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add minimum matrix size to reduce disclosure risk #500

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add minimum matrix size to reduce disclosure risk #500

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7cb57fc
add disclosure check for matrix assign function
timcadman Jul 23, 2026
3ce7ef8
revert: add back in list check
timcadman Jul 23, 2026
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11 changes: 11 additions & 0 deletions R/matrixDetDS1.R
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,11 @@

matrixDetDS1 <- function(M1.name=NULL,logarithm){

dsBase::checkPermissivePrivacyControlLevel(c('permissive', 'avocado', 'banana'))

thr <- dsBase::listDisclosureSettingsDS()
nfilter.subset <- as.numeric(thr$nfilter.subset)

M1 <- .loadServersideObject(M1.name)
.checkClass(obj = M1, obj_name = M1.name, permitted_classes = c("matrix", "data.frame"))

Expand All @@ -33,6 +38,12 @@ if(ncol(M1)!=nrow(M1))
stop(error.message, call. = FALSE)
}

#Check matrix large enough to reduce disclosure risk
if(nrow(M1)<nfilter.subset)
{
error.message<-"FAILED: matrix is too small (nrows < nfilter.subset), please respecify"
stop(error.message, call. = FALSE)
}

output<-determinant(M1,logarithm=logarithm)

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22 changes: 18 additions & 4 deletions tests/testthat/test-smk-matrixDetDS1.R
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Expand Up @@ -11,11 +11,10 @@ set.standard.disclosure.settings()
# Tests
#

test_that("simple matrixDetDS1", {
M1 <- matrix(c(1, 2, 3, 4), 2, 2)

test_that("simple matrixDetDS1 passes with matrix of sufficient dimensions", {
M1 <- matrix(c(1, 2, 3, 4, 5, 6, 7, 8, 10), 3, 3)
res <- matrixDetDS1("M1", logarithm=FALSE)

expect_true(is.list(res))
expect_equal(res$matrix.determinant, determinant(M1, logarithm=FALSE))
})
Expand All @@ -28,3 +27,18 @@ test_that("matrixDetDS1 errors when input is wrong type", {
bad_input <- c("a", "b", "c")
expect_error(matrixDetDS1("bad_input", logarithm=FALSE), regexp = "must be of type")
})

test_that("matrixDetDS1 errors when matrix is too small (disclosure guard)", {
M1x1 <- matrix(7, 1, 1)
M2x2 <- matrix(c(1, 2, 3, 4), 2, 2)

expect_error(matrixDetDS1("M1x1", logarithm=FALSE), regexp = "too small")
expect_error(matrixDetDS1("M2x2", logarithm=FALSE), regexp = "too small")
})

test_that("matrixDetDS1 is blocked in non-permissive mode", {
options(datashield.privacyControlLevel = "non-permissive")
on.exit(options(datashield.privacyControlLevel = NULL), add = TRUE)
M1 <- matrix(c(1, 2, 3, 4, 5, 6, 7, 8, 10), 3, 3)
expect_error(matrixDetDS1("M1", logarithm=FALSE), regexp = "non-permissive")
})
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