# HG changeset patch
# User Florian Zeitz <florob@babelmonkeys.de>
# Date 1346280236 -7200
# Node ID e2f682fab829c2ef23a050f884191f57e2fb5d60
# Parent  9bc2e718392ceaa327f14b50163232b629cd54d1
lib: Generalize hmac to be hash independent

diff --git a/src/auth/mech-cram-md5.c b/src/auth/mech-cram-md5.c
--- a/src/auth/mech-cram-md5.c
+++ b/src/auth/mech-cram-md5.c
@@ -7,7 +7,9 @@
 #include "ioloop.h"
 #include "buffer.h"
 #include "hex-binary.h"
-#include "hmac-md5.h"
+#include "hmac-cram-md5.h"
+#include "hmac.h"
+#include "md5.h"
 #include "randgen.h"
 #include "mech.h"
 #include "passdb.h"
@@ -50,7 +52,7 @@
 {
 	
 	unsigned char digest[MD5_RESULTLEN];
-        struct hmac_md5_context ctx;
+        struct hmac_context ctx;
 	const char *response_hex;
 
 	if (size != CRAM_MD5_CONTEXTLEN) {
@@ -59,9 +61,10 @@
 		return FALSE;
 	}
 
+	hmac_init(&ctx, NULL, 0, &hash_method_md5);
 	hmac_md5_set_cram_context(&ctx, credentials);
-	hmac_md5_update(&ctx, request->challenge, strlen(request->challenge));
-	hmac_md5_final(&ctx, digest);
+	hmac_update(&ctx, request->challenge, strlen(request->challenge));
+	hmac_final(&ctx, digest);
 
 	response_hex = binary_to_hex(digest, sizeof(digest));
 
diff --git a/src/auth/mech-scram-sha1.c b/src/auth/mech-scram-sha1.c
--- a/src/auth/mech-scram-sha1.c
+++ b/src/auth/mech-scram-sha1.c
@@ -9,7 +9,8 @@
 #include "auth-common.h"
 #include "base64.h"
 #include "buffer.h"
-#include "hmac-sha1.h"
+#include "hmac.h"
+#include "sha1.h"
 #include "randgen.h"
 #include "safe-memset.h"
 #include "str.h"
@@ -44,23 +45,23 @@
 	       const unsigned char *salt, size_t salt_size, unsigned int i,
 	       unsigned char result[SHA1_RESULTLEN])
 {
-	struct hmac_sha1_context ctx;
+	struct hmac_context ctx;
 	unsigned char U[SHA1_RESULTLEN];
 	unsigned int j, k;
 
 	/* Calculate U1 */
-	hmac_sha1_init(&ctx, str, str_size);
-	hmac_sha1_update(&ctx, salt, salt_size);
-	hmac_sha1_update(&ctx, "\0\0\0\1", 4);
-	hmac_sha1_final(&ctx, U);
+	hmac_init(&ctx, str, str_size, &hash_method_sha1);
+	hmac_update(&ctx, salt, salt_size);
+	hmac_update(&ctx, "\0\0\0\1", 4);
+	hmac_final(&ctx, U);
 
 	memcpy(result, U, SHA1_RESULTLEN);
 
 	/* Calculate U2 to Ui and Hi */
 	for (j = 2; j <= i; j++) {
-		hmac_sha1_init(&ctx, str, str_size);
-		hmac_sha1_update(&ctx, U, sizeof(U));
-		hmac_sha1_final(&ctx, U);
+		hmac_init(&ctx, str, str_size, &hash_method_sha1);
+		hmac_update(&ctx, U, sizeof(U));
+		hmac_final(&ctx, U);
 		for (k = 0; k < SHA1_RESULTLEN; k++)
 			result[k] ^= U[k];
 	}
@@ -94,7 +95,7 @@
 
 static const char *get_scram_server_final(struct scram_auth_request *request)
 {
-	struct hmac_sha1_context ctx;
+	struct hmac_context ctx;
 	const char *auth_message;
 	unsigned char server_key[SHA1_RESULTLEN];
 	unsigned char server_signature[SHA1_RESULTLEN];
@@ -104,17 +105,17 @@
 			request->server_first_message, ",",
 			request->client_final_message_without_proof, NULL);
 
