# Library Questions **URL:** https://openfhe.discourse.group/c/user-questions/17.md?page=2 [Latest](https://openfhe.discourse.group/latest.md) · [Categories](https://openfhe.discourse.group/categories.md) · [Tags](https://openfhe.discourse.group/tags.md) **Page:** 3 --- ## [EvalSum exposes more then just sum](https://openfhe.discourse.group/t/evalsum-exposes-more-then-just-sum/2208)
**Author:** [@lukisko](https://openfhe.discourse.group/u/lukisko)\ **Replies:** 1\ **Last updated:** [November 10, 2025, 4:51pm UTC](https://openfhe.discourse.group/t/evalsum-exposes-more-then-just-sum/2208 "2025-11-10T16:51:27Z")
Action: Running example file threshold-fhe.py, (openfhe-python/examples/pke/threshold-fhe.py at main · openfheorg/openfhe-python · GitHub) Actual result: Output of EvalSum on plaintext3 (2, 2, 3, 4, 5, 6, 7, 8, 9, 10,… --- ## [Did the EvalSum() API use hoisted rotations?](https://openfhe.discourse.group/t/did-the-evalsum-api-use-hoisted-rotations/2207)
**Author:** [@capibala](https://openfhe.discourse.group/u/capibala)\ **Replies:** 1\ **Last updated:** [November 10, 2025, 4:18pm UTC](https://openfhe.discourse.group/t/did-the-evalsum-api-use-hoisted-rotations/2207 "2025-11-10T16:18:34Z")
I saw in the previous question that EvalSumRows/Cols did not use hoisted rotations. Does EvalSum use this technique? --- ## [Security Guarantees and Best Practices for FIXED\_NOISE\_MULTIPARTY vs. NOISE\_FLOODING\_MULTIPARTY](https://openfhe.discourse.group/t/security-guarantees-and-best-practices-for-fixed-noise-multiparty-vs-noise-flooding-multiparty/1784)
**Author:** [@keiyou](https://openfhe.discourse.group/u/keiyou)\ **Replies:** 6\ **Last updated:** [November 10, 2025, 4:13pm UTC](https://openfhe.discourse.group/t/security-guarantees-and-best-practices-for-fixed-noise-multiparty-vs-noise-flooding-multiparty/1784 "2025-11-10T16:13:45Z")
Hi everyone. I have been working with multiparty BFV and BGV in OpenFHE and noticed that the default setting is FIXED\_NOISE\_MULTIPARTY. My understanding is that this approach uses deterministic (fixed) noise rather than… --- ## [What is the purpose of FindAutomorphismIndex?](https://openfhe.discourse.group/t/what-is-the-purpose-of-findautomorphismindex/1086)
**Author:** [@j2kun](https://openfhe.discourse.group/u/j2kun)\ **Replies:** 8\ **Last updated:** [November 10, 2025, 4:12pm UTC](https://openfhe.discourse.group/t/what-is-the-purpose-of-findautomorphismindex/1086 "2025-11-10T16:12:36Z")
I am studying the pke part of OpenFHE and I’m curious to understand the reason for having the FindAutomorphismIndex method. --- ## ["The decryption failed because the approximation error is too high. Check the parameters" with bootstrapping](https://openfhe.discourse.group/t/the-decryption-failed-because-the-approximation-error-is-too-high-check-the-parameters-with-bootstrapping/2206)
**Author:** [@cappuccino](https://openfhe.discourse.group/u/cappuccino)\ **Replies:** 2\ **Last updated:** [November 7, 2025, 8:04am UTC](https://openfhe.discourse.group/t/the-decryption-failed-because-the-approximation-error-is-too-high-check-the-parameters-with-bootstrapping/2206 "2025-11-07T08:04:22Z")
I’m using the CKKS cipher and encountered the following error: The decryption failed because the approximation error is too high. Check the parameters. I checked out Error “The decryption failed because the approximati… --- ## [About precision, scale value and basic operation of boot strapping](https://openfhe.discourse.group/t/about-precision-scale-value-and-basic-operation-of-boot-strapping/2204)
