# What is the CKKS bootstrapping algorithm in openfhe?

**URL:** <https://openfhe.discourse.group/t/what-is-the-ckks-bootstrapping-algorithm-in-openfhe/1826>\
**Category:** FHE Questions\
**Created:** [January 9, 2025, 7:05am UTC](https://openfhe.discourse.group/t/what-is-the-ckks-bootstrapping-algorithm-in-openfhe/1826 "2025-01-09T07:05:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hionwi](https://avatars.discourse-cdn.com/v4/letter/h/46a35a/32.png) [@hionwi](https://openfhe.discourse.group/u/hionwi)\
**Post date:** [January 9, 2025, 7:05am UTC](https://openfhe.discourse.group/t/what-is-the-ckks-bootstrapping-algorithm-in-openfhe/1826/1 "2025-01-09T07:05:39Z")

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I am studying bootstrapping in CKKS recently. Could anyone give me some papers about CKKS bootstrapping?

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**Author:** ![Caesar](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/caesar/32/63_2.png) [@Caesar](https://openfhe.discourse.group/u/Caesar)\
**Post date:** [January 10, 2025, 12:10am UTC](https://openfhe.discourse.group/t/what-is-the-ckks-bootstrapping-algorithm-in-openfhe/1826/2 "2025-01-10T00:10:24Z")

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These are good resources on CKKS bootstrapping, OpenFHE uses ideas from these papers.

1. The original CKKS bootstrapping was proposed here. [Bootstrapping for Approximate Homomorphic Encryption](https://eprint.iacr.org/2018/153.pdf)
2. An improved variant focusing on more optimized implementations of linear transforms and sine function evaluation was proposed here [Improved Bootstrapping for Approximate Homomorphic Encryption](https://eprint.iacr.org/2018/1043.pdf)
3. Alternative secret key settings beyond sparse configurations, along with further optimizations such as double-hoisting were proposed here [Efficient Bootstrapping for Approximate Homomorphic Encryption with Non-Sparse Keys](https://eprint.iacr.org/2020/1203.pdf)