常见问题

现在还忙？您可以随时在应用程序中轻松阅读此帮助，即使在离线状态下。

什么是 Delta Chat？

Delta Chat 是一个新的聊天应用，它通过电子邮件发送消息，并在条件允许情况下使用 Autocrypt 对其进行加密。您不必在任何地方进行注册，在 Delta Chat 中使用您现有的电子邮件帐户即可。

如何找到可以聊天的人？

通过 Delta Chat，您可以发消息到每个现有的电子邮件地址——即使收件人没有使用 Delta Chat 应用。不需要像其他通信软件一样，要收件人安装和您一样的应用。

与其他通信软件相比，Delta Chat 有哪些优势？

哪些消息会在 Delta Chat 中出现？

默认情况下， Delta Chat 会显示所有电子邮件。

通过“设置->聊天与媒体->显示传统电子邮件”，您可以改变这种行为。有三个选项：

如果希望收到我从未发送过消息的人的消息，该怎么办?

Delta Chat 支持图像、视频和其他附件吗？

如何添加账户或在多个账户之间切换？

您可以在Delta Chat 移动和桌面客户端上轻松使用其他账户，只需点击以下任一按钮：

您可能还想了解 如何为多个设备添加账户。

谁会看见我的个人资料图片？

我可以为 Delta Chat 设置签名文本/状态/格言吗？{#signature}

是的， 您可以在“设置 > 个人资料 > 签名文本”下执行此操作。 使用 Delta Chat 的联系人查看您的联系方式时将会看到它。 对其他所有人来说， 它将显示为在您所有消息文本下方的电子邮件签名。

Delta Chat 支持 HTML 电子邮件吗？

是的，收到的 HTML 邮件会有一个 “显示完整消息 “按钮。 发出的邮件始终使用纯文本。

为什么我必须在 Delta Chat 中输入我的电子邮件密码？ 这样安全吗？

与其他电子邮件程序（比如 Thunderbird、K9-Mail 或 Outlook）一样，本程序需要您的密码来允许您通过它发送邮件。当然，密码仅储存在您的设备上，并只会在登录时发送给您的电子邮件提供商（无论如何，您的提供商总是能够访问您的邮件）。

如果您使用具有 OAuth2 支持的电子邮件提供商，例如 gmail.com 或 yandex.ru，则无需在设备上存储密码。在这种情况下，只有访问令牌被使用。

由于 Delta Chat 是开源的，要验证您的凭据是否被安全地处理了，可以检查源代码。我们很高兴能收到使本应用对我们的所有用户更加安全的反馈。

Delta Chat 需要哪些权限？

根据使用的操作系统，系统可能会要求您向本应用授予权限。下面 Delta Chat 使用各类权限进行的操作：

固定、静音、归档是什么意思？

使用这些工具来管理您的聊天，让其井然有序：

要归档或固定一个聊天，可以长按（Android）、使用聊天内部的菜单（Android/桌面版）或者左滑（iOS）； 要静音一个聊天，可以使用聊天内部的菜单（Android/桌面版）或者通过聊天概要（iOS）。

绿色圆点代表什么？

消息定时销毁是如何工作的？{#ephemeralmsgs}

您可以在聊天窗口右上角的聊天设置中通过选择 1 分钟到 5 周之间的时间跨度打开“消息定时销毁”。

Until the setting is turned off again, each chat member’s Delta Chat app takes care of deleting the messages after the selected time span. The time span begins when the receiver first sees the message in Delta Chat. The messages are deleted both in each email account on the server, and in the app itself.

Note that you can rely on disappearing messages only as long as you trust your chat partners; malicious chat partners can take photos, or otherwise save, copy or forward messages before deletion.

Apart from that, if one chat partner uninstalls Delta Chat, the messages will not get deleted from their email account. They will most likely also not be decryptable anymore (as long as they were encrypted in the first place).

如何删除我的账户？

As you use an e-mail account for Delta Chat, how you can delete your account depends on your e-mail provider. We don’t have any control over your e-mail account, so unfortunately we can’t help you with that.

