How can I integrate open source licenses, such as MIT, into my own open source project when my code is unlicensed? I want to use a portion of an existing project that is licensed under MIT. MIT seems to state that I must include their license in my work, but I don't want to use any license for my own work (i.e. unlicensed). Merely copying their license into my project makes it look like they wrote my entire project instead of just a portion of it. What is the correct way to integrate someone else's open source license into my project such that I am compliant with the requirements of their license, acknowledging their contribution, but remain able to license my own project a different way, including unlicensing my own work?
Basically, you cannot do it. You are required to include the MIT license in any derivative work. However, that holds only for the parts that you import from this other project. You can identify which parts of the final product are copied from the MIT-licensed program (and indicate "these parts are subject to the following MIT license"), and then you can do whatever you want with the remainder that you wrote. The downside of not licensing your material is that nobody can use it. To use it, people would need permission, which is what a license is. If you don't license it, you don't give permission, so people can't use it. You presumably want to subject your own contribution to different licensing conditions, so then you would state those conditions and clearly indicate what parts of the code you wrote.
Algorithms can be patented, e.g., https://en.wikipedia.org/wiki/RSA_(cryptosystem)#Patent (and see, e.g., https://en.wikipedia.org/wiki/Software_patent for further discussion). Copyright is only for specific code. So if your Company A has copyrighted the code you wrote, but not patented the algorithms implemented by that code, then you can subsequently go to Company B and legally reprogram those same algorithms.
Germany may be different, however in the United States this would be considered work-for-hire and the employer would be the rightful owner of the source code. Regardless of jurisdiction, and from a more practical point of view, you are better off not having a copy of the source code. Using it as reference or example in the future could easily turn into (unintentional) copyright infringement. If, in the future, you write code you would like to be able to freely keep and reuse in any project, make sure the owner/employer licenses it using something like the BSD, MIT, or ISC license.
It is certainly possible to transfer a copyright or other IP without an explicit charge, indeed it can be a pure gift, and normally would be when it is left by will, as is common enough. From a paid consultant it might be clearer to include a statement that the transfer is part of the consulting assignment, rather than putting a price of zero in a blank. But one could instead convey a permanent non-exclusive license, granting permission to use or modify the work in any way desired, ans saying that this is provided as part of the consulting process. Then there would be no question of what rights the consultant retained, or that the same or a very similar solution could be provided to different clients. Indeed such a license would not be so very different from a CC-BY license, or any of several open source licenses, although I would not use one of those by name. But the legal effect would be much the same, and the wording could be similar. Otherwise there could be a later claim that the right transferred precluded the consultant from using the same solution for other clients. Even if such a claim was not legally sound, and was not upheld, it could be a distraction and costly of time and energy at least.
If your own software includes software covered by the GPLv2 (for example by copying source code, or by linking dynamically) then your own software is also covered by the GPLv2, and you will have to provide the source code. This is called a "work based on the Program" on the GPLv2. In this case, however, it seems that your own software does not include software covered by the GPLv2, but you want to put it onto an SD card together with software covered by the GPLv2. That would most likely fall under "mere aggregation of another work", as long as your software and the other software do not interact very closely (such as dynamic linking). To quote the GPLv2: In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. So in that case the GPLv2 does not cover your program. You will still have to supply the source code for the GPLv2 software on the SD card. This is covered by section 3 of the GPLv2. Basically, you have two options: send along the complete source code for all the software (would be quite bothersome for a complete distro) or provide a written offer to provide the source code on demand to anyone who asks (you may charge for this, but only to cover your cost) GPLv2 contains a third option, but that only applies to non-commercial distribution. Practically speaking, it should be enough to include a README.txt or similar explaining that the SD card contains software covered by GPLv2, and that you will provide the source code on demand for a certain, reasonable fee (say $5 or $10 per CD). In practice, it is unlikely that anyone would ask for this, as the source code can usually be downloaded for free elsewhere, but if someone does ask, you just charge them $5 and send a CD. Of course, to reduce legal risks it may be prudent to contact a lawyer for your jurisdiction, as this is only general advice.
You probably can. There are a few questions here. First, is the message protected by copyright? In general, it probably is, but there are many exceptions that might allow you to use it without permission. Unfortunately, these exceptions vary from jurisdiction to jurisdiction. The exceptions tend to allow the use of small excerpts of a work for various sorts of purposes that don't undermine the copyright holder's ability to profit. That leads to the second question, which is why you are using that message. If you're including it in your source code so you can test whether a message generated at run time is in fact that message, that's one thing, and it's probably okay. On the other hand, if the owner of the copyright sells a database of all its message strings, and you're compiling a similar database that you also intend to sell, that's probably not okay. A third question concerns the Firefox license terms. It's entirely possible that they allow you explicitly to do what you're considering, in which case it doesn't matter what copyright law says about it. On the other hand, Firefox is open source software, and under some open source licenses, if you incorporate any of the source code in your own product, you are required to release your product's source code under the same license. If you're not already planning to do that, you should consider carefully whether including that error message would trigger that provision (if there is one) of Firefox's open source license.
Generally, such sanctions prevent certain sorts of transactions in goods and services with nationals or entities of the nation under sanction. The exact list of transactions prohibited or restricted varies. If Open source software were being provided as a service, so that the recipient paid directly for a license, or for customization or configuration work, or for some sort of consulting or assistance, such transactions could be banned or restricted by a sanctions regime, but might not be. (If the sanctions included that particular class of transactions.) However, if it is merely a matter of an open source product being published, for anyone to download, install, and use, I don't see how that would be barred or restricted by any sanctions of the sort recently in use.
Being or not being open source makes fairly little difference in trademark law. If a commercial firm (Yoyodyne, say) had used the name &quot;Portable Network Graphics&quot; and the abbreviation &quot;PNG&quot; in trade, and taken such further steps as would be needed to protect it in the relevant countries, that firm would have a protectable trademark. Note that in some countries, a trademark must be registered to have any protection at all (much of the EU follows this rule). In others, use in commerce can offer some protection even without registration (the US follows this rule). Had this happened (in an alternate reality) Yoyodyne could have sent a cease and desist letter when open source developers started using the mark. If the devs did not cease, Yoyodyne might have obtained an injunction, or damages for trademark infringement, or both. They could also have issued a takedown notie to the site hosting the project. But had Yoyodyne failed to defend the mark effectively and allowed it to become generic, Yoyodyne might have lost all rights to it. Also, had Yoyodyne ceased to use it in trade for a significant period, they might have lost rights. This is a place where the different laws in different countries might lead to different results. Note that &quot;Portable Network Graphics&quot; is rather descriptive, and not particularly distinctive. Descriptive marks, like &quot;Tasty Pizza&quot; generally get weaker protection, while more distinctive marks, such as &quot;LuAnn's Tastee Pizza&quot; are more strongly protected, in general. Again this depends on the country, and the specific facts. In general the first to use, or to register a mark, gets the rights. When one entity is the first to use, but a different one is first to register, things can get confusing, and results will be different in different countries. Note that a Cease and Desist letter is not a legal requirement. It is a threat of possible future legal action, and often an offer to avoid such action if the recipient does as the sender requests. The recipient can comply with the letter, wait for court action, or try to make some sort of compromise deal. Open source projects, as other answers suggest, often choose to comply.