diff -ur a/builtin/receive-pack.c b/builtin/receive-pack.c
--- a/builtin/receive-pack.c	2020-06-01 17:49:27.000000000 +0200
+++ b/builtin/receive-pack.c	2020-06-15 15:28:48.149268576 +0200
@@ -29,6 +29,8 @@
 #include "commit-reach.h"
 #include "worktree.h"
 #include "shallow.h"
+#include <openssl/hmac.h>	
+#include <openssl/evp.h>
 
 static const char * const receive_pack_usage[] = {
 	N_("git receive-pack <git-dir>"),
@@ -419,43 +421,11 @@
 	return 0;
 }
 
-static void hmac_hash(unsigned char *out,
+static inline void hmac_hash(unsigned char *out,
 		      const char *key_in, size_t key_len,
 		      const char *text, size_t text_len)
 {
-	unsigned char key[GIT_MAX_BLKSZ];
-	unsigned char k_ipad[GIT_MAX_BLKSZ];
-	unsigned char k_opad[GIT_MAX_BLKSZ];
-	int i;
-	git_hash_ctx ctx;
-
-	/* RFC 2104 2. (1) */
-	memset(key, '\0', GIT_MAX_BLKSZ);
-	if (the_hash_algo->blksz < key_len) {
-		the_hash_algo->init_fn(&ctx);
-		the_hash_algo->update_fn(&ctx, key_in, key_len);
-		the_hash_algo->final_fn(key, &ctx);
-	} else {
-		memcpy(key, key_in, key_len);
-	}
-
-	/* RFC 2104 2. (2) & (5) */
-	for (i = 0; i < sizeof(key); i++) {
-		k_ipad[i] = key[i] ^ 0x36;
-		k_opad[i] = key[i] ^ 0x5c;
-	}
-
-	/* RFC 2104 2. (3) & (4) */
-	the_hash_algo->init_fn(&ctx);
-	the_hash_algo->update_fn(&ctx, k_ipad, sizeof(k_ipad));
-	the_hash_algo->update_fn(&ctx, text, text_len);
-	the_hash_algo->final_fn(out, &ctx);
-
-	/* RFC 2104 2. (6) & (7) */
-	the_hash_algo->init_fn(&ctx);
-	the_hash_algo->update_fn(&ctx, k_opad, sizeof(k_opad));
-	the_hash_algo->update_fn(&ctx, out, the_hash_algo->rawsz);
-	the_hash_algo->final_fn(out, &ctx);
+	HMAC(EVP_sha1(), key_in, key_len, text, text_len, out, NULL);
 }
 
 static char *prepare_push_cert_nonce(const char *path, timestamp_t stamp)
diff -ur a/Makefile b/Makefile
--- a/Makefile	2020-06-01 17:49:27.000000000 +0200
+++ b/Makefile	2020-06-15 15:00:45.212758547 +0200
@@ -1830,6 +1830,8 @@
 	BASIC_CFLAGS += -DHAVE_GETDELIM
 endif
 
+EXTLIBS += -lcrypto
+
 ifneq ($(PROCFS_EXECUTABLE_PATH),)
 	procfs_executable_path_SQ = $(subst ','\'',$(PROCFS_EXECUTABLE_PATH))
 	BASIC_CFLAGS += '-DPROCFS_EXECUTABLE_PATH="$(procfs_executable_path_SQ)"'