If you want to keep the account, but uninstall Delta Chat, it is recommended to leave any group chat before uninstalling Delta Chat.

群组

创建群组

添加成员到群组

我不小心删除了我自己。

我不想再收到某个群组中的消息了。

显示在发出消息旁边的对勾表示什么？

打开“从服务器删除旧消息”后，会发生什么？

打开“从设备删除旧消息”后，会发生什么？

加密和安全

端到端加密使用了哪些标准 ？

Autocrypt is used for automatically establishing end-to-end encryption with contacts and group chats. Autocrypt uses a limited and secure subset of the OpenPGP standard. End-to-End encrypted messages are marked with a padlock padlock.

Secure-Join protocols are used for establishing chats with guaranteed end-to-end encryption which protects against network attacks and compromised servers. Chats marked with a green checkmark green checkmark guarantee end-to-end encrypted messages.

我如何知道信息是否经过端到端加密？{#whene2e}

All end-to-end encrypted messages carry a padlock:

padlock in bubble

End-to-end encryption is guaranteed if there is a green checkmark next to the chat title:

green checkmark in title

How can I get guaranteed end-to-end encryption and green checkmarks?

Meet your chat partner outside Delta Chat, preferably in person but a second channel like a video chat or a different messenger is fine as well. Perform the following QR show/scan procedure with your chat partner. One of you is the “Inviter”, the other is the “Joiner”.

Inviter side:

Joiner side:

Both Inviter and Joiner:

Wait while Secure-Join network messages are exchanged between both devices.

Congratulations! You now will automatically use guaranteed end-to-end encryption with this contact and both of you can add each other to green-checkmarked groups green checkmark, thereby automatically spreading guaranteed end-to-end encryption among its members.

What does the green checkmark and “guaranteed end-to-end encryption” mean?

Chat titles with green checkmarks green checkmark mean that all messages in the chat will be end-to-end encrypted and can not be read or altered by compromised e-mail servers or Internet providers. Joining green-checkmarked group chats safely spreads everybody’s encryption information (and green checkmarks) in a manner that guarantees end-to-end encryption in the group and among members.

Contact profiles with green checkmarks green checkmark mean that messaging a contact is currently guaranteed to be end-to-end encrypted. Every green-checkmarked contact either did a direct QR-scan with you or was introduced by a another green-checkmarked contact. Introductions happen automatically when adding members to groups. Whoever adds a contact to a green-checkmarked group becomes an introducer to those members who didn’t yet know about the added contact. In a contact profile you can tap on the “Introduced by …” text repeatedly until you get to the one with whom you directly did a QR-scan.

Note that in a contact profile you may see and tap introducers but there is no green checkmark in the profile title. This usually means that the contact “sent a message from another device”.

For more in-depth discussion of “guaranteed end-to-end encryption” please see Secure-Join protocols and specifically read about “Verified Groups”, the technical term of what is called here “green-checkmarked” or “guaranteed end-to-end encrypted” chats.

A contact “sent a message from another device”, what can i do?

Your chat with a contact lost guaranteed end-to-end encryption. The green checkmark was removed for this chat and contact when you see this warning. If you find the sudden drop of guaranteed end-to-end encryption surprising for this contact then don’t accept the warning! Instead check with your contact through a second channel like a video call, other messenger or a phone call, to find out what happened.

If your contact actually caused the drop of guaranteed end-to-end encryption please see the next paragraphs for common reasons and their mitigations. Regardless, all other green-checkmarked chats remain guaranteed end-to-end encrypted even if the contact is a member there.

Your contact is using Delta Chat on a second device (phone or laptop)

If they have another device with a Delta Chat app running, they should remove the account from the new device and add it as a second device as described here. As soon as they message you afterwards, the warning will be gone and guaranteed encryption is established with both devices of your contact.

