Squashed 'src/secp256k1/' changes from 642c885b61..2f2ccc4695

2f2ccc4695 Merge bitcoin-core/secp256k1#1600: cmake: Introduce `SECP256K1_APPEND_LDFLAGS` variable
421ed1b46f cmake: Introduce `SECP256K1_APPEND_LDFLAGS` variable
1988855079 Merge bitcoin-core/secp256k1#1586: fix: remove duplicate 'the' from header file comment
b307614401 Merge bitcoin-core/secp256k1#1583: ci: Bump GCC_SNAPSHOT_MAJOR to 15
fa67b6752d refactor: Use array initialization for unterminated strings
9b0f37bff1 fix: remove duplicate 'the' from header file comment
e34b476730 ci: Bump GCC_SNAPSHOT_MAJOR to 15
3fdf146bad Merge bitcoin-core/secp256k1#1578: ci: Silent Homebrew's noisy reinstall warnings
f8c1b0e0e6 Merge bitcoin-core/secp256k1#1577: release cleanup: bump version after 0.5.1
7057d3c9af ci: Silent Homebrew's noisy reinstall warnings
c3e40d75db release cleanup: bump version after 0.5.1

git-subtree-dir: src/secp256k1
git-subtree-split: 2f2ccc469540fde6495959cec061e95aab033148

.github/workflows/ci.yml

@@ -437,12 +437,44 @@ jobs:
       - name: Build
         working-directory: build
         run: |
-          cmake --build . -j $env:NUMBER_OF_PROCESSORS --config Release
+          brew install --quiet automake libtool gcc
+          ln -s $(brew --prefix gcc)/bin/gcc-?? /usr/local/bin/gcc
+
+      - name: Install and cache Valgrind
+        uses: ./.github/actions/install-homebrew-valgrind
 
       - name: Run test suite
         working-directory: build
         run: |
-          ctest -j $env:NUMBER_OF_PROCESSORS -C Release
+          brew install --quiet automake libtool gcc
+          ln -s $(brew --prefix gcc)/bin/gcc-?? /usr/local/bin/gcc
+
+      - name: CI script
+        env: ${{ matrix.env_vars }}
+        run: ./ci/ci.sh
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  win64-native:
+    name: ${{ matrix.configuration.job_name }}
+    # See: https://github.com/actions/runner-images#available-images.
+    runs-on: windows-2022
 
       - name: Run functional tests
         working-directory: build

CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
 ## [0.5.1] - 2024-08-01
 
 #### Added
@@ -141,6 +143,7 @@ This version was in fact never released.
 The number was given by the build system since the introduction of autotools in Jan 2014 (ea0fe5a5bf0c04f9cc955b2966b614f5f378c6f6).
 Therefore, this version number does not uniquely identify a set of source files.
 
+[unreleased]: https://github.com/bitcoin-core/secp256k1/compare/v0.5.1...HEAD
 [0.5.1]: https://github.com/bitcoin-core/secp256k1/compare/v0.5.0...v0.5.1
 [0.5.0]: https://github.com/bitcoin-core/secp256k1/compare/v0.4.1...v0.5.0
 [0.4.1]: https://github.com/bitcoin-core/secp256k1/compare/v0.4.0...v0.4.1

CMakeLists.txt

@@ -1,43 +1,13 @@
-# Copyright (c) 2023-present The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or https://opensource.org/license/mit/.
-
-# Ubuntu 22.04 LTS Jammy Jellyfish, https://wiki.ubuntu.com/Releases, EOSS in June 2027:
-#  - CMake 3.22.1, https://packages.ubuntu.com/jammy/cmake
-#
-# Centos Stream 9, https://www.centos.org/cl-vs-cs/#end-of-life, EOL in May 2027:
-#  - CMake 3.26.5, https://mirror.stream.centos.org/9-stream/AppStream/x86_64/os/Packages/
-cmake_minimum_required(VERSION 3.22)
-
-if (${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_BINARY_DIR})
-  message(FATAL_ERROR "In-source builds are not allowed.")
-endif()
-
-#=============================
-# Project / Package metadata
-#=============================
-set(PACKAGE_NAME "Bitgesell Core")
-set(CLIENT_VERSION_MAJOR 27)
-set(CLIENT_VERSION_MINOR 99)
-set(CLIENT_VERSION_BUILD 0)
-set(CLIENT_VERSION_RC 0)
-set(CLIENT_VERSION_IS_RELEASE "false")
-set(COPYRIGHT_YEAR "2024")
-
-# During the enabling of the CXX and CXXOBJ languages, we modify
-# CMake's compiler/linker invocation strings by appending the content
-# of the user-defined `APPEND_*` variables, which allows overriding
-# any flag. We also ensure that the APPEND_* flags are considered
-# during CMake's tests, which use the `try_compile()` command.
-#
-# CMake's docs state that the `CMAKE_TRY_COMPILE_PLATFORM_VARIABLES`
-# variable "is meant to be set by CMake's platform information modules
-# for the current toolchain, or by a toolchain file." We do our best
-# to set it before the `project()` command.
-set(CMAKE_TRY_COMPILE_PLATFORM_VARIABLES
-  CMAKE_CXX_COMPILE_OBJECT
-  CMAKE_OBJCXX_COMPILE_OBJECT
-  CMAKE_CXX_LINK_EXECUTABLE
+cmake_minimum_required(VERSION 3.16)
+
+project(libsecp256k1
+  # The package (a.k.a. release) version is based on semantic versioning 2.0.0 of
+  # the API. All changes in experimental modules are treated as
+  # backwards-compatible and therefore at most increase the minor version.
+  VERSION 0.5.2
+  DESCRIPTION "Optimized C library for ECDSA signatures and secret/public key operations on curve secp256k1."
+  HOMEPAGE_URL "https://github.com/bitcoin-core/secp256k1"
+  LANGUAGES C
 )
 
