1 files changed, 69 insertions, 0 deletions
diff --git a/src/wsgcrypt.cpp b/src/wsgcrypt.cpp
new file mode 100644
index 0000000..c6b89a5
--- /dev/null
+++ b/src/wsgcrypt.cpp
@@ -0,0 +1,69 @@
+/**
+ * wsgcrypt.c
+ *
+ * Created on 2020-11-26
+ * @author: qyc
+ *
+ * @explain: 
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "wsgcrypt.h"
+
+gcry_error_t ws_hmac_buffer(int algo, void *digest, const void *buffer, size_t length, const void *key, size_t keylen)
+{
+	gcry_md_hd_t hmac_handle;
+	gcry_error_t result = gcry_md_open(&hmac_handle, algo, GCRY_MD_FLAG_HMAC);
+	if (result) {
+		return result;
+	}
+	result = gcry_md_setkey(hmac_handle, key, keylen);
+	if (result) {
+		gcry_md_close(hmac_handle);
+		return result;
+	}
+	gcry_md_write(hmac_handle, buffer, length);
+	memcpy(digest, gcry_md_read(hmac_handle, 0), gcry_md_get_algo_dlen(algo));
+	gcry_md_close(hmac_handle);
+	return GPG_ERR_NO_ERROR;
+}
+
+gcry_error_t hkdf_expand(int hashalgo, const guint8 *prk, guint prk_len, const guint8 *info, guint info_len, guint8 *out, guint out_len)
+{
+	// Current maximum hash output size: 48 bytes for SHA-384.
+	guchar lastoutput[48];
+	gcry_md_hd_t h;
+	gcry_error_t err;
+	const guint hash_len = gcry_md_get_algo_dlen(hashalgo);
+
+	// Some sanity checks
+	if (!(out_len > 0 && out_len <= 255 * hash_len) || !(hash_len > 0 && hash_len <= sizeof(lastoutput)))
+		return GPG_ERR_INV_ARG;
+
+	err = gcry_md_open(&h, hashalgo, GCRY_MD_FLAG_HMAC);
+	if (err)
+		return err;
+	
+	guint offset;
+	for (offset = 0; offset < out_len; offset += hash_len) {
+		gcry_md_reset(h);
+		// Set PRK
+		gcry_md_setkey(h, prk, prk_len);
+		if (offset > 0)
+			// T(1..N)
+			gcry_md_write(h, lastoutput, hash_len);
+		// info
+		gcry_md_write(h, info, info_len);
+		// constant 0x01..N
+		gcry_md_putc(h, (guint8)(offset / hash_len + 1));
+
+		memcpy(lastoutput, gcry_md_read(h, hashalgo), hash_len);
+		memcpy(out + offset, lastoutput, MIN(hash_len, out_len - offset));
+	}
+
+	gcry_md_close(h);
+
+	return 0;
+}