Your contact reinstalled Delta Chat using their old account login

If they have a backup file, they should remove the account from the new device and rather import the backup file to re-create their account. As soon as they message you afterwards, the warning will be gone and guaranteed encryption is re-established for this contact.

If they don’t have a backup file, it’s best to perform a QR scan with your chat partner to re-establish guaranteed end-to-end encryption.

Your contact sent a mail through a webmail interface or another e-mail app and will get back to using Delta Chat soon again.

If you are sure that the contact sometimes uses webmail, or another mail app lacking end-to-end encryption, then you may accept the warning. As soon as your contact uses Delta Chat again, guaranteed end-to-end encryption will be automatically re-established.

Your contact stopped using Delta Chat entirely

Sometimes remaining in contact is more important than end-to-end encryption. “Transport Layer Encryption” (TLS) may still meaningfully protect the confidentiality of your messages between your device and the e-mail server. But without end-to-end encryption you and your contact are trusting your e-mail server to not read or manipulate your messages, and to not hand them to third parties.

In any case, you can not do much else than accept the warning. Please also remove the contact from any active green-checkmarked group which you can find in “Shared chats” in the Contact profile. This spares your contact from getting “unreadable” messages.

If the contact removed Delta Chat because of buggy or undesirable behaviour, please consider posting to our support forum to help us identify and address common problems. Thanks!

Are attachments (pictures, files, audio etc.) end-to-end encrypted?

Yes.

When we talk about an “end-to-end encrypted message” we always mean a whole message is encrypted, including all the attachments and attachment metadata such as filenames.

Is OpenPGP secure?

Yes, Delta Chat uses a secure subset of OpenPGP and only displays a padlock security indicator on a message if the whole message is properly encrypted and signed. For example, “Detached signatures” are not treated as secure.

OpenPGP is not insecure by itself. Most publically discussed OpenPGP security problems actually stem from bad usability or bad implementations of tools or apps (or both). It is particularly important to distinguish between OpenPGP, the IETF encryption standard, and GnuPG (GPG), a command line tool implementing OpenPGP. Many public critiques of OpenPGP actually discuss GnuPG which Delta Chat has never used. Delta Chat rather uses the OpenPGP Rust implementation rPGP, available as an independent “pgp” package, and security-audited in 2019.

We aim, along with other OpenPGP implementors, to further improve security characteristics by implementing the new IETF OpenPGP Crypto-Refresh which was thankfully adopted in summer 2023.

Did you consider using alternatives to OpenPGP for end-to-end -encryption?

Yes, we are following efforts like MLS or Saltpack but adopting them would mean breaking end-to-end encryption interoperability with all other e-mail apps that typically support OpenPGP encryption. So it would not be a light decision to take and there must be tangible improvements for users.

Delta Chat takes a holistic “usable security” approach and works with a wide range of activist groupings as well as renowned researchers such as TeamUSEC to improve actual user outcomes against security threats. The wire protocol and standard for establishing end-to-end encryption is only one part of “user outcomes”, see also our answers to device-seizure and message-metadata questions.

Is Delta Chat vulnerable to EFAIL?

No, Delta Chat never was vulnerable to EFAIL because its OpenPGP implementation rPGP uses Modification Detection Code when encrypting messages and returns an error if the Modification Detection Code is incorrect.

Delta Chat also never was vulnerable to the “Direct Exfiltration” EFAIL attack because it only decrypts multipart/encrypted messages which contain exactly one encrypted and signed part, as defined by the Autocrypt Level 1 specification.

Is a message exposed in cleartext if end-to-end encryption is not available?

Even if your messages are not guaranteed to be end-to-end encrypted, they are still protected from Internet providers like cell or cable companies. However, your and your recipient’s e-mail providers may read, analyze or even modify your messages, including any attachments, if they are not end-to-end encrypted.

Delta Chat by default uses strict TLS encryption which secures connections between your device and your e-mail provider. All of Delta Chat’s TLS-handling has been independently security audited. Moreover, the connection between your and the recipient’s e-mail provider will typically be transport-encrypted as well. If the involved e-mail servers support MTA-STS then transport encryption will be enforced between e-mail providers in which case Delta Chat communications will never be exposed in cleartext to the Internet even if the message was not end-to-end encrypted.

