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The only way for an adversary to access messages sent by Signal is if it has direct physical access to your or the recipient’s phone.Įven then, Signal includes the option to encrypt all stored messages, which make it impossible to access them unless the phone owner can somehow be coerced into revealing their passcode. This removes the need to trust any third party to keep your data safe, and no third party can access the messages in transit. Signal uses end-to-end encryptionĪll secure Signal messages are encrypted on your phone before being sent, and can only be decrypted by the intended recipient(s). For further discussion on this subject please see Why Open Source is so Important. For this reason, you should only trust open source apps such as Signal to keep your communications secure and private. With closed source code there is no way to know what the code is really doing, and so closed source code cannot be trusted to keep your communications secure. Signal was fully independently audited in 2016 and was found to be cryptographically secure. This means that it can be independently audited for errors and to ensure that it isn’t doing something it shouldn’t. Open source software is software whose source code has been made publicly available by its copyright holder. Although mainly a mobile app, a desktop version also exists. In addition to text and SMS messaging, Signal also supports secure voice (VoIP) and video calls between users. The beauty of this system is that Signal is almost transparent in use, which should make it easier to convince friends, family, and colleagues to use the app!
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I will discuss this issue more a little later. Because it is designed to replace your regular SMS client, Signal requires that you register with a valid phone number.
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This setup ensures that Signal is seamless to use when sending text messages to both other Signal users and to non-users. When sending an insecure text message you are warned that it is insecure and are encouraged to invite your contact to use Signal. Messages to and from non-Signal contacts are sent using regular SMS text messaging and are not secure. Messages to and from other Signal users are sent over the internet and protected by very strong end-to-end encryption. Signal is primarily a secure and open source messaging app that replaces your Android phone or iPhone’s regular SMS app.
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