Add ecdsa_from_keypair()
Also fix bug/limitation in mpi_copy: would segfault if src just initialised
and not set to a value yet. (This case occurs when copying a context which
contains only the public part of the key, eg.)
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 6746233..bdb3567 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -283,6 +283,20 @@
ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
}
+/*
+ * Set context from an ecp_keypair
+ */
+int ecdsa_from_keypair( ecdsa_context *ctx, const ecp_keypair *key )
+{
+ int ret = ecp_group_copy( &ctx->grp, &key->grp ) ||
+ mpi_copy( &ctx->d, &key->d ) ||
+ ecp_copy( &ctx->Q, &key->Q );
+
+ if( ret != 0 )
+ ecdsa_free( ctx );
+
+ return( ret );
+}
/*
* Initialize context