Note that maintaining guaranteed end-to-end encryption on top of TLS encryption provides pervasive safety between your and the recipient’s devices. Not even your e-mail or Internet provider will be able to read or modify your messages.

How does Delta Chat protect metadata in messages?

Delta Chat protects most message metadata by putting the following information into the end-to-end encrypted part of messages:

E-Mail servers do not get access to this protected metadata but they do see the message date as well as the message size, and, more importantly, the sender and receiver addresses. E-mail servers need receiver addresses to route and deliver messages to recipient’s devices.

How to protect metadata and contacts when a device is seized?

Both for protecting against metadata-collecting e-mail servers as well as against the threat of device seizure we recommend to use a Delta Chat optimized e-mail server instance to create pseudonymous temporary accounts through QR-code scans. Note that Delta Chat apps on all platforms support multiple accounts so you can easily use action-specific “1-week” or “1-month” accounts next to your “main” account with the knowledge that all temporary account data, along with all metadata, will be deleted. Moreover, if a device is seized then contacts using temporary e-mail accounts can not be identified easily, as compared to messengers which reveal phone numbers in chat groups which in turn are often associated with legal identities.

How can i check encryption information?

You may check the end-to-end encryption status manually in the “Encryption” dialog (user profile on Android/iOS or right-click a user’s chat-list item on desktop). Delta Chat shows two fingerprints there. If the same fingerprints appear on your own and your contact’s device, the connection is safe.

How can I check the encryption status of messages?

A little padlock in a message bubble denotes that the message was properly end-to-end encrypted from the given sender. If there is no padlock, the message was not properly end-to-end encrypted most likely because the sender uses an app or webmail interface without support for end-to-end–encryption.

Why do I see unencrypted messages?

If a contact uses a non-Autocrypt e-mail app, all messages involving this contact (in a group or 1:1 chat) will not be end-to-end encrypted, and thus not show a “padlock” with messages. Note that even if your contacts use Delta Chat on their account, they might also use a non-Autocrypt e-mail app on that account which then may cause intermittently unencrypted messages. Replying unencrypted to unencrypted messages is mandated by Autocrypt to prevent unreadable messages on the side of your contacts and their non-Autocrypt e-mail app.

How can i get an end-to-end encrypted chat with a Delta Chat contact who sometimes uses webmail or another non-Autocrypt e-mail app?

If you need a safely end-to-end encrypted chat with a contact who is using their account both with Delta Chat and non-Autocrypt apps (e.g. webmail), it’s best to setup guaranteed end-to-end encryption with them and then create a guaranteed end-to-end encrypted group chat with you two as members. In this group chat all messages will be end-to-end encrypted even if the direct chat between you two has a “… sent a message from another device” warning.

How can I ensure message end-to-end encryption and deletion?

The best way to ensure every message is end-to-end encrypted, and metadata deleted as quickly as possible is using chats with guaranteed end-to-end encryption and turning on disappearing messages.

Guaranteed end-to-end encrypted chats protect against MITM attacks and turning on disappearing messages deletes the messages on the server after a user-configured time.

If you don’t need a longer-lived copy of your messages on the server, you can also turn on “delete messages from server automatically”.

Does Delta Chat support Perfect Forward Secrecy?

No, Delta Chat doesn’t support Perfect Forward Secrecy (PFS). This means that if your Delta Chat private decryption key is leaked, and someone has collected your prior in-transit messages, they will be able to decrypt and read them using the leaked decryption key.

Note, however, that if anyone obtains to your decryption keys, they will typically also be able to obtain your messages, irrespective if Perfect Forward Secrecy is in place or not. The typical real-world situation for leaked decryption keys is device seizure which we discuss in our answer on metadata and device seizure.