 project(BitcoinCore
@@ -111,8 +81,19 @@ if(WITH_BDB)
 endif()
 cmake_dependent_option(BUILD_WALLET_TOOL "Build BGL-wallet tool." ${BUILD_TESTS} "ENABLE_WALLET" OFF)
 
-option(BUILD_UTIL_CHAINSTATE "Build experimental BGL-chainstate executable." OFF)
-option(BUILD_KERNEL_LIB "Build experimental BGLkernel library." ${BUILD_UTIL_CHAINSTATE})
+# The library version is based on libtool versioning of the ABI. The set of
+# rules for updating the version can be found here:
+# https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
+# All changes in experimental modules are treated as if they don't affect the
+# interface and therefore only increase the revision.
+set(${PROJECT_NAME}_LIB_VERSION_CURRENT 4)
+set(${PROJECT_NAME}_LIB_VERSION_REVISION 2)
+set(${PROJECT_NAME}_LIB_VERSION_AGE 2)
+
+set(CMAKE_C_STANDARD 90)
+set(CMAKE_C_EXTENSIONS OFF)
+
+list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 
 option(ENABLE_WALLET "Enable wallet." ON)
 option(WITH_SQLITE "Enable SQLite wallet support." ${ENABLE_WALLET})
@@ -571,8 +552,17 @@ if(DEFINED ENV{LDFLAGS})
   deduplicate_flags(CMAKE_EXE_LINKER_FLAGS)
 endif()
 
