7b50483ad7 Adds a declassify operation to aid constant-time analysis. (Gregory Maxwell)
34a67c773b Eliminate harmless non-constant time operations on secret data. (Gregory Maxwell)
Pull request description:
There were several places where the code was non-constant time
for invalid secret inputs. These are harmless under sane use
but get in the way of automatic const-time validation.
(Nonce overflow in signing is not addressed, nor is s==0 in signing)
ACKs for top commit:
sipa:
utACK 7b50483ad7
real-or-random:
ACK 7b50483ad7 I read the code carefully and tested it
jonasnick:
reACK 7b50483ad7
Tree-SHA512: 0776c3a86e723d2f97b9b9cb31d0d0e59dfcf308093b3f46fbc859f73f9957f3fa977d03b57727232040368d058701ef107838f9b1ec98f925ec78ddad495c4e
There were several places where the code was non-constant time
for invalid secret inputs. These are harmless under sane use
but get in the way of automatic const-time validation.
(Nonce overflow in signing is not addressed, nor is s==0 in
signing)
Most of the codebase correctly used short-cutting to avoid calling
_is_zero on possibly incompletely initialized elements, but a few
places were missed.
Identifiers starting with an underscore and followed immediately by a capital letter are reserved by the C++ standard.
The only header guards not fixed are those in the headers auto-generated from java.
Make sure we clear the nonce data even if the nonce function fails (it may have written partial data), and call memset only once in the case we iterate to produce a valid signature.
Make sure we clear the nonce data even if the nonce function fails (it may have written partial data), and call memset only once in the case we iterate to produce a valid signature.
There are now 2 encoding formats supported: 64-byte "compact" and DER.
The latter is strict: the data has to be exact DER, though the values
inside don't need to be valid.
Libtool will do the right thing and use whatever is available
based on --enable-shared/--enable-static.
This also means that some of the things we build actually
test the dynamic library.
This makes it more clear that a null check is intended. Avoiding the
use of a pointer as a test condition alse increases the type-safety
of the comparisons.
(This is also MISRA C 2012 rules 14.4 and 11.9)
Pieter Wuille
Jonas Nick
Elichai Turkel
Tim Ruffing
Gregory Maxwell
Kirill Fomichev
Andrew Poelstra
Pieter Wuille
Dan Raviv
bgorlick
Wladimir J. van der Laan
Luke Dashjr
Cory Fields