in Algebraic Methods in Cryptography, Contemporary Mathematics vol. 418, AMS, pp. 133-140, 2006.
We give an attack on a public key encryption scheme suggested by Shpilrain and Zapata. Experimental evidence shows that this attack is practical and works for the proposed parameters. We give a way to repair the encryption scheme so that our attack does not work anymore. However, we also expose weak points of the scheme that do not seem to be repairable in an obvious manner.
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