**Author:** [@cappuccino](https://openfhe.discourse.group/u/cappuccino)\ **Replies:** 3\ **Last updated:** [November 6, 2025, 5:03pm UTC](https://openfhe.discourse.group/t/about-precision-scale-value-and-basic-operation-of-boot-strapping/2204 "2025-11-06T17:03:26Z")
While using bootstrap with the following program, three questions came to mind. Isn’t the accuracy of the bootstrapped ciphertext low? I can observe a 50-bit → 10-bit error. The scale value of the bootstrapped ciph… --- ## [Can I use arbitrarily large ciphertext moduli (q\_i) in BGV/BFV?](https://openfhe.discourse.group/t/can-i-use-arbitrarily-large-ciphertext-moduli-q-i-in-bgv-bfv/2203)
**Author:** [@oksuman](https://openfhe.discourse.group/u/oksuman)\ **Replies:** 3\ **Last updated:** [November 6, 2025, 5:42am UTC](https://openfhe.discourse.group/t/can-i-use-arbitrarily-large-ciphertext-moduli-q-i-in-bgv-bfv/2203 "2025-11-06T05:42:46Z")
Hello, I’m wondering whether it is possible to use arbitrarily large ciphertext moduli (q\_i) in the BGV or BFV schemes. In particular, I would like to set a large first modulus (q\_0), up to about 800 bits. However, I f… --- ## [Segmentation Fault when Implementing EvalStC/EvalCtS Methods in CKKS](https://openfhe.discourse.group/t/segmentation-fault-when-implementing-evalstc-evalcts-methods-in-ckks/2084)
**Author:** [@haohaohao](https://openfhe.discourse.group/u/haohaohao)\ **Replies:** 4\ **Last updated:** [November 6, 2025, 3:32am UTC](https://openfhe.discourse.group/t/segmentation-fault-when-implementing-evalstc-evalcts-methods-in-ckks/2084 "2025-11-06T03:32:38Z")
Problem Overview I’m trying to implement direct access methods for Slots-to-Coefficients (EvalStC) and Coefficients-to-Slots (EvalCtS) transformations in CKKS bootstrapping. While EvalBootstrap works perfectly, calling E… --- ## [Easy way to evaluate N/2 polynomials over N/2 slots](https://openfhe.discourse.group/t/easy-way-to-evaluate-n-2-polynomials-over-n-2-slots/2194)
**Author:** [@narger](https://openfhe.discourse.group/u/narger)\ **Replies:** 3\ **Last updated:** [November 5, 2025, 11:13pm UTC](https://openfhe.discourse.group/t/easy-way-to-evaluate-n-2-polynomials-over-n-2-slots/2194 "2025-11-05T23:13:45Z")
Hi everyone :slight\_smile: I have a quick question: in CKKS we can evaluate a polynomial by a set of coefficients on the whole slots of a ciphertext. Does OpenFHE allow for the SIMD evaluation of n/2 polynomials (of sam… --- ## [About bootstrapping parameters](https://openfhe.discourse.group/t/about-bootstrapping-parameters/2202)
**Author:** [@cappuccino](https://openfhe.discourse.group/u/cappuccino)\ **Replies:** 2\ **Last updated:** [October 31, 2025, 8:07pm UTC](https://openfhe.discourse.group/t/about-bootstrapping-parameters/2202 "2025-10-31T20:07:41Z")
Hello everyone I’m working on bootstrapping on CKKS. I have three questions: How does levelBudget work? What are the advantages of having a large levelBudget and a small levelBudget? As above, what is bsgsDim? Wh… --- ## [How to set bootstrapping parameters with ringdimensions of 2^16 and 128-bit security](https://openfhe.discourse.group/t/how-to-set-bootstrapping-parameters-with-ringdimensions-of-2-16-and-128-bit-security/2199)
**Author:** [@cappuccino](https://openfhe.discourse.group/u/cappuccino)\ **Replies:** 2\ **Last updated:** [October 31, 2025, 5:22pm UTC](https://openfhe.discourse.group/t/how-to-set-bootstrapping-parameters-with-ringdimensions-of-2-16-and-128-bit-security/2199 "2025-10-31T17:22:48Z")
Hello everyone! Thank you for always providing such a great library! I’m currently conducting research using CKKS and am a beginner. I’ve never used bootstrapping before, in particular. So, I have a question: when ac… --- ## [Support for NOISE\_FLOODING\_MULTIPARTY in threshold CKKS?](https://openfhe.discourse.group/t/support-for-noise-flooding-multiparty-in-threshold-ckks/2197)
