87 lines
2.5 KiB
Go
87 lines
2.5 KiB
Go
package crypto
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import (
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"bytes"
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"io/ioutil"
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"net/mail"
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"net/textproto"
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"strings"
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gomime "github.com/ProtonMail/go-mime"
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"github.com/pkg/errors"
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"golang.org/x/crypto/openpgp"
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"golang.org/x/crypto/openpgp/packet"
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)
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// MIMECallbacks defines callback methods to process a MIME message.
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type MIMECallbacks interface {
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OnBody(body string, mimetype string)
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OnAttachment(headers string, data []byte)
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// Encrypted headers can be in an attachment and thus be placed at the end of the mime structure.
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OnEncryptedHeaders(headers string)
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OnVerified(verified int)
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OnError(err error)
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}
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// DecryptMIMEMessage decrypts a MIME message.
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func (keyRing *KeyRing) DecryptMIMEMessage(
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message *PGPMessage, verifyKey *KeyRing, callbacks MIMECallbacks, verifyTime int64,
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) {
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decryptedMessage, err := keyRing.Decrypt(message, verifyKey, verifyTime)
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if err != nil {
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callbacks.OnError(err)
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return
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}
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body, attachments, attachmentHeaders, err := parseMIME(string(decryptedMessage.GetBinary()), verifyKey)
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if err != nil {
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callbacks.OnError(err)
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return
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}
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bodyContent, bodyMimeType := body.GetBody()
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callbacks.OnBody(bodyContent, bodyMimeType)
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for i := 0; i < len(attachments); i++ {
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callbacks.OnAttachment(attachmentHeaders[i], []byte(attachments[i]))
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}
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callbacks.OnEncryptedHeaders("")
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}
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// ----- INTERNAL FUNCTIONS -----
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func parseMIME(
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mimeBody string, verifierKey *KeyRing,
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) (*gomime.BodyCollector, []string, []string, error) {
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mm, err := mail.ReadMessage(strings.NewReader(mimeBody))
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if err != nil {
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return nil, nil, nil, errors.Wrap(err, "gopenpgp: error in reading message")
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}
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config := &packet.Config{DefaultCipher: packet.CipherAES256, Time: getTimeGenerator()}
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h := textproto.MIMEHeader(mm.Header)
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mmBodyData, err := ioutil.ReadAll(mm.Body)
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if err != nil {
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return nil, nil, nil, errors.Wrap(err, "gopenpgp: error in reading message body data")
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}
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printAccepter := gomime.NewMIMEPrinter()
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bodyCollector := gomime.NewBodyCollector(printAccepter)
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attachmentsCollector := gomime.NewAttachmentsCollector(bodyCollector)
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mimeVisitor := gomime.NewMimeVisitor(attachmentsCollector)
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var pgpKering openpgp.KeyRing
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if verifierKey != nil {
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pgpKering = verifierKey.entities
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}
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signatureCollector := newSignatureCollector(mimeVisitor, pgpKering, config)
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err = gomime.VisitAll(bytes.NewReader(mmBodyData), h, signatureCollector)
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if err == nil && verifierKey != nil {
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err = signatureCollector.verified
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}
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return bodyCollector,
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attachmentsCollector.GetAttachments(),
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attachmentsCollector.GetAttHeaders(),
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err
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}
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