crypto/hmac_sha256: add partial progress functions.

[ccan] / ccan / crypto / hmac_sha256 / hmac_sha256.c

diff --git a/ccan/crypto/hmac_sha256/hmac_sha256.c b/ccan/crypto/hmac_sha256/hmac_sha256.c
index d252295521fe270ea72cfb0bfc21c75f66324c39..0392afe5c1127134e61e48d864dffe94252aeaa8 100644 (file)
--- a/ccan/crypto/hmac_sha256/hmac_sha256.c
+++ b/ccan/crypto/hmac_sha256/hmac_sha256.c
@@ -5,7 +5,7 @@
 #define IPAD 0x3636363636363636ULL
 #define OPAD 0x5C5C5C5C5C5C5C5CULL
 
-#define BLOCK_U64S (64 / sizeof(uint64_t))
+#define BLOCK_U64S (HMAC_SHA256_BLOCKSIZE / sizeof(uint64_t))
 
 static inline void xor_block(uint64_t block[BLOCK_U64S], uint64_t pad)
 {
@@ -15,17 +15,15 @@ static inline void xor_block(uint64_t block[BLOCK_U64S], uint64_t pad)
                block[i] ^= pad;
 }
 
-#if 1
-void hmac_sha256(struct hmac_sha256 *hmac,
-                const void *k, size_t ksize,
-                const void *d, size_t dsize)
+void hmac_sha256_init(struct hmac_sha256_ctx *ctx,
+                     const void *k, size_t ksize)
 {
-       struct sha256_ctx shactx;
-       uint64_t block[BLOCK_U64S];
-       struct sha256 hash, hashed_key;
+       struct sha256 hashed_key;
+       /* We use k_opad as k_ipad temporarily. */
+       uint64_t *k_ipad = ctx->k_opad;
 
        /* (keys longer than B bytes are first hashed using H) */
-       if (ksize > sizeof(block)) {
+       if (ksize > HMAC_SHA256_BLOCKSIZE) {
                sha256(&hashed_key, k, ksize);
                k = &hashed_key;
                ksize = sizeof(hashed_key);
@@ -37,30 +35,48 @@ void hmac_sha256(struct hmac_sha256 *hmac,
         *  (e.g., if K is of length 20 bytes and B=64, then K will be
         *   appended with 44 zero bytes 0x00)
         */
-       memcpy(block, k, ksize);
-       memset((char *)block + ksize, 0, sizeof(block) - ksize);
+       memcpy(k_ipad, k, ksize);
+       memset((char *)k_ipad + ksize, 0, HMAC_SHA256_BLOCKSIZE - ksize);
 
        /*
         * (2) XOR (bitwise exclusive-OR) the B byte string computed
         * in step (1) with ipad
         */
-       xor_block(block, IPAD);
+       xor_block(k_ipad, IPAD);
 
        /*
+        * We start (4) here, appending text later:
+        *
         * (3) append the stream of data 'text' to the B byte string resulting
         * from step (2)
         * (4) apply H to the stream generated in step (3)
         */
-       sha256_init(&shactx);
-       sha256_update(&shactx, block, sizeof(block));
-       sha256_update(&shactx, d, dsize);
-       sha256_done(&shactx, &hash);
+       sha256_init(&ctx->sha);
+       sha256_update(&ctx->sha, k_ipad, HMAC_SHA256_BLOCKSIZE);
 
        /*
         * (5) XOR (bitwise exclusive-OR) the B byte string computed in
         * step (1) with opad
         */
-       xor_block(block, IPAD^OPAD);
+       xor_block(ctx->k_opad, IPAD^OPAD);
+}
+
+void hmac_sha256_update(struct hmac_sha256_ctx *ctx, const void *p, size_t size)
+{
+       /* This is the appending-text part of this:
+        *
+        * (3) append the stream of data 'text' to the B byte string resulting
+        * from step (2)
+        * (4) apply H to the stream generated in step (3)
+        */
+       sha256_update(&ctx->sha, p, size);
+}
+
+void hmac_sha256_done(struct hmac_sha256_ctx *ctx,
+                     struct hmac_sha256 *hmac)
+{
+       /* (4) apply H to the stream generated in step (3) */
+       sha256_done(&ctx->sha, &hmac->sha);
 
        /*
         * (6) append the H result from step (4) to the B byte string
@@ -68,10 +84,22 @@ void hmac_sha256(struct hmac_sha256 *hmac,
         * (7) apply H to the stream generated in step (6) and output
         * the result
         */
-       sha256_init(&shactx);
-       sha256_update(&shactx, block, sizeof(block));
-       sha256_update(&shactx, &hash, sizeof(hash));
-       sha256_done(&shactx, &hmac->sha);
+       sha256_init(&ctx->sha);
+       sha256_update(&ctx->sha, ctx->k_opad, sizeof(ctx->k_opad));
+       sha256_update(&ctx->sha, &hmac->sha, sizeof(hmac->sha));
+       sha256_done(&ctx->sha, &hmac->sha);
+}
+
+#if 1
+void hmac_sha256(struct hmac_sha256 *hmac,
+                const void *k, size_t ksize,
+                const void *d, size_t dsize)
+{
+       struct hmac_sha256_ctx ctx;
+
+       hmac_sha256_init(&ctx, k, ksize);
+       hmac_sha256_update(&ctx, d, dsize);
+       hmac_sha256_done(&ctx, hmac);
 }
 #else
 /* Direct mapping from MD5 example in RFC2104 */