It is possible that Delta Chat evolves to support Perfect Forward Secrecy, because OpenPGP is just a container for encrypted messages but encryption key management (and thus key rotation or key “ratcheting”) could be organized in flexible ways. See Seqouia’s PFS prototype for existing experiments in the OpenPGP implementor community.

Is end-to-end encryption of Delta Chat as safe as Signal?

It depends on what is important to you. Delta Chat does not support PFS like Signal does but it provides guaranteed end-to-end encrypted chats that are safe against compromised servers or corrupted networks. Signal and most other PFS-supporting messengers do not provide a practical scheme for protecting chat groups from network attacks which are arguably more worrysome than a potential attacker who seizes your phone and private encryption setup but somehow not your messages, yet has a full record of all past encrypted messages.

In any case, Delta Chat’s end-to-end encryption uses a secure subset of OpenPGP which has been independently security-audited.

我可以重复使用现有的私钥吗？

Yes. The best way is to send an Autocrypt Setup Message from the other e-mail client. Look for something like Start Autocrypt Setup Transfer in the settings of the other client and follow the instructions shown there.

Alternatively, you can import the key manually in “Settings -> Advanced settings -> Import secret keys”. Caution: Make sure the key is not protected by a password, or remove the password beforehand.

If you don’t have a key or don’t even know you would need one - don’t worry: Delta Chat generates keys as needed, you don’t have to hit a button for it.

我无法将现有的 PGP 密钥导入 Delta Chat。

最可能的原因是您的密钥被加密了和/或使用了密码。Delta Chat 不支持这样的密钥。您可以移除密码，之后再尝试导入。如果想保留密码，您 需要创建电子邮件别名来使用 Delta Chat ，这样 Delta Chat 的密钥是绑定到这个电子邮件别名上的

Another common error is having the wrong file ending. Use the ASCII armored format and an .asc file ending.

Delta Chat 支持常见的 OpenPGP 私钥格式。然而，不可能使每种来源的私钥都被完整支持。这不是 Delta Chat 的主要目标。实际上，大多数新用户在使用 Delta Chat 之前根本没有密钥。不过，我们确实在尝试支持尽可能多的私钥来源。

移除私钥密码的操作取决于您用于管理 PGP 密钥的软件。对于 Enigmail，您可以在密钥管理窗口中将密码设为空值。 对于 GnuPG，您可以通过命令行来进行设置。对于其他程序，您应该能在网上找到解决方案。

Was Delta Chat independently audited for security vulnerabilities?

The Delta Chat project underwent four independent security audits in the last years:

多客户端

我能同时在多个设备上使用 Delta Chat 吗?

Yes. Delta Chat 1.36 comes with a new, experimental function for using the same account on different devices:

In contrast to many other messengers, after successful transfer, both devices are completely independent. One device is not needed for the other to work.

故障排除

Manual Transfer

This method is only recommended if “Add Second Device” as described above does not work.

有推出 Delta Chat Web 客户端的计划吗？

“给自己发送副本”设置有什么用处？

向自己发送消息的副本可以确保您在所有设备上收到自己的消息。如果您在使用多台设备时没有打开此设置，那么您将只能看到其他人发过来的消息和您从当前设备发出的消息。

副本会被发送到收件箱，然后会被移动到 DeltaChat 文件夹；它不会被放到“已发送”文件夹里。Delta Chat 从不 将东西上传到已发送文件夹，因为这意味着上传一条消息两次（一次通过 SMTP，一次通过 IMAP 到已发送文件夹）。

给自己发送副本的默认设置是“不”。

为什么我可以选择监视“已发送”文件夹？

监视已发送文件夹的唯一原因是：您在同时使用其他的邮件应用程序（比如 Thunderbird），并且想让邮件分发代理参与聊天对话。

不过，我们推荐使用 Delta Chat 桌面客户端；您可以在 get.delta.chat 下载它。监视“已发送”文件夹的选项是在还没有 Delta Chat 桌面客户端的时候引入的，这个选项可能会在未来消失。

为什么我可以选择不监视 DeltaChat 文件夹？

有些人将 Delta Chat 用作常规电子邮件客户端并希望将收件箱文件夹用于其邮件，而不是使用 DeltaChat 文件夹。如果禁用了“监视 DeltaChat 文件夹”，则还应该禁用“将聊天消息移动到 DeltaChat”。否则，删除消息或多设备设置可能无法正常工作。

webxdc apps

In Delta Chat, you can share webxdc apps, attachments with an .xdc file extension. They can do very different things, and make Delta Chat a truly extendable messenger.

