# Coeffs polynomial mult in CKKS

**URL:** <https://openfhe.discourse.group/t/coeffs-polynomial-mult-in-ckks/2349>\
**Category:** Library Questions\
**Created:** [July 28, 2026, 12:59pm UTC](https://openfhe.discourse.group/t/coeffs-polynomial-mult-in-ckks/2349 "2026-07-28T12:59:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![narger](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/narger/32/420_2.png) [@narger](https://openfhe.discourse.group/u/narger)\
**Post date:** [July 28, 2026, 12:59pm UTC](https://openfhe.discourse.group/t/coeffs-polynomial-mult-in-ckks/2349/1 "2026-07-28T12:59:15Z")

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Hi all!

I have a question about polynomial mult in CKKS. in particular I’d have to multiply two plaintexts p, \hat{p} to obtain p \cdot \hat{p} \bmod \mathbb{Z}[X]/(X^N+1), _not_ in slot-wise.

As far as I am aware this can be done by “removing” the iDFT encoding, namely with a SlotsToCoeff procedure. I also know that the `EvalSlotsToCoeffs(p.m_U0PreFFT, ctxtEnc)` function computes exactly that, but inside the bootstrapping procedure, using bootstrapping precomputed material.

Is there a more friendly/adapt function to evaluate the SlotsToCoeff procedure \* outside \* of the bootstrapping to change the encoding of a ciphertext? thanks!

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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:** [August 3, 2026, 6:40pm UTC](https://openfhe.discourse.group/t/coeffs-polynomial-mult-in-ckks/2349/2 "2026-08-03T18:40:28Z")

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Please see [Implement CKKS- coefficient encoding multiplication](https://openfhe.discourse.group/t/implement-ckks-coefficient-encoding-multiplication/2164)