Expose an incremental API in addition to the one-shot routines.

The digest routines use init/update/sum, where sum will automatically
copy the internal state to support calculating running digests.

The XOF routines use init/absorb/squeeze, which behave exactly as stated
on the tin.

1 files changed, 47 insertions, 0 deletions

diff --git a/src/ext/keccak-tiny/keccak-tiny.h b/src/ext/keccak-tiny/keccak-tiny.h
index c4c678e874..04044cdc64 100644
--- a/src/ext/keccak-tiny/keccak-tiny.h
+++ b/src/ext/keccak-tiny/keccak-tiny.h
@@ -4,6 +4,53 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define KECCAK_MAX_RATE 200
+
+/* Calculate the rate (block size) from the security target. */
+#define KECCAK_RATE(bits) (KECCAK_MAX_RATE - (bits / 4))
+
+/* The internal structure of a FIPS202 hash/xof instance.  Most callers
+ * should treat this as an opaque structure.
+ */
+typedef struct keccak_state {
+  uint8_t a[KECCAK_MAX_RATE];
+  size_t rate;
+  uint8_t delim;
+
+  uint8_t block[KECCAK_MAX_RATE];
+  size_t offset;
+
+  uint8_t finalized : 1;
+} keccak_state;
+
+/* Initialize a Keccak instance suitable for SHA-3 hash functions. */
+int keccak_digest_init(keccak_state *s, size_t bits);
+
+/* Feed more data into the SHA-3 hash instance. */
+int keccak_digest_update(keccak_state *s, const uint8_t *buf, size_t len);
+
+/* Calculate the SHA-3 hash digest.  The state is unmodified to support
+ * calculating multiple/rolling digests.
+ */
+int keccak_digest_sum(const keccak_state *s, uint8_t *out, size_t outlen);
+
+/* Initialize a Keccak instance suitable for XOFs (SHAKE-128/256). */
+int keccak_xof_init(keccak_state *s, size_t bits);
+
+/* Absorb more data into the XOF.  Must not be called after a squeeze call. */
+int keccak_xof_absorb(keccak_state *s, const uint8_t *buf, size_t len);
+
+/* Squeeze data out of the XOF. Must not attempt to absorb additional data,
+ * after a squeeze has been called.
+ */
+int keccak_xof_squeeze(keccak_state *s, uint8_t *out, size_t outlen);
+
+/* Clone an existing hash/XOF instance. */
+void keccak_clone(keccak_state *out, const keccak_state *in);
+
+/* Cleanse sensitive data from a given hash instance. */
+void keccak_cleanse(keccak_state *s);
+
 #define decshake(bits) \
   int shake##bits(uint8_t*, size_t, const uint8_t*, size_t);