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Fix BGV ring dimension underestimation with NOISE_FLOODING_MULTIPARTY + HYBRID on 128-bit builds#1158

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yspolyakov merged 4 commits into
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1157-fix-bgv-ring-dimension
Apr 7, 2026
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Fix BGV ring dimension underestimation with NOISE_FLOODING_MULTIPARTY + HYBRID on 128-bit builds#1158
yspolyakov merged 4 commits into
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1157-fix-bgv-ring-dimension

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@dsuponitskiy dsuponitskiy commented Mar 26, 2026 •
edited by yspolyakov
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BUG
We estimate P from estimated Q before the flooding primes are added. After that, the actual value of P is calculated from the actual Q in PrecomputeCRTTables(). In some 128-bit cases this made the real QP bigger than expected and failed generating a cryptocontext.

FIXES

  • Makes the P estimate include the flooding primes (this bug affected BGV and BFV)
  • Adds a check to compare estimated vs actual sizeP in PrecomputeCRTTables() and triggers an exception if there is a mismatch
  • Fixes another bug (affecting FIXEDMANUAL for BGV), which was detected by the new checking mechanism. An extra bit was added to an estimate of Q for FIXEDMANUAL, which caused a mismatch in the size limbs in P.

@dsuponitskiy dsuponitskiy added this to the Release 1.5.1 milestone Mar 26, 2026
@dsuponitskiy dsuponitskiy self-assigned this Mar 26, 2026
@dsuponitskiy dsuponitskiy added the bug Something isn't working label Mar 26, 2026
@dsuponitskiy dsuponitskiy requested a review from yspolyakov March 27, 2026 13:19
@yspolyakov yspolyakov linked an issue Mar 27, 2026 that may be closed by this pull request
Fix BGV ring dimension underestimation with NOISE_FLOODING_MULTIPARTY + HYBRID on 128-bit builds #1157
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yspolyakov
yspolyakov reviewed Mar 27, 2026
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Comment thread src/pke/lib/scheme/bgvrns/bgvrns-parametergeneration.cpp
@yspolyakov yspolyakov marked this pull request as draft March 27, 2026 19:37
yspolyakov
yspolyakov reviewed Apr 3, 2026
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Comment thread src/pke/lib/scheme/bgvrns/bgvrns-parametergeneration.cpp
@dsuponitskiy-duality
Addressed code review comments for BGV ring dimension underestimation…
d33c011 
… with NOISE_FLOODING_MULTIPARTY + HYBRID on 128-bit builds
@dsuponitskiy dsuponitskiy force-pushed the 1157-fix-bgv-ring-dimension branch from efd0d94 to d33c011 Compare April 6, 2026 10:49
yspolyakov
yspolyakov reviewed Apr 6, 2026
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Comment thread src/pke/include/schemerns/rns-cryptoparameters.h Outdated
yspolyakov
yspolyakov reviewed Apr 6, 2026
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Comment thread src/pke/include/schemerns/rns-cryptoparameters.h Outdated
yspolyakov
yspolyakov reviewed Apr 6, 2026
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Comment thread src/pke/lib/schemerns/rns-cryptoparameters.cpp Outdated
yspolyakov
yspolyakov reviewed Apr 6, 2026
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Comment thread src/pke/lib/schemerns/rns-cryptoparameters.cpp Outdated
@dsuponitskiy dsuponitskiy force-pushed the 1157-fix-bgv-ring-dimension branch from aa1640f to ee3c301 Compare April 6, 2026 19:43
@dsuponitskiy dsuponitskiy marked this pull request as ready for review April 7, 2026 14:34
@yspolyakov yspolyakov merged commit c5b4e36 into dev Apr 7, 2026
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@dsuponitskiy dsuponitskiy deleted the 1157-fix-bgv-ring-dimension branch April 7, 2026 14:58
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Fix BGV ring dimension underestimation with NOISE_FLOODING_MULTIPARTY + HYBRID on 128-bit builds

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