-if(BUILD_TESTS)
-  enable_testing()
+set(SECP256K1_APPEND_LDFLAGS "" CACHE STRING "Linker flags that are appended to the command line after all other flags added by the build system. This variable is intended for debugging and special builds.")
+if(SECP256K1_APPEND_LDFLAGS)
+  # Appending to this low-level rule variable is the only way to
+  # guarantee that the flags appear at the end of the command line.
+  string(APPEND CMAKE_C_CREATE_SHARED_LIBRARY " ${SECP256K1_APPEND_LDFLAGS}")
+  string(APPEND CMAKE_C_LINK_EXECUTABLE " ${SECP256K1_APPEND_LDFLAGS}")
+endif()
+
+add_subdirectory(src)
+if(SECP256K1_BUILD_EXAMPLES)
+  add_subdirectory(examples)
 endif()
 # TODO: The `CMAKE_SKIP_BUILD_RPATH` variable setting can be deleted
 #       in the future after reordering Guix script commands to
@@ -642,16 +632,52 @@ else()
   set(cross_status "FALSE")
 endif()
 message("Cross compiling ....................... ${cross_status}")
-message("C++ compiler .......................... ${CMAKE_CXX_COMPILER_ID} ${CMAKE_CXX_COMPILER_VERSION}, ${CMAKE_CXX_COMPILER}")
-include(FlagsSummary)
-flags_summary()
-message("Attempt to harden executables ......... ${ENABLE_HARDENING}")
-message("Use ccache for compiling .............. ${WITH_CCACHE}")
-message("\n")
-if(configure_warnings)
-    message("  ******\n")
-    foreach(warning IN LISTS configure_warnings)
-      message(WARNING "${warning}")
-    endforeach()
-    message("  ******\n")
+message("Valgrind .............................. ${SECP256K1_VALGRIND}")
+get_directory_property(definitions COMPILE_DEFINITIONS)
+string(REPLACE ";" " " definitions "${definitions}")
+message("Preprocessor defined macros ........... ${definitions}")
+message("C compiler ............................ ${CMAKE_C_COMPILER_ID} ${CMAKE_C_COMPILER_VERSION}, ${CMAKE_C_COMPILER}")
+message("CFLAGS ................................ ${CMAKE_C_FLAGS}")
+get_directory_property(compile_options COMPILE_OPTIONS)
+string(REPLACE ";" " " compile_options "${compile_options}")
+message("Compile options ....................... " ${compile_options})
+if(NOT is_multi_config)
+  message("Build type:")
+  message(" - CMAKE_BUILD_TYPE ................... ${CMAKE_BUILD_TYPE}")
+  string(TOUPPER "${CMAKE_BUILD_TYPE}" build_type)
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_${build_type}}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_${build_type}}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_${build_type}}")
+else()
+  message("Supported configurations .............. ${CMAKE_CONFIGURATION_TYPES}")
+  message("RelWithDebInfo configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_RELWITHDEBINFO}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO}")
+  message("Debug configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_DEBUG}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_DEBUG}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_DEBUG}")
+endif()
+if(SECP256K1_APPEND_CFLAGS)
+  message("SECP256K1_APPEND_CFLAGS ............... ${SECP256K1_APPEND_CFLAGS}")
+endif()
+if(SECP256K1_APPEND_LDFLAGS)
+  message("SECP256K1_APPEND_LDFLAGS .............. ${SECP256K1_APPEND_LDFLAGS}")
+endif()
+message("")
+if(print_msan_notice)
+  message(
+    "Note:\n"
+    "  MemorySanitizer detected, tried to add -fno-sanitize-memory-param-retval to compile options\n"
+    "  to avoid false positives in ctime_tests. Pass -DSECP256K1_BUILD_CTIME_TESTS=OFF to avoid this.\n"
+  )
+endif()
+if(SECP256K1_EXPERIMENTAL)
+  message(
+    "  ******\n"
+    "  WARNING: experimental build\n"
+    "  Experimental features do not have stable APIs or properties, and may not be safe for production use.\n"
+    "  ******\n"
+  )
 endif()

ci/linux-debian.Dockerfile

@@ -24,8 +24,56 @@ RUN dpkg --add-architecture i386 && \
 RUN apt-get update && apt-get install --no-install-recommends -y \
         git ca-certificates \
         make automake libtool pkg-config dpkg-dev valgrind qemu-user \
-        gcc g++ clang libclang-rt-dev libc6-dbg \
-        gcc-i686-linux-gnu g++-i686-linux-gnu libc6-dev-i386-cross libc6-dbg:i386 \
-        g++-s390x-linux-gnu libstdc++6:s390x gcc-s390x-linux-gnu libc6-dev-s390x-cross libc6-dbg:s390x \
-        wine wine64 g++-mingw-w64-x86-64
+        gcc clang llvm libclang-rt-dev libc6-dbg \
+        g++ \
+        gcc-i686-linux-gnu libc6-dev-i386-cross libc6-dbg:i386 libubsan1:i386 libasan8:i386 \
+        gcc-s390x-linux-gnu libc6-dev-s390x-cross libc6-dbg:s390x \
+        gcc-arm-linux-gnueabihf libc6-dev-armhf-cross libc6-dbg:armhf \
+        gcc-powerpc64le-linux-gnu libc6-dev-ppc64el-cross libc6-dbg:ppc64el \
+        gcc-mingw-w64-x86-64-win32 wine64 wine \
+        gcc-mingw-w64-i686-win32 wine32 \
+        python3 && \
+        if ! ( dpkg --print-architecture | grep --quiet "arm64" ) ; then \
+         apt-get install --no-install-recommends -y \
+         gcc-aarch64-linux-gnu libc6-dev-arm64-cross libc6-dbg:arm64 ;\
+        fi && \
+        apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Build and install gcc snapshot
+ARG GCC_SNAPSHOT_MAJOR=15
+RUN apt-get update && apt-get install --no-install-recommends -y wget libgmp-dev libmpfr-dev libmpc-dev flex && \
+    mkdir gcc && cd gcc && \
+    wget --progress=dot:giga --https-only --recursive --accept '*.tar.xz' --level 1 --no-directories "https://gcc.gnu.org/pub/gcc/snapshots/LATEST-${GCC_SNAPSHOT_MAJOR}" && \
+    wget "https://gcc.gnu.org/pub/gcc/snapshots/LATEST-${GCC_SNAPSHOT_MAJOR}/sha512.sum" && \
+    sha512sum --check --ignore-missing sha512.sum && \
+    # We should have downloaded exactly one tar.xz file
+    ls && \
+    [ $(ls *.tar.xz | wc -l) -eq "1" ] && \
+    tar xf *.tar.xz && \
+    mkdir gcc-build && cd gcc-build && \
+    ../*/configure --prefix=/opt/gcc-snapshot --enable-languages=c --disable-bootstrap --disable-multilib --without-isl && \
+    make -j $(nproc) && \
+    make install && \
+    cd ../.. && rm -rf gcc && \
+    ln -s /opt/gcc-snapshot/bin/gcc /usr/bin/gcc-snapshot && \
+    apt-get autoremove -y wget libgmp-dev libmpfr-dev libmpc-dev flex && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Install clang snapshot, see https://apt.llvm.org/
+RUN \
+    # Setup GPG keys of LLVM repository
+    apt-get update && apt-get install --no-install-recommends -y wget && \
+    wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc && \
+    # Add repository for this Debian release
+    . /etc/os-release && echo "deb http://apt.llvm.org/${VERSION_CODENAME} llvm-toolchain-${VERSION_CODENAME} main" >> /etc/apt/sources.list && \
+    apt-get update && \
+    # Determine the version number of the LLVM development branch
+    LLVM_VERSION=$(apt-cache search --names-only '^clang-[0-9]+$' | sort -V | tail -1 | cut -f1 -d" " | cut -f2 -d"-" ) && \
+    # Install
+    apt-get install --no-install-recommends -y "clang-${LLVM_VERSION}" && \
+    # Create symlink
+    ln -s "/usr/bin/clang-${LLVM_VERSION}" /usr/bin/clang-snapshot && \
+    # Clean up
+    apt-get autoremove -y wget && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
 

