Move poly1305_get_tag() into poly1305.c, hide poly1305_init().

[tinc] / src / chacha-poly1305 / poly1305.c

diff --git a/src/chacha-poly1305/poly1305.c b/src/chacha-poly1305/poly1305.c
index 0c90564..b25435a 100644 (file)
--- a/src/chacha-poly1305/poly1305.c
+++ b/src/chacha-poly1305/poly1305.c
@@ -5,6 +5,20 @@ public domain
 
 #include "poly1305.h"
 
+/* use memcpy() to copy blocks of memory (typically faster) */
+#define USE_MEMCPY          1
+/* use unaligned little-endian load/store (can be faster) */
+#define USE_UNALIGNED       0
+
+struct poly1305_context {
+       uint32_t r[5];
+       uint32_t h[5];
+       uint32_t pad[4];
+       size_t leftover;
+       unsigned char buffer[POLY1305_BLOCK_SIZE];
+       unsigned char final;
+};
+
 #if (USE_UNALIGNED == 1)
 #define U8TO32(p) \
        (*((uint32_t *)(p)))
@@ -33,7 +47,7 @@ U32TO8(unsigned char *p, uint32_t v) {
 }
 #endif
 
-void
+static void
 poly1305_init(struct poly1305_context *st, const unsigned char key[32]) {
        /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
        st->r[0] = (U8TO32(&key[ 0])) & 0x3ffffff;
@@ -131,7 +145,7 @@ poly1305_blocks(struct poly1305_context *st, const unsigned char *m, size_t byte
        st->h[4] = h4;
 }
 
-void
+static void
 poly1305_finish(struct poly1305_context *st, unsigned char mac[16]) {
        uint32_t h0, h1, h2, h3, h4, c;
        uint32_t g0, g1, g2, g3, g4;
@@ -241,8 +255,7 @@ poly1305_finish(struct poly1305_context *st, unsigned char mac[16]) {
        st->pad[3] = 0;
 }
 
-
-void
+static void
 poly1305_update(struct poly1305_context *st, const unsigned char *m, size_t bytes) {
        size_t i;
 
@@ -293,10 +306,37 @@ poly1305_update(struct poly1305_context *st, const unsigned char *m, size_t byte
        }
 }
 
+/**
+ * Poly1305 tag generation. This concatenates a string according to the rules
+ * outlined in RFC 7539 and calculates the tag.
+ *
+ * \param key 32 byte secret one-time key for poly1305
+ * \param ct ciphertext
+ * \param ct_len ciphertext length in bytes
+ * \param tag pointer to 16 bytes for tag storage
+ */
 void
-poly1305_auth(unsigned char mac[16], const unsigned char *m, size_t bytes, const unsigned char key[32]) {
+poly1305_get_tag(const unsigned char key[32], const void *ct, int ct_len, unsigned char tag[16]) {
        struct poly1305_context ctx;
+       unsigned left_over;
+       uint64_t len;
+       unsigned char pad[16];
+
        poly1305_init(&ctx, key);
-       poly1305_update(&ctx, m, bytes);
-       poly1305_finish(&ctx, mac);
+       memset(&pad, 0, sizeof(pad));
+
+       /* payload and padding */
+       poly1305_update(&ctx, ct, ct_len);
+       left_over = ct_len % 16;
+
+       if(left_over) {
+               poly1305_update(&ctx, pad, 16 - left_over);
+       }
+
+       /* lengths */
+       len = 0;
+       poly1305_update(&ctx, (unsigned char *)&len, 8);
+       len = ct_len;
+       poly1305_update(&ctx, (unsigned char *)&len, 8);
+       poly1305_finish(&ctx, tag);
 }