tkey-libs: Import tag fw-4 of tkey-libs

- Use tag fw-4 from https://github.com/tillitis/tkey-libs/

hw/application_fpga/tkey-libs/blake2s/blake2s.h

@@ -0,0 +1,45 @@
+//======================================================================
+//
+// blake2s.h
+// ---------
+// BLAKE2s Hashing Context and API Prototypes
+//
+// See LICENSE for license terms.
+// See README.md in the repo root for info about source code origin.
+//======================================================================
+
+#ifndef BLAKE2S_H
+#define BLAKE2S_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+// state context
+typedef struct {
+    uint8_t b[64];                      // input buffer
+    uint32_t h[8];                      // chained state
+    uint32_t t[2];                      // total number of bytes
+    size_t c;                           // pointer for b[]
+    size_t outlen;                      // digest size
+} blake2s_ctx;
+
+// Initialize the hashing context "ctx" with optional key "key".
+//      1 <= outlen <= 32 gives the digest size in bytes.
+//      Secret key (also <= 32 bytes) is optional (keylen = 0).
+int blake2s_init(blake2s_ctx *ctx, size_t outlen,
+    const void *key, size_t keylen);    // secret key
+
+// Add "inlen" bytes from "in" into the hash.
+void blake2s_update(blake2s_ctx *ctx,   // context
+    const void *in, size_t inlen);      // data to be hashed
+
+// Generate the message digest (size given in init).
+//      Result placed in "out".
+void blake2s_final(blake2s_ctx *ctx, void *out);
+
+// All-in-one convenience function.
+int blake2s(void *out, size_t outlen,   // return buffer for digest
+    const void *key, size_t keylen,     // optional secret key
+    const void *in, size_t inlen);      // data to be hashed
+
+#endif