src/secp256k1/configure.ac

@@ -4,18 +4,18 @@ AC_PREREQ([2.60])
 # the API. All changes in experimental modules are treated as
 # backwards-compatible and therefore at most increase the minor version.
 define(_PKG_VERSION_MAJOR, 0)
-define(_PKG_VERSION_MINOR, 3)
-define(_PKG_VERSION_PATCH, 3)
+define(_PKG_VERSION_MINOR, 5)
+define(_PKG_VERSION_PATCH, 2)
 define(_PKG_VERSION_IS_RELEASE, false)
 
 # The library version is based on libtool versioning of the ABI. The set of
 # rules for updating the version can be found here:
 # https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
 # All changes in experimental modules are treated as if they don't affect the
 # interface and therefore only increase the revision.
-define(_LIB_VERSION_CURRENT, 2)
-define(_LIB_VERSION_REVISION, 3)
-define(_LIB_VERSION_AGE, 0)
+define(_LIB_VERSION_CURRENT, 4)
+define(_LIB_VERSION_REVISION, 2)
+define(_LIB_VERSION_AGE, 2)
 
 AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_PATCH)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-dev]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1])
 

src/secp256k1/examples/schnorr.c

@@ -18,9 +18,9 @@
 #include "random.h"
 
 int main(void) {
-    unsigned char msg[12] = "Hello World!";
+    unsigned char msg[] = {'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd', '!'};
     unsigned char msg_hash[32];
-    unsigned char tag[17] = "my_fancy_protocol";
+    unsigned char tag[] = {'m', 'y', '_', 'f', 'a', 'n', 'c', 'y', '_', 'p', 'r', 'o', 't', 'o', 'c', 'o', 'l'};
     unsigned char seckey[32];
     unsigned char randomize[32];
     unsigned char auxiliary_rand[32];

src/secp256k1/include/secp256k1_ellswift.h

@@ -35,7 +35,7 @@ extern "C" {
  *
  * If the Y coordinate is relevant, it is given the same parity as t.
  *
- * Changes w.r.t. the the paper:
+ * Changes w.r.t. the paper:
  * - The u=0, t=0, and u^3+t^2+7=0 conditions result in decoding to the point
  *   at infinity in the paper. Here they are remapped to finite points.
  * - The paper uses an additional encoding bit for the parity of y. Here the