-	hmac_sha1_init(&ctx, request->salted_password,
-		       sizeof(request->salted_password));
-	hmac_sha1_update(&ctx, "Server Key", 10);
-	hmac_sha1_final(&ctx, server_key);
+	hmac_init(&ctx, request->salted_password,
+		  sizeof(request->salted_password), &hash_method_sha1);
+	hmac_update(&ctx, "Server Key", 10);
+	hmac_final(&ctx, server_key);
 
 	safe_memset(request->salted_password, 0,
 		    sizeof(request->salted_password));
 
-	hmac_sha1_init(&ctx, server_key, sizeof(server_key));
-	hmac_sha1_update(&ctx, auth_message, strlen(auth_message));
-	hmac_sha1_final(&ctx, server_signature);
+	hmac_init(&ctx, server_key, sizeof(server_key), &hash_method_sha1);
+	hmac_update(&ctx, auth_message, strlen(auth_message));
+	hmac_final(&ctx, server_signature);
 
 	str = t_str_new(MAX_BASE64_ENCODED_SIZE(sizeof(server_signature)));
 	str_append(str, "v=");
@@ -213,7 +214,7 @@
 static bool verify_credentials(struct scram_auth_request *request,
 			       const unsigned char *credentials, size_t size)
 {
-	struct hmac_sha1_context ctx;
+	struct hmac_context ctx;
 	const char *auth_message;
 	unsigned char client_key[SHA1_RESULTLEN];
 	unsigned char client_signature[SHA1_RESULTLEN];
@@ -224,10 +225,10 @@
 	Hi(credentials, size, request->salt, sizeof(request->salt),
 	   SCRAM_ITERATE_COUNT, request->salted_password);
 
-	hmac_sha1_init(&ctx, request->salted_password,
-			sizeof(request->salted_password));
-	hmac_sha1_update(&ctx, "Client Key", 10);
-	hmac_sha1_final(&ctx, client_key);
+	hmac_init(&ctx, request->salted_password,
+		  sizeof(request->salted_password), &hash_method_sha1);
+	hmac_update(&ctx, "Client Key", 10);
+	hmac_final(&ctx, client_key);
 
 	sha1_get_digest(client_key, sizeof(client_key), stored_key);
 
@@ -235,9 +236,9 @@
 			request->server_first_message, ",",
 			request->client_final_message_without_proof, NULL);
 
-	hmac_sha1_init(&ctx, stored_key, sizeof(stored_key));
-	hmac_sha1_update(&ctx, auth_message, strlen(auth_message));
-	hmac_sha1_final(&ctx, client_signature);
+	hmac_init(&ctx, stored_key, sizeof(stored_key), &hash_method_sha1);
+	hmac_update(&ctx, auth_message, strlen(auth_message));
+	hmac_final(&ctx, client_signature);
 
 	for (i = 0; i < sizeof(client_signature); i++)
 		client_signature[i] ^= client_key[i];
diff --git a/src/auth/password-scheme.c b/src/auth/password-scheme.c
--- a/src/auth/password-scheme.c
+++ b/src/auth/password-scheme.c
@@ -6,7 +6,8 @@
 #include "hex-binary.h"
 #include "md4.h"
 #include "md5.h"
-#include "hmac-md5.h"
+#include "hmac.h"
+#include "hmac-cram-md5.h"
 #include "ntlm.h"
 #include "mycrypt.h"
 #include "randgen.h"
@@ -655,12 +656,12 @@
 cram_md5_generate(const char *plaintext, const char *user ATTR_UNUSED,
 		  const unsigned char **raw_password_r, size_t *size_r)
 {
-	struct hmac_md5_context ctx;
+	struct hmac_context ctx;
 	unsigned char *context_digest;
 
 	context_digest = t_malloc(CRAM_MD5_CONTEXTLEN);
-	hmac_md5_init(&ctx, (const unsigned char *)plaintext,
-		      strlen(plaintext));
+	hmac_init(&ctx, (const unsigned char *)plaintext,
+		  strlen(plaintext), &hash_method_md5);
 	hmac_md5_get_cram_context(&ctx, context_digest);
 
 	*raw_password_r = context_digest;
diff --git a/src/lib-ntlm/ntlm-encrypt.c b/src/lib-ntlm/ntlm-encrypt.c
--- a/src/lib-ntlm/ntlm-encrypt.c
+++ b/src/lib-ntlm/ntlm-encrypt.c
@@ -11,7 +11,8 @@
 #include "compat.h"
 #include "safe-memset.h"
 #include "md4.h"
-#include "hmac-md5.h"
+#include "md5.h"
+#include "hmac.h"
 #include "ntlm.h"
 #include "ntlm-des.h"
 
