Generate Keypairs with strong prng provider (SHA1PRNG)

[Bernd]

Hello,

as a general precaution I wanted to document key generation best practice.
The SHA1PRNG with its small state and single 20 byte seed always is a bit
questionable for generating long term keys. 160 bit entropy (as long as the
SecureRandom instance is used only once) is not enough for larger RSA Keys
or AES192 and 256.

So I was looking for a solution which works on 8 and 9 and involves more
seed/state than the SHA1PRNG. On Windows the Windows-PRNG and on Linux the
NativePRNGs both look better in this regard. The
SecureRandom.getInstanceStrong() automatially uses them.

So while I think in the long run it might be better to wrap those
generators with DRBG some more I think a minimum is to use the strong
variant for key generation. I peeked into keytool to see whats best
practice and I noticed it does unfortunately NOT use the strong variant or
a DRBG configuration:

http://hg.openjdk.java.net/jdk9/jdk9/jdk/file/c95ebfceb394/src/java.base/share/classes/sun/security/tools/keytool/CertAndKeyGen.java#l150

Is it really acceptable for long term keys this way? (I guess no answer
means no :)

Would it be possible to bump the security level for keytool in 9?

Gruss
Bernd
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