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Imagine the following scenario. A process is running in background and permanently encrypting some data. An adversary has full control of the process, e.g. it can dump the process memory any time and read the symmetric key. It is essential that the adversary cannot decrypt the data, therefore only public-key encryption without any symmetric cipher component is feasible.

What would be the best method for data encryption in this scenario using ECC?

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    $\begingroup$ No matter the encryption used, wouldn't the process memory contain the plaintext data before it is encrypted, anyway? $\endgroup$ – fkraiem Dec 10 '19 at 12:10
  • $\begingroup$ For this application it is allowed. The question is purely cryptography-related: what would be the ECC analogy to RSA? $\endgroup$ – Andy Dec 10 '19 at 12:47
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    $\begingroup$ If your question is that, then just ask that. Why make up a nonsensical example? $\endgroup$ – fkraiem Dec 10 '19 at 12:52
  • $\begingroup$ As remarked bt fkraiem, we can't hope to protect the plaintext from a probing right when it arrives. Thus the best we can unconditionally achieve is that probing an encryption compromises neither the previous nor the next. I see no reason to ban internal use of symmetric crypto, if its symmetric key is ECC-generated. Anything wrong with ECIES? $\endgroup$ – fgrieu Dec 10 '19 at 13:21
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    $\begingroup$ That said, it does seem to answer the question. Hmm. Andy, is that enough of an answer for you (EC El Gamal)? $\endgroup$ – Maarten Bodewes Dec 10 '19 at 16:00
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ECC cant really be used to encrypt and decrypt data - it doesn't have the required properties. An asymmetric cipher such as RSA would have to be used, as this can encrypt and decrypt data.

ECC can be used for bilateral key exchanges, and to sign/verify data. RSA can sign/verify data, do KEMs, and encrypt/decrypt data.

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    $\begingroup$ Actually, ECC could be used directly on data; for example, use a simple mapping of data to EC points, and then use EC El Gamal (as mentioned in the comments). Whether it solves any specific problem, and whether it makes sense, is another question; however, you could do it... $\endgroup$ – poncho Dec 14 '19 at 23:36

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