@@ -60,12 +61,12 @@
 }
 
 static void
-hmac_md5_ucs2le_string_ucase(struct hmac_md5_context *ctx, const char *str)
+hmac_md5_ucs2le_string_ucase(struct hmac_context *ctx, const char *str)
 {
 	size_t len;
 	unsigned char *wstr = t_unicode_str(str, 1, &len);
 
-	hmac_md5_update(ctx, wstr, len);
+	hmac_update(ctx, wstr, len);
 }
 
 static void ATTR_NULL(2)
@@ -73,13 +74,13 @@
 	     const unsigned char *hash_v1,
 	     unsigned char hash[NTLMSSP_V2_HASH_SIZE])
 {
-	struct hmac_md5_context ctx;
+	struct hmac_context ctx;
 
-	hmac_md5_init(&ctx, hash_v1, NTLMSSP_HASH_SIZE);
+	hmac_init(&ctx, hash_v1, NTLMSSP_HASH_SIZE, &hash_method_md5);
 	hmac_md5_ucs2le_string_ucase(&ctx, user);
 	if (target != NULL)
 		hmac_md5_ucs2le_string_ucase(&ctx, target);
-	hmac_md5_final(&ctx, hash);
+	hmac_final(&ctx, hash);
 }
 
 void
@@ -124,15 +125,15 @@
 		    const unsigned char *blob, size_t blob_size,
 		    unsigned char response[NTLMSSP_V2_RESPONSE_SIZE])
 {
-	struct hmac_md5_context ctx;
+	struct hmac_context ctx;
 	unsigned char hash[NTLMSSP_V2_HASH_SIZE];
 
 	ntlm_v2_hash(user, target, hash_v1, hash);
 
-	hmac_md5_init(&ctx, hash, NTLMSSP_V2_HASH_SIZE);
-	hmac_md5_update(&ctx, challenge, NTLMSSP_CHALLENGE_SIZE);
-	hmac_md5_update(&ctx, blob, blob_size);
-	hmac_md5_final(&ctx, response);
+	hmac_init(&ctx, hash, NTLMSSP_V2_HASH_SIZE, &hash_method_md5);
+	hmac_update(&ctx, challenge, NTLMSSP_CHALLENGE_SIZE);
+	hmac_update(&ctx, blob, blob_size);
+	hmac_final(&ctx, response);
 
