# Sign evaluation and addition

**URL:** <https://openfhe.discourse.group/t/sign-evaluation-and-addition/636>\
**Category:** Library Questions\
**Created:** [June 15, 2023, 12:04pm UTC](https://openfhe.discourse.group/t/sign-evaluation-and-addition/636 "2023-06-15T12:04:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![miiip](https://avatars.discourse-cdn.com/v4/letter/m/a183cd/32.png) [@miiip](https://openfhe.discourse.group/u/miiip)\
**Post date:** [June 15, 2023, 12:04pm UTC](https://openfhe.discourse.group/t/sign-evaluation-and-addition/636/1 "2023-06-15T12:04:54Z")

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Hi all,  
I know that we can make secure comparisons using BinFHE. Is it possible to use BinFHE to add (or multiply) two encrypted integers?

Thank you!

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**Author:** ![ypolyakov](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/ypolyakov/32/47_2.png) [@ypolyakov](https://openfhe.discourse.group/u/ypolyakov)\
**Post date:** [June 16, 2023, 11:51pm UTC](https://openfhe.discourse.group/t/sign-evaluation-and-addition/636/2 "2023-06-16T23:51:34Z")

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For LWE ciphertexts, BinFHE supports addition and multiplication by a constant (standard methods for an additive HE scheme; see [Program Listing for File lwe-pke.h — OpenFHE documentation](https://openfhe-development.readthedocs.io/en/latest/api/program_listing_file_binfhe_include_lwe-pke.h.html?highlight=LWE) for the API). Multiplication by an encrypted integer requires an SHE scheme, like Ring-GSW, which is not supported in BinFHE. Multiplication can be done at a bit level or using arbitrary function evaluation, but this would be too expensive. A more efficient way is to use scheme switching, where multiplications can be done using another scheme, like CKKS or BFV. Scheme switching for CKKS ↔ FHEW will be added in v1.1 (later this summer).