How private are webxdc apps?

Where can I get webxdc apps?

How can I create my own webxdc apps?

实验性功能

We are very grateful for feedback on these features - do you want to share your ideas? Join the Forum to contribute. You may conveniently login via Delta Chat and a QR code scan, another rather stable experiment we run on the side (sic!).

怎样在 Delta Chat 中使用音频/视频通话？

什么是广播列表？怎样使用它们？

如何与聊天伙伴分享位置？

实验性的数据库加密到底保护了什么？

为什么我可以选择只监视 DeltaChat 文件夹？

这是提供给尝试服务器端规则的人的实验性设置。在使用某些电子邮件提供商时，您可以将所有带有”Chat-Version”头的邮件移入 DeltaChat 文件夹。并不是所有的提供商都支持此操作；通常情况下，这是由 Delta Chat 应用完成的。

启用“只从 DeltaChat 文件夹获取”是有意义的，仅当您同时完成了：

在这种情况下，Delta Chat 不需要监视收件箱，只监视 DeltaChat 文件夹就足够了。

如何将我的账户迁移到一个不同的电子邮件地址？

  1. Change your address in “Settings - Password and Account” and enter the password of your new account (and if necessary, server settings). You will get an information notice about the fact that you are moving to a new address. An additional notice will also show up in your “Device messages” chat.

  2. If possible, let your old e-mail provider forward all messages to your new address.

  3. Tell your contacts that you changed your address. Writing to guaranteed end-to-end encrypted chats and groups, will make them notice your move automatically and they will continue chatting with you using your new address.

Note that Delta Chat will not retrieve messages anymore from your old e-mail provider. If you didn’t configure your e-mail provider to forward messages (step 2.) only those contacts to whom you sent a message in a guaranteed end-to-end encrypted chat will send messages to your new address.

To learn more about this the details behind this, read our blogpost on it.

杂项

Delta Chat 可用于 我的 电子邮件提供商吗？

I want to manage my own e-mail server for Delta Chat. What do you recommend?

使用电子邮件的 Delta Chat 真的是 即时 通讯工具吗？

Can I set the E-Mail Subject with Delta Chat?

Delta Chat sets (and encrypts!) the classic e-mail subject automatically to the group name or to the sender name.

So if you want to set the subject yourself, for example for a formal e-mail to a business contact, you can create a group with only yourself and the recipient(s). Set the Chat Title to the Subject you want, and then send your e-mail as the first message. If the recipients don’t use Delta Chat, it will look like a normal, formal e-mail to them. You will get bonus professionalism points if you set a signature text.

Delta Chat 与 Protonmail / Tutanota / Criptext 兼容吗？

我对技术细节很感兴趣。能告诉我更多吗？

Delta Chat 的开发是如何被资助的?

Delta Chat 没有接受风险投资，也没有负债累累，更没有承受产生巨额利润或将用户及其朋友和家人卖给广告商（或更糟）的压力。我们宁愿使用（目前来自欧盟和美国的）公共资金，来帮助我们努力建立一个基于自由开源社区开发的、去中心化的、多样化的聊天消息（软件）生态系统。

具体来说，到目前为止，对 Delta Chat 开发的资助有这些来源：

上面提到的钱款资助主要是由在弗赖堡（德国）的 merlinux GmbH 组织的，分发给了来自世界各地的十多位贡献者。

Please see Delta Chat Contribution channels for both monetary and and other contribution possibilities.