Add iovec routines for both padded CBC, and CTS EVP based encryption.
These routines go to great lengths to minimise the number of times
we call EVP_Cipher. With some EVP implementations (such as OpenSSL's
AES-NI) there is a significant entrance and exit overhead from this
routine, due to the use of SIMD vectors for the ivec.
Add a encrypt_iov function pointer to all of our encryption types
which can be used to implement an iovec based encryption routine.
Modify krb5_encrypt_iov so that it calls the iovec based routine
if it is available.
Creating and destroying an EVP_CTX_MD structure with every hash
operation is very expensive. Speed things up by caching one within
the krb5_crypto structure. krb5_crypto can already only be safely
used by one thread at a time - adding a message digest context here
shouldn't introduce any further threading risks.
Users of the stashed context must be careful to ensure that they
call no other hash functions whilst they are in the middle of using
the context.
Modify the signature of the checksum operation in the
krb5_checksum_type structure so that it processes iovecs rather than
solid blocks of data.
Update all of the implementations of these functions for all of the
checksum types that we support so that they process iovecs, either
by iterating through the iovec in each function, or by calling
_krb5_evp_digest_iov or _krb5_evp_hmac_iov()
Update callers of these functions so that they turn their single blocks
of data into a single iovec of the correct type before calling checksum
RFC 3961 says the simplified profile PRF should truncate the hash
output to "multiple of m", which MIT krb5 interprets as the largest
possible multiple of m. RFC 6113 appendix A also uses that
interpretation for the KRB-FX-CF2 test vector. So the DES3 PRF should
truncate the 20-byte SHA-1 result to 16 bytes, not 8. Also make
krb5_crypto_prf_length work with DES3 by giving the DES3 enctype a
non-zero PRF length.
Signed-off-by: Nicolas Williams <nico@cryptonector.com>
lib/krb5/crypto.c was a large, monolithic block of code which made
it very difficult to selectively enable and disable particular
alogrithms.
Reorganise crypto.c into individual files for each encryption and
salt time, and place the structures which tie everything together
into their own file (crypto-algs.c)
Add a non-installed library (librfc3961) and test program
(test_rfc3961) which builds a minimal rfc3961 crypto library, and
checks that it is usable.