 	safe_memset(hash, 0, sizeof(hash));
 }
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -44,8 +44,8 @@
 	hash2.c \
 	hex-binary.c \
 	hex-dec.c \
-	hmac-md5.c \
-	hmac-sha1.c \
+	hmac.c \
+	hmac-cram-md5.c \
 	home-expand.c \
 	hostpid.c \
 	imem.c \
@@ -170,8 +170,8 @@
 	hash2.h \
 	hex-binary.h \
 	hex-dec.h \
-	hmac-md5.h \
-	hmac-sha1.h \
+	hmac.h \
+	hmac-cram-md5.h \
 	home-expand.h \
 	hostpid.h \
 	imem.h \
diff --git a/src/lib/hmac-cram-md5.c b/src/lib/hmac-cram-md5.c
new file mode 100644
--- /dev/null
+++ b/src/lib/hmac-cram-md5.c
@@ -0,0 +1,64 @@
+/*
+ * CRAM-MD5 (RFC 2195) compatibility code
+ * Copyright (c) 2003 Joshua Goodall <joshua@roughtrade.net>
+ *
+ * This software is released under the MIT license.
+ */
+
+#include "lib.h"
+#include "md5.h"
+#include "hmac.h"
+#include "hmac-cram-md5.h"
+
+void hmac_md5_get_cram_context(struct hmac_context *hmac_ctx,
+			unsigned char context_digest[CRAM_MD5_CONTEXTLEN])
+{
+	unsigned char *cdp;
+
+	struct md5_context *ctx = hmac_ctx->ctx;
+	struct md5_context *ctxo = hmac_ctx->ctxo;
+
+#define CDPUT(p, c) STMT_START {   \
+	*(p)++ = (c) & 0xff;       \
+	*(p)++ = (c) >> 8 & 0xff;  \
+	*(p)++ = (c) >> 16 & 0xff; \
+	*(p)++ = (c) >> 24 & 0xff; \
+} STMT_END
+	cdp = context_digest;
+	CDPUT(cdp, ctxo->a);
+	CDPUT(cdp, ctxo->b);
+	CDPUT(cdp, ctxo->c);
+	CDPUT(cdp, ctxo->d);
+	CDPUT(cdp, ctx->a);
+	CDPUT(cdp, ctx->b);
+	CDPUT(cdp, ctx->c);
+	CDPUT(cdp, ctx->d);
+}
+
+void hmac_md5_set_cram_context(struct hmac_context *hmac_ctx,
+			const unsigned char context_digest[CRAM_MD5_CONTEXTLEN])
+{
+	const unsigned char *cdp;
+
+	struct md5_context *ctx = hmac_ctx->ctx;
+	struct md5_context *ctxo = hmac_ctx->ctxo;
+
+#define CDGET(p, c) STMT_START { \
+	(c)  = (*p++);           \
+	(c) += (*p++ << 8);      \
+	(c) += (*p++ << 16);     \
+	(c) += (*p++ << 24);     \
+} STMT_END
+	cdp = context_digest;
+	CDGET(cdp, ctxo->a);
+	CDGET(cdp, ctxo->b);
+	CDGET(cdp, ctxo->c);
+	CDGET(cdp, ctxo->d);
+	CDGET(cdp, ctx->a);
+	CDGET(cdp, ctx->b);
+	CDGET(cdp, ctx->c);
+	CDGET(cdp, ctx->d);
+
+	ctxo->lo = ctx->lo = 64;
+	ctxo->hi = ctx->hi = 0;
+}
diff --git a/src/lib/hmac-cram-md5.h b/src/lib/hmac-cram-md5.h
new file mode 100644
--- /dev/null
+++ b/src/lib/hmac-cram-md5.h
@@ -0,0 +1,12 @@
+#ifndef HMAC_CRAM_MD5_H
+#define HMAC_CRAM_MD5_H
+
+#define CRAM_MD5_CONTEXTLEN 32
+
+void hmac_md5_get_cram_context(struct hmac_context *ctx,
+		unsigned char context_digest[CRAM_MD5_CONTEXTLEN]);
+void hmac_md5_set_cram_context(struct hmac_context *ctx,
+		const unsigned char context_digest[CRAM_MD5_CONTEXTLEN]);
+
+
+#endif
diff --git a/src/lib/hmac-md5.c b/src/lib/hmac-md5.c
deleted file mode 100644
--- a/src/lib/hmac-md5.c
+++ /dev/null
@@ -1,101 +0,0 @@
-/*
- * HMAC-MD5 (RFC-2104) implementation.
- *
- * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
- *
- * CRAM-MD5 (RFC 2195) compatibility code
- * Copyright (c) 2003 Joshua Goodall <joshua@roughtrade.net>
- *
- * This software is released under the MIT license.
- */
-
-#include "lib.h"
-#include "hmac-md5.h"
-#include "safe-memset.h"
-
-void hmac_md5_init(struct hmac_md5_context *ctx,
-		   const unsigned char *key, size_t key_len)
-{
-	int i;
-	unsigned char md5key[16];
-	unsigned char k_ipad[64];
-	unsigned char k_opad[64];
-
-	if (key_len > 64) {
-		md5_get_digest(key, key_len, md5key);
-		key = md5key;
-		key_len = 16;
-	}
-
