Update README.md

README.md

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+# Warning
+
+The SIDH and SIKE protocols were proven insecure after a series of attacks starting with [14]. 
+Therefore, these protocols MUST NOT be used in production.
+
+The SIDH library is only presented here for historical reasons, and because some functionality may be reusable in other cryptographic applications.
+
 # SIDH v3.5.1 (C Edition)
 
 The **SIDH** library is an efficient supersingular isogeny-based cryptography library written in C language.
@@ -263,6 +270,9 @@ The preprint version is available [`here`](https://eprint.iacr.org/2020/431).
 [13]  Patrick Longa, "Efficient algorithms for large prime characteristic fields and their application to bilinear pairings and supersingular isogeny-based protocols", 2022.
 The preprint version is available [`here`](https://eprint.iacr.org/2022/367).
 
+[14]  Wouter Castryck and Thomas Decru, "An efficient key recovery attack on SIDH", 2022. 
+The preprint version is available [`here`](https://eprint.iacr.org/2022/975).
+
 # Contributing
 
 This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [[email protected]](mailto:[email protected]) with any additional questions or comments.