**Author:** [@oksuman](https://openfhe.discourse.group/u/oksuman)\ **Replies:** 2\ **Last updated:** [October 31, 2025, 5:19am UTC](https://openfhe.discourse.group/t/support-for-noise-flooding-multiparty-in-threshold-ckks/2197 "2025-10-31T05:19:45Z")
Hello, I noticed that the NOISE\_FLOODING\_MULTIPARTY option seems to be unsupported for threshold CKKS in the OpenFHE implementation. Could you please explain the reason for this design choice or limitation? Also, woul… --- ## [How to support 55 (q\_0) + 40 (q\_i), i\>0 in OpenFHE](https://openfhe.discourse.group/t/how-to-support-55-q-0-40-q-i-i-0-in-openfhe/2195)
**Author:** [@JianmingTong](https://openfhe.discourse.group/u/JianmingTong)\ **Replies:** 1\ **Last updated:** [October 20, 2025, 4:39pm UTC](https://openfhe.discourse.group/t/how-to-support-55-q-0-40-q-i-i-0-in-openfhe/2195 "2025-10-20T16:39:57Z")
Dear developers Might I seek guidance on how to implement the following security parameters inside OpenFHE and make it able to pass the 128-bit security checking? I’m using this example to test the bootstrapping open… --- ## [Batch size and rotation](https://openfhe.discourse.group/t/batch-size-and-rotation/2192)
**Author:** [@Rak](https://openfhe.discourse.group/u/Rak)\ **Replies:** 3\ **Last updated:** [October 16, 2025, 9:12pm UTC](https://openfhe.discourse.group/t/batch-size-and-rotation/2192 "2025-10-16T21:12:06Z")
Using some ideeas of the simple-real-numbers example ( openfhe-development/src/pke/examples/simple-real-numbers.cpp at main · openfheorg/openfhe-development · GitHub ), I would like to do some computations on the followi… --- ## [Do CKKS evalSumRows/Cols implicitly use hoisting for rotations?](https://openfhe.discourse.group/t/do-ckks-evalsumrows-cols-implicitly-use-hoisting-for-rotations/2191)
**Author:** [@luca97](https://openfhe.discourse.group/u/luca97)\ **Replies:** 1\ **Last updated:** [October 13, 2025, 8:07pm UTC](https://openfhe.discourse.group/t/do-ckks-evalsumrows-cols-implicitly-use-hoisting-for-rotations/2191 "2025-10-13T20:07:42Z")
Hi, I was trying to understand whether the EvalSumRows and EvalSumCols functions implemented in OpenFHE for CKKS implicitly leverage hoisting. By looking at the code, I found thatEvalFastRotate, which does use hoisting … --- ## [Cause of "Requested bit length 60 exceeds maximum allowed length 57"](https://openfhe.discourse.group/t/cause-of-requested-bit-length-60-exceeds-maximum-allowed-length-57/2186)
**Author:** [@maxgruebmeyer](https://openfhe.discourse.group/u/maxgruebmeyer)\ **Replies:** 2\ **Last updated:** [October 8, 2025, 12:13pm UTC](https://openfhe.discourse.group/t/cause-of-requested-bit-length-60-exceeds-maximum-allowed-length-57/2186 "2025-10-08T12:13:52Z")
Hi all, I’m supporting the development of the openfhe-julia wrapper. However, when executing our tests locally, I get the following error message: parameters = MyOpenFHE.CCParams{MyOpenFHE.CryptoContextCKKSRNS}() = MyO… --- ## [Cannot using HEStd\_128\_classic crashes my terminal](https://openfhe.discourse.group/t/cannot-using-hestd-128-classic-crashes-my-terminal/2187)
**Author:** [@Omar](https://openfhe.discourse.group/u/Omar)\ **Replies:** 1\ **Last updated:** [October 3, 2025, 6:59am UTC](https://openfhe.discourse.group/t/cannot-using-hestd-128-classic-crashes-my-terminal/2187 "2025-10-03T06:59:40Z")
Hello, I’m trying to run the following simple program in CKKS, it’s similar to the code in advanced-ckks-bootstrapping.cpp. I’m using WSL on Windows and the program compiles. But when I run it, it prints “CKKS scheme is… --- ## [Bug in \`RPATH\`/\`RUNPATH\` specification in \`CMakeLists.txt\`](https://openfhe.discourse.group/t/bug-in-rpath-runpath-specification-in-cmakelists-txt/1071)
**Author:** [@sloede](https://openfhe.discourse.group/u/sloede)\ **Replies:** 3\ **Last updated:** [September 30, 2025, 6:00pm UTC](https://openfhe.discourse.group/t/bug-in-rpath-runpath-specification-in-cmakelists-txt/1071 "2025-09-30T18:00:18Z")
It seems to me like there is a bug in CMakeLists.txt with respect to the correct RPATH setting. Note: While this issue was detected and verified on Linux, it is likely it pertains also to macOS. In the CMAKE\_INSTALL\_… --- ## [Library feature request: Setting moduli chain directly](https://openfhe.discourse.group/t/library-feature-request-setting-moduli-chain-directly/2183)
