frost/secp256k1-zkp
3
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Make randomization of a non-signing context a noop

Browse Source 
Before this commit secp256k1_context_randomize called illegal_callback
when called on a context not initialized for signing. This is not
documented. Moreover, it is not desirable because non-signing contexts
may use randomization in the future.

This commit makes secp256k1_context_randomize a noop in this case. This
is safe because the context cannot be used for signing anyway.

This fixes #573 and it fixes rust-bitcoin/rust-secp256k1#82.
This commit is contained in:
Tim Ruffing
2019-01-27 13:17:37 +01:00
parent b8c1bc517e
commit edd941c94b
3 changed files with 15 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
include/secp256k1.h
View File

@@ -653,7 +653,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Updates the context randomization to protect against side-channel leakage.
* Returns: 1: randomization successfully updated
* Returns: 1: randomization successfully updated or nothing to randomize
* 0: error
* Args: ctx: pointer to a context object (cannot be NULL)
* In: seed32: pointer to a 32-byte random seed (NULL resets to initial state)
@@ -668,6 +668,11 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
* that it does not affect function results, but shields against attacks which
* rely on any input-dependent behaviour.
*
* This function has currently an effect only on contexts initialized for signing
* because randomization is currently used only for signing. However, this is not
* guaranteed and may change in the future. It is safe to call this function on
* contexts not initialized for signing; then it will have no effect and return 1.
*
* You should call this after secp256k1_context_create or
* secp256k1_context_clone (and secp256k1_context_preallocated_create or
* secp256k1_context_clone, resp.), and you may call this repeatedly afterwards.