src/secp256k1/src/modules/ellswift/tests_impl.h

@@ -406,9 +406,9 @@ void run_ellswift_tests(void) {
     /* Test hash initializers. */
     {
         secp256k1_sha256 sha, sha_optimized;
-        static const unsigned char encode_tag[25] = "secp256k1_ellswift_encode";
-        static const unsigned char create_tag[25] = "secp256k1_ellswift_create";
-        static const unsigned char bip324_tag[26] = "bip324_ellswift_xonly_ecdh";
+        static const unsigned char encode_tag[] = {'s', 'e', 'c', 'p', '2', '5', '6', 'k', '1', '_', 'e', 'l', 'l', 's', 'w', 'i', 'f', 't', '_', 'e', 'n', 'c', 'o', 'd', 'e'};
+        static const unsigned char create_tag[] = {'s', 'e', 'c', 'p', '2', '5', '6', 'k', '1', '_', 'e', 'l', 'l', 's', 'w', 'i', 'f', 't', '_', 'c', 'r', 'e', 'a', 't', 'e'};
+        static const unsigned char bip324_tag[] = {'b', 'i', 'p', '3', '2', '4', '_', 'e', 'l', 'l', 's', 'w', 'i', 'f', 't', '_', 'x', 'o', 'n', 'l', 'y', '_', 'e', 'c', 'd', 'h'};
 
         /* Check that hash initialized by
          * secp256k1_ellswift_sha256_init_encode has the expected

src/secp256k1/src/modules/schnorrsig/main_impl.h

@@ -45,7 +45,7 @@ static void secp256k1_nonce_function_bip340_sha256_tagged_aux(secp256k1_sha256 *
 
 /* algo argument for nonce_function_bip340 to derive the nonce exactly as stated in BIP-340
  * by using the correct tagged hash function. */
-static const unsigned char bip340_algo[13] = "BIP0340/nonce";
+static const unsigned char bip340_algo[] = {'B', 'I', 'P', '0', '3', '4', '0', '/', 'n', 'o', 'n', 'c', 'e'};
 
 static const unsigned char schnorrsig_extraparams_magic[4] = SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC;
 

src/secp256k1/src/modules/schnorrsig/tests_impl.h

@@ -21,9 +21,9 @@ static void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, s
 }
 
 static void run_nonce_function_bip340_tests(void) {
-    unsigned char tag[13] = "BIP0340/nonce";
-    unsigned char aux_tag[11] = "BIP0340/aux";
-    unsigned char algo[13] = "BIP0340/nonce";
+    unsigned char tag[] = {'B', 'I', 'P', '0', '3', '4', '0', '/', 'n', 'o', 'n', 'c', 'e'};
+    unsigned char aux_tag[] = {'B', 'I', 'P', '0', '3', '4', '0', '/', 'a', 'u', 'x'};
+    unsigned char algo[] = {'B', 'I', 'P', '0', '3', '4', '0', '/', 'n', 'o', 'n', 'c', 'e'};
     size_t algolen = sizeof(algo);
     secp256k1_sha256 sha;
     secp256k1_sha256 sha_optimized;
@@ -158,7 +158,7 @@ static void test_schnorrsig_api(void) {
 /* Checks that hash initialized by secp256k1_schnorrsig_sha256_tagged has the
  * expected state. */
 static void test_schnorrsig_sha256_tagged(void) {
-    unsigned char tag[17] = "BIP0340/challenge";
+    unsigned char tag[] = {'B', 'I', 'P', '0', '3', '4', '0', '/', 'c', 'h', 'a', 'l', 'l', 'e', 'n', 'g', 'e'};
     secp256k1_sha256 sha;
     secp256k1_sha256 sha_optimized;
 
@@ -806,7 +806,7 @@ static void test_schnorrsig_sign(void) {
     unsigned char sk[32];
     secp256k1_xonly_pubkey pk;
     secp256k1_keypair keypair;
-    const unsigned char msg[32] = "this is a msg for a schnorrsig..";
+    const unsigned char msg[] = {'t', 'h', 'i', 's', ' ', 'i', 's', ' ', 'a', ' ', 'm', 's', 'g', ' ', 'f', 'o', 'r', ' ', 'a', ' ', 's', 'c', 'h', 'n', 'o', 'r', 'r', 's', 'i', 'g', '.', '.'};
     unsigned char sig[64];
     unsigned char sig2[64];
     unsigned char zeros64[64] = { 0 };

src/secp256k1/src/testrand_impl.h

@@ -18,7 +18,7 @@
 static uint64_t secp256k1_test_state[4];
 
 SECP256K1_INLINE static void testrand_seed(const unsigned char *seed16) {
-    static const unsigned char PREFIX[19] = "secp256k1 test init";
+    static const unsigned char PREFIX[] = {'s', 'e', 'c', 'p', '2', '5', '6', 'k', '1', ' ', 't', 'e', 's', 't', ' ', 'i', 'n', 'i', 't'};
     unsigned char out32[32];
     secp256k1_sha256 hash;
     int i;