-	memcpy(k_ipad, key, key_len);
-	memset(k_ipad + key_len, 0, 64 - key_len);
-	memcpy(k_opad, k_ipad, 64);
-
-	for (i = 0; i < 64; i++) {
-		k_ipad[i] ^= 0x36;
-		k_opad[i] ^= 0x5c;
-	}
-
-	md5_init(&ctx->ctx);
-	md5_update(&ctx->ctx, k_ipad, 64);  
-	md5_init(&ctx->ctxo);
-	md5_update(&ctx->ctxo, k_opad, 64);   
-
-	safe_memset(k_ipad, 0, 64);
-	safe_memset(k_opad, 0, 64);
-}
-
-void hmac_md5_final(struct hmac_md5_context *ctx, unsigned char *digest)
-{
-	md5_final(&ctx->ctx, digest);
-
-	md5_update(&ctx->ctxo, digest, 16); 
-	md5_final(&ctx->ctxo, digest);
-}
-
-void hmac_md5_get_cram_context(struct hmac_md5_context *ctx,
-			unsigned char context_digest[CRAM_MD5_CONTEXTLEN])
-{
-	unsigned char *cdp;
-
-#define CDPUT(p, c) STMT_START {   \
-	*(p)++ = (c) & 0xff;       \
-	*(p)++ = (c) >> 8 & 0xff;  \
-	*(p)++ = (c) >> 16 & 0xff; \
-	*(p)++ = (c) >> 24 & 0xff; \
-} STMT_END
-	cdp = context_digest;
-	CDPUT(cdp, ctx->ctxo.a);
-	CDPUT(cdp, ctx->ctxo.b);
-	CDPUT(cdp, ctx->ctxo.c);
-	CDPUT(cdp, ctx->ctxo.d);
-	CDPUT(cdp, ctx->ctx.a);
-	CDPUT(cdp, ctx->ctx.b);
-	CDPUT(cdp, ctx->ctx.c);
-	CDPUT(cdp, ctx->ctx.d);
-}
-
-void hmac_md5_set_cram_context(struct hmac_md5_context *ctx,
-			const unsigned char context_digest[CRAM_MD5_CONTEXTLEN])
-{
-	const unsigned char *cdp;
-
-#define CDGET(p, c) STMT_START { \
-	(c)  = (*p++);           \
-	(c) += (*p++ << 8);      \
-	(c) += (*p++ << 16);     \
-	(c) += (*p++ << 24);     \
-} STMT_END
-	cdp = context_digest;
-	CDGET(cdp, ctx->ctxo.a);
-	CDGET(cdp, ctx->ctxo.b);
-	CDGET(cdp, ctx->ctxo.c);
-	CDGET(cdp, ctx->ctxo.d);
-	CDGET(cdp, ctx->ctx.a);
-	CDGET(cdp, ctx->ctx.b);
-	CDGET(cdp, ctx->ctx.c);
-	CDGET(cdp, ctx->ctx.d);
-
-	ctx->ctxo.lo = ctx->ctx.lo = 64;
-	ctx->ctxo.hi = ctx->ctx.hi = 0;
-}
diff --git a/src/lib/hmac-md5.h b/src/lib/hmac-md5.h
deleted file mode 100644
--- a/src/lib/hmac-md5.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#ifndef HMAC_MD5_H
-#define HMAC_MD5_H
-
-#include "md5.h"
-
-#define CRAM_MD5_CONTEXTLEN 32
-
-struct hmac_md5_context {
-	struct md5_context ctx, ctxo;
-};
-
-void hmac_md5_init(struct hmac_md5_context *ctx,
-		   const unsigned char *key, size_t key_len);
-void hmac_md5_final(struct hmac_md5_context *ctx,
-		    unsigned char digest[MD5_RESULTLEN]);
-
-void hmac_md5_get_cram_context(struct hmac_md5_context *ctx,
-		unsigned char context_digest[CRAM_MD5_CONTEXTLEN]);
-void hmac_md5_set_cram_context(struct hmac_md5_context *ctx,
-		const unsigned char context_digest[CRAM_MD5_CONTEXTLEN]);
-
-
-static inline void
-hmac_md5_update(struct hmac_md5_context *ctx, const void *data, size_t size)
-{
-	md5_update(&ctx->ctx, data, size);
-}
-
-#endif
diff --git a/src/lib/hmac-sha1.c b/src/lib/hmac-sha1.c
deleted file mode 100644
--- a/src/lib/hmac-sha1.c
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * HMAC-SHA1 (RFC-2104) implementation.
- *
- * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
- * Copyright (c) 2011 Florian Zeitz <florob@babelmonkeys.de>
- *
- * This software is released under the MIT license.
- */
-
-#include "lib.h"
-#include "hmac-sha1.h"
-#include "safe-memset.h"
-
-void hmac_sha1_init(struct hmac_sha1_context *ctx,
-		   const unsigned char *key, size_t key_len)
-{
-	int i;
-	unsigned char sha1key[20];
-	unsigned char k_ipad[64];
-	unsigned char k_opad[64];
-
-	if (key_len > 64) {
-		sha1_get_digest(key, key_len, sha1key);
-		key = sha1key;
