siphash: A keyed hash designed by Aumasson and djb

[ccan] / ccan / siphash / _info

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+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * siphash - a keyed hash function
+ *
+ * SipHash-c-d, where `c` is the number of rounds per message chunk
+ *              and `d` the number of finalization rounds,
+ * "is a family of pseudorandom functions optimized for speed on short
+ * messages"
+ *
+ * Implemented from the paper https://131002.net/siphash/
+ * The designers recommend using SipHash-2-4 or SipHash-4-8
+ *
+ * SipHash-c-d uses a 16-byte key.
+ * To defend against hash-flooding, the application needs to use
+ * a new random key regularly.
+ *
+ * The designers of SipHash claim it is cryptographically strong
+ * to use as MAC with secret key but _not_collision_resistant_.
+ *
+ * Returns one 64-bit word as the hash function result.
+ *
+ * Example:
+ *     // Outputs "cf2794e0277187b7"
+ *     #include <stdio.h>
+ *     #include <ccan/siphash/siphash.h>
+ *
+ *     int main(void)
+ *     {
+ *             unsigned char t_key[16] =
+ *                     {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
+ *             unsigned char data[4] = "\0\1\2\3";
+ *             uint64_t hash = siphash_2_4(data, sizeof(data), t_key);
+ *             printf("%llx\n", (unsigned long long)hash);
+ *
+ *             return 0;
+ *     }
+ *
+ *
+ * License: GPL (v2 or any later version)
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0) {
+               printf("ccan/endian\n");
+               return 0;
+       }
+
+       return 1;
+}