crypto/hmac_sha256: add partial progress functions.

[ccan] / ccan / crypto / hmac_sha256 / hmac_sha256.h

diff --git a/ccan/crypto/hmac_sha256/hmac_sha256.h b/ccan/crypto/hmac_sha256/hmac_sha256.h
index 2ddcbe32619a8248a7150f0eb930aa3e20a38c7d..79f1660cdfe75e0dfd35ce8ee47d6ed1fa5584ef 100644 (file)
--- a/ccan/crypto/hmac_sha256/hmac_sha256.h
+++ b/ccan/crypto/hmac_sha256/hmac_sha256.h
@@ -6,12 +6,8 @@
 #include <stdlib.h>
 #include <ccan/crypto/sha256/sha256.h>
 
-/* Uncomment this to use openssl's HMAC routines (and link with -lcrypto) */
-/*#define CCAN_CRYPTO_HMAC_USE_OPENSSL 1*/
-
-#ifdef CCAN_CRYPTO_HMAC_USE_OPENSSL
-#include <openssl/hmac.h>
-#endif
+/* Number of bytes per block. */
+#define HMAC_SHA256_BLOCKSIZE 64
 
 /**
  * struct hmac_sha256 - structure representing a completed HMAC.
@@ -31,4 +27,60 @@ struct hmac_sha256 {
 void hmac_sha256(struct hmac_sha256 *hmac,
                 const void *k, size_t ksize,
                 const void *d, size_t dsize);
+
+/**
+ * struct hmac_sha256_ctx - structure to store running context for hmac_sha256
+ */
+struct hmac_sha256_ctx {
+       struct sha256_ctx sha;
+       uint64_t k_opad[HMAC_SHA256_BLOCKSIZE / sizeof(uint64_t)];
+};
+
+/**
+ * hmac_sha256_init - initialize an HMAC_SHA256 context.
+ * @ctx: the hmac_sha256_ctx to initialize
+ * @k: pointer to the key,
+ * @ksize: the number of bytes pointed to by @k
+ *
+ * This must be called before hmac_sha256_update or hmac_sha256_done.
+ *
+ * If it was already initialized, this forgets anything which was
+ * hashed before.
+ *
+ * Example:
+ * static void hmac_all(const char *key,
+ *                     const char **arr, struct hmac_sha256 *hash)
+ * {
+ *     size_t i;
+ *     struct hmac_sha256_ctx ctx;
+ *
+ *     hmac_sha256_init(&ctx, key, strlen(key));
+ *     for (i = 0; arr[i]; i++)
+ *             hmac_sha256_update(&ctx, arr[i], strlen(arr[i]));
+ *     hmac_sha256_done(&ctx, hash);
+ * }
+ */
+void hmac_sha256_init(struct hmac_sha256_ctx *ctx,
+                     const void *k, size_t ksize);
+
+/**
+ * hmac_sha256_update - include some memory in the hash.
+ * @ctx: the hmac_sha256_ctx to use
+ * @p: pointer to memory,
+ * @size: the number of bytes pointed to by @p
+ *
+ * You can call this multiple times to hash more data, before calling
+ * hmac_sha256_done().
+ */
+void hmac_sha256_update(struct hmac_sha256_ctx *ctx, const void *p, size_t size);
+
+/**
+ * hmac_sha256_done - finish HMAC_SHA256 and return the hash
+ * @ctx: the hmac_sha256_ctx to complete
+ * @res: the hash to return.
+ *
+ * Note that @ctx is *destroyed* by this, and must be reinitialized.
+ * To avoid that, pass a copy instead.
+ */
+void hmac_sha256_done(struct hmac_sha256_ctx *hmac_sha256, struct hmac_sha256 *res);
 #endif /* CCAN_CRYPTO_HMAC_SHA256_H */