authenc methods vs FIPS in light of unencrypted associated data

From	Marcus Meissner <meissner@suse.de>
Newsgroups	linux.kernel
Subject	authenc methods vs FIPS in light of unencrypted associated data
Date	2016-06-02 18:10 +0200
Message-ID	<rFDm2-82K-35@gated-at.bofh.it> (permalink)
Organization	SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)

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Hi,

In February I already tagged some authenc ciphers for FIPS compatibility.

I currently revisit this to get testmgr running all the tests in strict FIPS mode.

The authenc() class is troublesome.

There is a HASH + ENC part of this method, but you can also add associated data,
which is not encrypted. (using the ctx->null cipher in crypto/authenc.c)

But in FIPS mode the crypto_authenc_init_tfm does:

	null = crypto_get_default_null_skcipher();

which results in error, as the crypto_alloc_blkcipher("ecb(cipher_null)", 0, 0);
results in failure due to "ecb(cipher_null)" not FIPS compliant.

How to handle this?

I think GCM also does not encrypt, just hashes, the associated data, it just does
copy the content itself and does not use a virtual cipher.

Ciao, Marcus

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authenc methods vs FIPS in light of unencrypted associated data Marcus Meissner <meissner@suse.de> - 2016-06-02 18:10 +0200
  Re: authenc methods vs FIPS in light of unencrypted associated data Stephan Mueller <smueller@chronox.de> - 2016-06-03 08:50 +0200
    Re: authenc methods vs FIPS in light of unencrypted associated data Herbert Xu <herbert@gondor.apana.org.au> - 2016-06-03 12:20 +0200

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