILED, md.SignatureError.Error()
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}
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} else {
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return constants.SIGNATURE_NO_VERIFIER, ""
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}
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} else {
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return constants.SIGNATURE_NO_VERIFIER, ""
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}
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}
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return constants.SIGNATURE_NOT_SIGNED, ""
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}
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// verifySignature verifies if a signature is valid with the entity list
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func verifySignature(
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pubKeyEntries openpgp.EntityList, origText io.Reader, signature []byte, verifyTime int64) (int, error) {
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config := &packet.Config{}
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if verifyTime == 0 {
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config.Time = func() time.Time {
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return time.Unix(0, 0)
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}
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} else {
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config.Time = func() time.Time {
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return time.Unix(verifyTime+internal.CreationTimeOffset, 0)
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}
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}
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signatureReader := bytes.NewReader(signature)
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signer, err := openpgp.CheckDetachedSignature(pubKeyEntries, origText, signatureReader, config)
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if err == pgpErrors.ErrSignatureExpired && signer != nil {
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if verifyTime > 0 { // if verifyTime = 0: time check disabled, everything is okay
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// Maybe the creation time offset pushed it over the edge
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// Retry with the actual verification time
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config.Time = func() time.Time {
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return time.Unix(verifyTime, 0)
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}
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_, err = signatureReader.Seek(0, io.SeekStart)
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if err != nil {
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return constants.SIGNATURE_FAILED, err
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}
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signer, err = openpgp.CheckDetachedSignature(pubKeyEntries, origText, signatureReader, config)
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if err != nil {
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return constants.SIGNATURE_FAILED, err
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}
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}
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}
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if signer == nil {
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return constants.SIGNATURE_FAILED, errors.New("gopenpgp: signer is empty")
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}
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// if signer.PrimaryKey.KeyId != signed.PrimaryKey.KeyId {
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// // t.Errorf("wrong signer got:%x want:%x", signer.PrimaryKey.KeyId, 0)
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// return false, errors.New("signer is nil")
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// }
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return constants.SIGNATURE_OK, nil
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}
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