-		key_len = 20;
-	}
-
-	memcpy(k_ipad, key, key_len);
-	memset(k_ipad + key_len, 0, 64 - key_len);
-	memcpy(k_opad, k_ipad, 64);
-
-	for (i = 0; i < 64; i++) {
-		k_ipad[i] ^= 0x36;
-		k_opad[i] ^= 0x5c;
-	}
-
-	sha1_init(&ctx->ctx);
-	sha1_loop(&ctx->ctx, k_ipad, 64);
-	sha1_init(&ctx->ctxo);
-	sha1_loop(&ctx->ctxo, k_opad, 64);
-
-	safe_memset(k_ipad, 0, 64);
-	safe_memset(k_opad, 0, 64);
-}
-
-void hmac_sha1_final(struct hmac_sha1_context *ctx, unsigned char *digest)
-{
-	sha1_result(&ctx->ctx, digest);
-
-	sha1_loop(&ctx->ctxo, digest, 20);
-	sha1_result(&ctx->ctxo, digest);
-}
diff --git a/src/lib/hmac-sha1.h b/src/lib/hmac-sha1.h
deleted file mode 100644
--- a/src/lib/hmac-sha1.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#ifndef HMAC_SHA1_H
-#define HMAC_SHA1_H
-
-#include "sha1.h"
-
-struct hmac_sha1_context {
-	struct sha1_ctxt ctx, ctxo;
-};
-
-void hmac_sha1_init(struct hmac_sha1_context *ctx,
-		   const unsigned char *key, size_t key_len);
-void hmac_sha1_final(struct hmac_sha1_context *ctx,
-		    unsigned char digest[SHA1_RESULTLEN]);
-
-
-static inline void
-hmac_sha1_update(struct hmac_sha1_context *ctx, const void *data, size_t size)
-{
-	sha1_loop(&ctx->ctx, data, size);
-}
-
-#endif
diff --git a/src/lib/hmac.c b/src/lib/hmac.c
new file mode 100644
--- /dev/null
+++ b/src/lib/hmac.c
@@ -0,0 +1,58 @@
+/*
+ * HMAC (RFC-2104) implementation.
+ *
+ * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
+ * Copyright (c) 2011-2012 Florian Zeitz <florob@babelmonkeys.de>
+ *
+ * This software is released under the MIT license.
+ */
+
+#include "lib.h"
+#include "hmac.h"
+#include "safe-memset.h"
+
+void hmac_init(struct hmac_context *ctx, const unsigned char *key,
+		size_t key_len, const struct hash_method *meth)
+{
+	int i;
+	unsigned char k_ipad[64];
+	unsigned char k_opad[64];
+	unsigned char hashedkey[meth->digest_size];
+
+	ctx->hash = meth;
+	ctx->ctx = t_malloc(meth->context_size);
+	ctx->ctxo = t_malloc(meth->context_size);
+
+	if (key_len > 64) {
+		meth->init(ctx->ctx);
+		meth->loop(ctx->ctx, key, key_len);
+		meth->result(ctx->ctx, hashedkey);
+		key = hashedkey;
+		key_len = meth->digest_size;
+	}
+
+	memcpy(k_ipad, key, key_len);
+	memset(k_ipad + key_len, 0, 64 - key_len);
+	memcpy(k_opad, k_ipad, 64);
+
+	for (i = 0; i < 64; i++) {
+		k_ipad[i] ^= 0x36;
+		k_opad[i] ^= 0x5c;
+	}
+
+	meth->init(ctx->ctx);
+	meth->loop(ctx->ctx, k_ipad, 64);
+	meth->init(ctx->ctxo);
+	meth->loop(ctx->ctxo, k_opad, 64);
+
+	safe_memset(k_ipad, 0, 64);
+	safe_memset(k_opad, 0, 64);
+}
+
+void hmac_final(struct hmac_context *ctx, unsigned char *digest)
+{
+	ctx->hash->result(ctx->ctx, digest);
+
+	ctx->hash->loop(ctx->ctxo, digest, ctx->hash->digest_size);
+	ctx->hash->result(ctx->ctxo, digest);
+}
diff --git a/src/lib/hmac.h b/src/lib/hmac.h
new file mode 100644
--- /dev/null
+++ b/src/lib/hmac.h
@@ -0,0 +1,23 @@
+#ifndef HMAC_H
+#define HMAC_H
+
+#include "hash-method.h"
+#include "sha1.h"
+
+struct hmac_context {
+	void *ctx, *ctxo;
+	const struct hash_method *hash;
+};
+
+void hmac_init(struct hmac_context *ctx, const unsigned char *key,
+		size_t key_len, const struct hash_method *meth);
+void hmac_final(struct hmac_context *ctx, unsigned char *digest);
+
+
+static inline void
+hmac_update(struct hmac_context *ctx, const void *data, size_t size)
+{
+	ctx->hash->loop(ctx->ctx, data, size);
+}
+
+#endif