tool: Introduce b2s tool to help compute BLAKE2s digests

hw/application_fpga/tools/b2s/b2s.go

@@ -0,0 +1,59 @@
+// SPDX-FileCopyrightText: 2025 Tillitis AB <tillitis.se>
+// SPDX-License-Identifier: BSD-2-Clause
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"golang.org/x/crypto/blake2s"
+)
+
+func usage() {
+	fmt.Printf("Usage: %s -m filename [-c]\n", os.Args[0])
+}
+
+func printCDigest(digest [blake2s.Size]byte, fileName string) {
+	fmt.Printf("// BLAKE2s digest of %v\n", fileName)
+	fmt.Printf("const uint8_t digest[32] = {\n")
+
+	for _, n := range digest {
+		fmt.Printf("0x%x, ", n)
+	}
+
+	fmt.Printf("\n}; \n")
+}
+
+func main() {
+	var messageFile string
+	var forC bool
+
+	flag.StringVar(&messageFile, "m", "", "Specify file containing message.")
+	flag.BoolVar(&forC, "c", false, "Print digest for inclusion in C program.")
+
+	flag.Usage = usage
+	flag.Parse()
+
+	if messageFile == "" {
+		usage()
+		os.Exit(0)
+	}
+
+	message, err := os.ReadFile(messageFile)
+	if err != nil {
+		fmt.Printf("%v\n", err)
+		os.Exit(1)
+	}
+
+	digest := blake2s.Sum256(message)
+
+	if forC {
+		printCDigest(digest, messageFile)
+	} else {
+		fmt.Printf("%x %s\n", digest, messageFile)
+	}
+
+	os.Exit(0)
+}