All existing cipher suites use SHA-256 as the TLSv1.2 and above
handshake digest algorithm (even when using SHA-1 as the MAC digest
algorithm). Some GCM cipher suites use SHA-384 as the handshake
digest algorithm.
Allow the cipher suite to specify the handshake (and PRF) digest
algorithm to be used for TLSv1.2 and above.
This requires some restructuring to allow for the fact that the
ClientHello message must be included within the handshake digest, even
though the relevant digest algorithm is not yet known at the point
that the ClientHello is sent. Fortunately, the ClientHello may be
reproduced verbatim at the point of receiving the ServerHello, so we
rely on reconstructing (rather than storing) this message.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
TLS stream and block ciphers use a MAC with a length equal to the
output length of the digest algorithm in use. For AEAD ciphers there
is no MAC, with the equivalent functionality provided by the cipher
algorithm's authentication tag.
Allow for the existence of AEAD cipher suites by making the MAC length
a parameter of the cipher suite.
Assume that the MAC key length is equal to the MAC length, since this
is true for all currently supported cipher suites.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
TLS block ciphers always use CBC (as per RFC 5246 section 6.2.3.2)
with a record initialisation vector length that is equal to the cipher
block size, and no fixed initialisation vector.
The initialisation vector for AEAD ciphers such as GCM is less
straightforward, and requires both a fixed and per-record component.
Extend the definition of a cipher suite to include fixed and record
initialisation vector lengths, and generate the fixed portion (if any)
as part of key expansion.
Do not add explicit calls to cipher_setiv() in tls_assemble_block()
and tls_split_block(), since the constraints imposed by RFC 5246 are
specifically chosen to allow implementations to avoid doing so.
(Instead, add a sanity check that the record initialisation vector
length is equal to the cipher block size.)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There is nothing OID-specific about the ASN1_OID_CURSOR macro. Rename
to allow it to be used for constructing ASN.1 cursors with arbitrary
contents.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There are many ways in which the object for a cryptographic algorithm
may be included, even if not explicitly enabled in config/crypto.h.
For example: the MD5 algorithm is required by TLSv1.1 or earlier, by
iSCSI CHAP authentication, by HTTP digest authentication, and by NTLM
authentication.
In the current implementation, inclusion of an algorithm for any
reason will result in the algorithm's ASN.1 object identifier being
included in the "asn1_algorithms" table, which consequently allows the
algorithm to be used for any ASN1-identified purpose. For example: if
the MD5 algorithm is included in order to support HTTP digest
authentication, then iPXE would accept a (validly signed) TLS
certificate using an MD5 digest.
Split the ASN.1 object identifiers into separate files that are
required only if explicitly enabled in config/crypto.h. This allows
an algorithm to be omitted from the "asn1_algorithms" table even if
the algorithm implementation is dragged in for some other purpose.
The end result is that only the algorithms that are explicitly enabled
in config/crypto.h can be used for ASN1-identified purposes such as
signature verification.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add support for SHA-224, SHA-384, and SHA-512 as digest algorithms in
X.509 certificates, and allow the choice of public-key, cipher, and
digest algorithms to be configured at build time via config/crypto.h.
Originally-implemented-by: Tufan Karadere <tufank@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
