# Failed by Sign Evaluation challenge

**URL:** <https://openfhe.discourse.group/t/failed-by-sign-evaluation-challenge/1944>\
**Category:** FHE Challenges\
**Created:** [March 19, 2025, 3:16am UTC](https://openfhe.discourse.group/t/failed-by-sign-evaluation-challenge/1944 "2025-03-19T03:16:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![capibala](https://avatars.discourse-cdn.com/v4/letter/c/b5ac83/32.png) [@capibala](https://openfhe.discourse.group/u/capibala)\
**Post date:** [March 19, 2025, 3:16am UTC](https://openfhe.discourse.group/t/failed-by-sign-evaluation-challenge/1944/1 "2025-03-19T03:16:47Z")

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run [GitHub - Fherma-challenges/signum: Signum challenge repository](https://github.com/Fherma-challenges/signum)

./app --key\_pub ../key\_pub.txt --key\_mult ../key\_mult.txt --cc ../cc.json --input ../input.txt --output ../output.txt  
terminate called after throwing an instance of ‘cereal::Exception’  
what(): Trying to load a registered polymorphic type with an unregistered polymorphic cast.  
Could not find a path to a base class (lbcrypto::EncodingParamsImpl) for type: lbcrypto::CryptoParametersCKKSRNS  
Make sure you either serialize the base class at some point via cereal::base\_class or cereal::virtual\_base\_class.  
Alternatively, manually register the association with CEREAL\_REGISTER\_POLYMORPHIC\_RELATION.  
Aborted (core dumped)

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**Author:** ![gurgen](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@gurgen](https://openfhe.discourse.group/u/gurgen)\
**Post date:** [March 26, 2025, 3:15pm UTC](https://openfhe.discourse.group/t/failed-by-sign-evaluation-challenge/1944/2 "2025-03-26T15:15:29Z")

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Which version of the library are you using?