(See also https://github.com/openssl/openssl/pull/5154.)
The exponent here is one of d, dmp1, or dmq1 for RSA. This value and its
bit length are both secret. The only public upper bound is the bit width
of the corresponding modulus (RSA n, p, and q, respectively).
Although BN_num_bits is constant-time (sort of; see bn_correct_top notes
in preceding patch), this does not fix the root problem, which is that
the windows are based on the minimal bit width, not the upper bound. We
could use BN_num_bits(m), but BN_mod_exp_mont_consttime is public API
and may be called with larger exponents. Instead, use all top*BN_BITS2
bits in the BIGNUM. This is still sensitive to the long-standing
bn_correct_top leak, but we need to fix that regardless.
This may cause us to do a handful of extra multiplications for RSA keys
which are just above a whole number of words, but that is not a standard
RSA key size.
Change-Id: I5e2f12b70c303b27c597a7e513b7bf7288f7b0e3
Reviewed-on: https://boringssl-review.googlesource.com/25185
Commit-Queue: David Benjamin <davidben@google.com>
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These can be used to invert values in ECDSA. Unlike their BIGNUM
counterparts, the caller is responsible for taking values in and out of
Montgomery domain. This will save some work later on in the ECDSA
computation.
Change-Id: Ib7292900a0fdeedce6cb3e9a9123c94863659043
Reviewed-on: https://boringssl-review.googlesource.com/23071
Reviewed-by: Adam Langley <agl@google.com>
This was primarily for my own understanding, but this should hopefully
also be clearer and more amenable to using unsigned indices later.
Change-Id: I09cc3d55de0f7d9284d3b3168d8b0446274b2ab7
Reviewed-on: https://boringssl-review.googlesource.com/22889
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It always returns one, so just void it.
Change-Id: I8733cc3d6b20185e782cf0291e9c0dc57712bb63
Reviewed-on: https://boringssl-review.googlesource.com/22564
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This is an OpenSSL thing to support platforms where BN_ULONG is not
actually the size it claims to be. We define BN_ULONG to uint32_t and
uint64_t which are guaranteed by C to implement arithemetic modulo 2^32
and 2^64, respectively. Thus there is no need for any of this.
Change-Id: I098cd4cc050a136b9f2c091dfbc28dd83e01f531
Reviewed-on: https://boringssl-review.googlesource.com/21784
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crypto/{asn1,x509,x509v3,pem} were skipped as they are still OpenSSL
style.
Change-Id: I3cd9a60e1cb483a981aca325041f3fbce294247c
Reviewed-on: https://boringssl-review.googlesource.com/19504
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This isn't all of our pointer games by far, but for any code which
doesn't run on armv6, memcpy and pointer cast compile to the same code.
For code with does care about armv6 (do we care?), it'll need a bit more
work. armv6 makes memcpy into a function call.
Ironically, the one platform where C needs its alignment rules is the
one platform that makes it hard to honor C's alignment rules.
Change-Id: Ib9775aa4d9df9381995df8698bd11eb260aac58c
Reviewed-on: https://boringssl-review.googlesource.com/17707
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