PK: declare restartable sign/verify functions
For RSA, we could either have the function return an error code like
NOT_IMPLEMENTED or just run while disregarding ecp_max_ops. IMO the second
option makes more sense, as otherwise the caller would need to check whether
the key is EC or RSA before deciding to call either sign() or
sign_restartable(), and having to do this kind of check feels contrary to the
goal of the PK layer.
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index f9f9b9b..05c51d3 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -285,6 +285,33 @@
const unsigned char *sig, size_t sig_len );
/**
+ * \brief Restartable version of \c mbedtls_pk_verify()
+ *
+ * \note Performs the same job as \c mbedtls_pk_verify(), but can
+ * return early and restart according to the limit set with
+ * \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
+ * operations. For RSA, same as \c mbedtls_pk_verify().
+ *
+ * \param ctx PK context to use
+ * \param md_alg Hash algorithm used (see notes)
+ * \param hash Hash of the message to sign
+ * \param hash_len Hash length or 0 (see notes)
+ * \param sig Signature to verify
+ * \param sig_len Signature length
+ * \param rs_ctx Restart context: for ECC, must be NULL (no restart) or a
+ * pointer to a \c mbedtls_ecdsa_restart_ctx. Ignored for RSA.
+ *
+ * \return See \c mbedtls_pk_verify(), or
+ * MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ * operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
+ mbedtls_md_type_t md_alg,
+ const unsigned char *hash, size_t hash_len,
+ const unsigned char *sig, size_t sig_len,
+ void *rs_ctx );
+
+/**
* \brief Verify signature, with options.
* (Includes verification of the padding depending on type.)
*
@@ -348,6 +375,36 @@
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
/**
+ * \brief Restartable version of \c mbedtls_pk_sign()
+ *
+ * \note Performs the same job as \c mbedtls_pk_sign(), but can
+ * return early and restart according to the limit set with
+ * \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
+ * operations. For RSA, same as \c mbedtls_pk_sign().
+ *
+ * \param ctx PK context to use - must hold a private key
+ * \param md_alg Hash algorithm used (see notes)
+ * \param hash Hash of the message to sign
+ * \param hash_len Hash length or 0 (see notes)
+ * \param sig Place to write the signature
+ * \param sig_len Number of bytes written
+ * \param f_rng RNG function
+ * \param p_rng RNG parameter
+ * \param rs_ctx Restart context: for ECC, must be NULL (no restart) or a
+ * pointer to a \c mbedtls_ecdsa_restart_ctx. Ignored for RSA.
+ *
+ * \return See \c mbedtls_pk_sign(), or
+ * MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ * operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
+ mbedtls_md_type_t md_alg,
+ const unsigned char *hash, size_t hash_len,
+ unsigned char *sig, size_t *sig_len,
+ int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+ void *rs_ctx );
+
+/**
* \brief Decrypt message (including padding if relevant).
*
* \param ctx PK context to use - must hold a private key