**Author:** [@raghavst](https://openfhe.discourse.group/u/raghavst)\ **Replies:** 3\ **Last updated:** [September 30, 2025, 4:36am UTC](https://openfhe.discourse.group/t/library-feature-request-setting-moduli-chain-directly/2183 "2025-09-30T04:36:07Z")
Hello. Somewhat continuing the discussion in this thread, it would be helpful for researchers/benchmarking if the moduli chain for Q and P could be specified directly. Thus I am posting this feature request. --- ## [Questions about MultiPrecision FBT](https://openfhe.discourse.group/t/questions-about-multiprecision-fbt/2177)
**Author:** [@Haow\_P](https://openfhe.discourse.group/u/Haow_P)\ **Replies:** 4\ **Last updated:** [September 25, 2025, 1:58pm UTC](https://openfhe.discourse.group/t/questions-about-multiprecision-fbt/2177 "2025-09-25T13:58:59Z")
Hi, I am currently working with the latest version of OpenFHE and trying to understand the Functional Bootstrapping (FBT) procedure. In the MultiPrecisionSign example in functional-bootstrapping-ckks.cpp, I have the fol… --- ## [Setting the special primes p](https://openfhe.discourse.group/t/setting-the-special-primes-p/2180)
**Author:** [@raghavst](https://openfhe.discourse.group/u/raghavst)\ **Replies:** 3\ **Last updated:** [September 24, 2025, 8:14am UTC](https://openfhe.discourse.group/t/setting-the-special-primes-p/2180 "2025-09-24T08:14:59Z")
From this post Question about the composition of the modular chain, I understand the following about the parameters for the modulus Q and its RNS decomposition: 1) multDepth + 1 is equal to the moduli chain length q\_0, .… --- ## [OpenFHE Rescaling with Issues after scheme switching with CKKS and TFHE/FHEW](https://openfhe.discourse.group/t/openfhe-rescaling-with-issues-after-scheme-switching-with-ckks-and-tfhe-fhew/2179)
**Author:** [@seanmoris](https://openfhe.discourse.group/u/seanmoris)\ **Replies:** 2\ **Last updated:** [September 24, 2025, 5:47am UTC](https://openfhe.discourse.group/t/openfhe-rescaling-with-issues-after-scheme-switching-with-ckks-and-tfhe-fhew/2179 "2025-09-24T05:47:59Z")
Hi all, I’m stuck with weird rescaling error when using OpenFHE CKKS. After multiplying an encrypted index gotten from EvalMaxSchemeSwitching by some plaintext and accumulating results, decryption fails consistently. B… --- ## [Compatibility Issue with Linear Transform Pre-computation in OpenFHE v1.4 (Imaginary Mode)](https://openfhe.discourse.group/t/compatibility-issue-with-linear-transform-pre-computation-in-openfhe-v1-4-imaginary-mode/2178)
**Author:** [@haohaohao](https://openfhe.discourse.group/u/haohaohao)\ **Replies:** 2\ **Last updated:** [September 23, 2025, 8:16am UTC](https://openfhe.discourse.group/t/compatibility-issue-with-linear-transform-pre-computation-in-openfhe-v1-4-imaginary-mode/2178 "2025-09-23T08:16:20Z")
Hi everyone, I recently upgraded from OpenFHE v1.3 to v1.4 and encountered an issue with a previously working code implementation. The code involves testing S2C and C2S operations, both running in imaginary mode. Afte… --- ## [Why does decryption of a fresh ciphertext, or a single EvalMul using a plaintext and a fresh ciphertext, result in NaN?](https://openfhe.discourse.group/t/why-does-decryption-of-a-fresh-ciphertext-or-a-single-evalmul-using-a-plaintext-and-a-fresh-ciphertext-result-in-nan/2163)
**Author:** [@YKSK](https://openfhe.discourse.group/u/YKSK)\ **Replies:** 2\ **Last updated:** [September 22, 2025, 8:50pm UTC](https://openfhe.discourse.group/t/why-does-decryption-of-a-fresh-ciphertext-or-a-single-evalmul-using-a-plaintext-and-a-fresh-ciphertext-result-in-nan/2163 "2025-09-22T20:50:27Z")
I have a question regarding the Python wrapper for OpenFHE (version 0.8.4). I encountered an issue. The problem is that the result of decrypting a fresh ciphertext, or of decrypting a ciphertext that has been through a… --- ## [Eval chebyshev poly without range](https://openfhe.discourse.group/t/eval-chebyshev-poly-without-range/2176)
