Add sha512sum(1)

sha512.h

@@ -0,0 +1,18 @@
+/* public domain sha512 implementation based on fips180-3 */
+
+struct sha512 {
+	uint64_t len;     /* processed message length */
+	uint64_t h[8];    /* hash state */
+	uint8_t buf[128]; /* message block buffer */
+};
+
+enum { SHA512_DIGEST_LENGTH = 64 };
+
+/* reset state */
+void sha512_init(void *ctx);
+/* process message */
+void sha512_update(void *ctx, const void *m, unsigned long len);
+/* get message digest */
+/* state is ruined after sum, keep a copy if multiple sum is needed */
+/* part of the message might be left in s, zero it if secrecy is needed */
+void sha512_sum(void *ctx, uint8_t md[SHA512_DIGEST_LENGTH]);