adec5a16383f1704d80d7c767b2a65d9221cee08 Add missing null check for ctx and input keys in the public API (Elichai Turkel)
f4edfc758142d6e100ca5d086126bf532b8a7020 Improve consistency for NULL arguments in the public interface (Elichai Turkel)
Pull request description:
I went over the public API and added missing explanations on when a pointer can be null and when it cannot,
and added some missing checks for null ctx and null pubkey pointers.
Open questions IMHO:
1. Can `secp256k1_context_create` return NULL? right now it could return null if you replaced the callbacks at compile time to ones that do return(unlike the default ones which never return).
2. Related to the first, should we document that the callbacks should never return? (in the tests we use returning callbacks but we can violate our own API) right now we say the following:
> After this callback returns, anything may happen, including crashing.
Is this enough to document answer `no` for the first question and just saying that if the callback returned then you violated the API so `secp256k1_context_create` can return NULL even though it is promised not to?
Right now we AFAICT we never check if it returns null
Another nit I'm not sure about is wording `(does nothing if NULL)`/`(ignored if NULL)`/`(can be NULL)`
More missing docs:
1. Documenting the `data` argument to the default nonce functions
ACKs for top commit:
ariard:
ACK adec5a16
jonasnick:
ACK adec5a16383f1704d80d7c767b2a65d9221cee08
Tree-SHA512: 6fe785776b7e451e9e8cae944987f927b1eb2e2d404dfcb1b0ceb0a30bda4ce16469708920269417e5ada09739723a430e270dea1868fe7d12ccd5699dde5976
unsigned char foo[4] = "abcd" is not valid C++ because the string
literal "abcd" does not fit into foo due to the terminating NUL
character. This is valid in C, it will just omit the NUL character.
Fixes#962.
Varlen message support for the default sign function comes from recommending
tagged_sha256. sign_custom on the other hand gets the ability to directly sign
message of any length. This also implies signing and verification support for
the empty message (NULL) with msglen 0.
Tests for variable lengths follow in a later commit.
This makes the default sign function easier to use while allowing more granular
control through sign_custom.
Tests for sign_custom follow in a later commit.
33cb3c2b1fc3f3fe46c6d0eab118248ea86c1f06 Add secret key extraction from keypair to constant time tests (Elichai Turkel)
36d9dc1e8e6e3b15d805f04c973a8784a78880f6 Add seckey extraction from keypair to the extrakeys tests (Elichai Turkel)
fc96aa73f5c7f62452847a31821890ff1f72a5a4 Add a function to extract the secretkey from a keypair (Elichai Turkel)
Pull request description:
With schnorrsig if you need to tweak the secret key (for BIP32) you must use the keypair API to get compatible secret/public keys which you do by calling `secp256k1_keypair_xonly_tweak_add()`, but after that there's no currently a way to extract the secret key back for storage.
so I added a `secp256k1_keypair_seckey` function to extract the key
ACKs for top commit:
jonasnick:
ACK 33cb3c2b1fc3f3fe46c6d0eab118248ea86c1f06
real-or-random:
ACK 33cb3c2b1fc3f3fe46c6d0eab118248ea86c1f06 code inspection, tests pass
Tree-SHA512: 11212db38c8b87a87e2dc35c4d6993716867b45215b94b20522b1b3164ca63d4c6bf5192a6bff0e9267b333779cc8164844c56669a94e9be72df9ef025ffcfd4
As identified in #829 and #833. Fixes#829.
Since we touch this anyway, this commit additionally makes the
identifiers in the benchmark files a little bit more consistent.
This enables testing overflow is correctly encoded in the recid, and
likely triggers more edge cases.
Also introduce a Sage script to generate the parameters.
7b50483ad789081ba158799e5b94330f62932607 Adds a declassify operation to aid constant-time analysis. (Gregory Maxwell)
34a67c773b0871e5797c7ab506d004e80911f120 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 7b50483ad789081ba158799e5b94330f62932607
real-or-random:
ACK 7b50483ad789081ba158799e5b94330f62932607 I read the code carefully and tested it
jonasnick:
reACK 7b50483ad789081ba158799e5b94330f62932607
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.