**Author:** [@narger](https://openfhe.discourse.group/u/narger)\ **Replies:** 7\ **Last updated:** [September 19, 2025, 5:08pm UTC](https://openfhe.discourse.group/t/eval-chebyshev-poly-without-range/2176 "2025-09-19T17:08:00Z")
Hello, I have some polynomials under Chebyshev basis that I found via some techniques in a python code. Now I would like to use these polynomials under CKKS, and I was thinking of using the EvalChebyshevSeries (openfhe-… --- ## [Openfhe-python Dockerfile missing file setup.py](https://openfhe.discourse.group/t/openfhe-python-dockerfile-missing-file-setup-py/2174)
**Author:** [@SWC](https://openfhe.discourse.group/u/SWC)\ **Replies:** 1\ **Last updated:** [September 18, 2025, 4:07pm UTC](https://openfhe.discourse.group/t/openfhe-python-dockerfile-missing-file-setup-py/2174 "2025-09-18T16:07:12Z")
Hi all, I’m trying to download the Python wrapper for OpenFHE through Docker. However, I keep having the error: \[8/9\] RUN python3 setup.py sdist bdist\_wheel && pip install dist/openfhe-\*.whl: 0.288 python3: can’t ope… --- ## [Complex Number Multiplication](https://openfhe.discourse.group/t/complex-number-multiplication/2173)
**Author:** [@div](https://openfhe.discourse.group/u/div)\ **Replies:** 1\ **Last updated:** [September 15, 2025, 8:16pm UTC](https://openfhe.discourse.group/t/complex-number-multiplication/2173 "2025-09-15T20:16:14Z")
I know that openfhe uses complex number for packing. So let’s say I am doing this opeation batch\_size = 4 inp = \[1+1j, 0+0j, 1+0j\] scale = \[2.4+3.2j, 6.2+6j, 8.2+11j\] pt = cc.MakeCKKSPackedPlaintext(inp) ct = cc.Encryp… --- ## [Question about general FBT](https://openfhe.discourse.group/t/question-about-general-fbt/2157)
**Author:** [@Haow\_P](https://openfhe.discourse.group/u/Haow_P)\ **Replies:** 9\ **Last updated:** [September 16, 2025, 5:45pm UTC](https://openfhe.discourse.group/t/question-about-general-fbt/2157 "2025-09-16T17:45:45Z")
Hi, all In the functional-bootstrapping-ckks, the ArbitraryLUT example begins with a BFV ciphertext, and use \`SchemeletRLWEMP::convert\` to convert ciphertext type into CKKS, then perform FBT on the CKKS ciphertext. I’m… --- ## [How to create a DiscreteUniformGeneratorImpl\ with a system installed openFHE](https://openfhe.discourse.group/t/how-to-create-a-discreteuniformgeneratorimpl-dcrtpoly-with-a-system-installed-openfhe/2172)
**Author:** [@MarcR](https://openfhe.discourse.group/u/MarcR)\ **Replies:** 2\ **Last updated:** [September 16, 2025, 9:56am UTC](https://openfhe.discourse.group/t/how-to-create-a-discreteuniformgeneratorimpl-dcrtpoly-with-a-system-installed-openfhe/2172 "2025-09-16T09:56:34Z")
Hi everyone. Here is the issue I am facing. I need to generate some numbers following a uniform distribution inside my project. I use a system installation of openFHE. I can instantiate the following dug : lbcrypto… --- ## [How to link OpenFHE libraries in Windows](https://openfhe.discourse.group/t/how-to-link-openfhe-libraries-in-windows/2169)
**Author:** [@Mona](https://openfhe.discourse.group/u/Mona)\ **Replies:** 2\ **Last updated:** [September 15, 2025, 8:20pm UTC](https://openfhe.discourse.group/t/how-to-link-openfhe-libraries-in-windows/2169 "2025-09-15T20:20:14Z")
Hi, I installed the OpenFHE using MSYS2 MINGW 64-bit shell in my Windows OS. I followed the instructions on this page I was able to run the simple-integers executable in cd \\~/openfhe-development/build/bin/examples/… [Previous page](https://openfhe.discourse.group/c/user-questions/17.md?page=1) [Next page](https://openfhe.discourse.group/c/user-questions/17.md?page=3)