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package: ODF: bump PBKDF2 iteration counts

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Given recent elections we need to build a higher wall to keep the
government out of our documents, and we will make the government
pay for it.

These iteration counts were considered appropriate a decade ago.

http://security.stackexchange.com/questions/3959/recommended-of-iterations-when-using-pkbdf2-sha256

We get similar numbers on SandyBridge-E desktop and Haswell i7-4600U laptop:
* with 10k iterations ~20 msec per derivation
* with 100k iterations ~195 msec per derivation
* with 150k iterations ~290 msec per derivation

We can't go too high though because in ODF every package stream gets
its own derived key with a different salt, so a document with embedded
images may need a lot of these.

Change-Id: I6894e71ed399f8c340eff97a9191c8d8419789a6
This commit is contained in:
Michael Stahl
2016-11-09 18:42:46 +01:00
parent 2a5bb08a2c
commit 25205d5b29
1 changed files with 2 additions and 2 deletions
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4
package/source/zippackage/ZipPackageStream.cxx
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@@ -655,7 +655,7 @@ bool ZipPackageStream::saveChild(
uno::Sequence < sal_Int8 > aSalt( 16 ), aVector( GetBlockSize() ); uno::Sequence < sal_Int8 > aSalt( 16 ), aVector( GetBlockSize() );
rtl_random_getBytes ( rRandomPool, aSalt.getArray(), 16 ); rtl_random_getBytes ( rRandomPool, aSalt.getArray(), 16 );
rtl_random_getBytes ( rRandomPool, aVector.getArray(), aVector.getLength() ); rtl_random_getBytes ( rRandomPool, aVector.getArray(), aVector.getLength() );
sal_Int32 nIterationCount = 1024; sal_Int32 const nPBKDF2IterationCount = 100000;
if ( !m_bHaveOwnKey ) if ( !m_bHaveOwnKey )
{ {
@@ -665,7 +665,7 @@ bool ZipPackageStream::saveChild(
setInitialisationVector ( aVector ); setInitialisationVector ( aVector );
setSalt ( aSalt ); setSalt ( aSalt );
setIterationCount ( nIterationCount ); setIterationCount(nPBKDF2IterationCount);
} }
// last property is digest, which is inserted later if we didn't have // last property is digest, which is inserted later if we didn't have