Import Poly1305 Message Authentication Code

Poly1305 is a one-time authenticator designed by Daniel J. Bernstein.
This is a slightly adjusted public domain implementation by Andrew Moon
found at https://github.com/floodyberry/poly1305-donna

ok jsing, previous version ok djm, looked at by reyk@

2 files changed, 326 insertions, 0 deletions

diff --git a/sys/crypto/poly1305.c b/sys/crypto/poly1305.c
new file mode 100644
index 00000000000..93ab9ef7359
--- /dev/null
+++ b/sys/crypto/poly1305.c
@@ -0,0 +1,300 @@
+/*
+ * Public Domain poly1305 from Andrew Moon
+ * Based on poly1305-donna.c, poly1305-donna-32.h and poly1305-donna.h from:
+ *   https://github.com/floodyberry/poly1305-donna
+ */
+
+#include <sys/types.h>
+#include <sys/systm.h>
+
+#include "poly1305.h"
+
+/*
+ * poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication
+ * and 64 bit addition.
+ */
+
+/* interpret four 8 bit unsigned integers as a 32 bit unsigned integer in little endian */
+static unsigned long
+U8TO32(const unsigned char *p)
+{
+	return (((unsigned long)(p[0] & 0xff)) |
+	    ((unsigned long)(p[1] & 0xff) <<  8) |
+	    ((unsigned long)(p[2] & 0xff) << 16) |
+	    ((unsigned long)(p[3] & 0xff) << 24));
+}
+
+/* store a 32 bit unsigned integer as four 8 bit unsigned integers in little endian */
+static void
+U32TO8(unsigned char *p, unsigned long v)
+{
+	p[0] = (v) & 0xff;
+	p[1] = (v >>  8) & 0xff;
+	p[2] = (v >> 16) & 0xff;
+	p[3] = (v >> 24) & 0xff;
+}
+
+void
+poly1305_init(poly1305_state *st, const unsigned char key[32])
+{
+	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
+	st->r[0] = (U8TO32(&key[0])) & 0x3ffffff;
+	st->r[1] = (U8TO32(&key[3]) >> 2) & 0x3ffff03;
+	st->r[2] = (U8TO32(&key[6]) >> 4) & 0x3ffc0ff;
+	st->r[3] = (U8TO32(&key[9]) >> 6) & 0x3f03fff;
+	st->r[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff;
+
+	/* h = 0 */
+	st->h[0] = 0;
+	st->h[1] = 0;
+	st->h[2] = 0;
+	st->h[3] = 0;
+	st->h[4] = 0;
+
+	/* save pad for later */
+	st->pad[0] = U8TO32(&key[16]);
+	st->pad[1] = U8TO32(&key[20]);
+	st->pad[2] = U8TO32(&key[24]);
+	st->pad[3] = U8TO32(&key[28]);
+
+	st->leftover = 0;
+	st->final = 0;
+}
+
+static void
+poly1305_blocks(poly1305_state *st, const unsigned char *m, size_t bytes)
+{
+	const unsigned long hibit = (st->final) ? 0 : (1 << 24); /* 1 << 128 */
+	unsigned long r0, r1, r2, r3, r4;
+	unsigned long s1, s2, s3, s4;
+	unsigned long h0, h1, h2, h3, h4;
+	unsigned long long d0, d1, d2, d3, d4;
+	unsigned long c;
+
+	r0 = st->r[0];
+	r1 = st->r[1];
+	r2 = st->r[2];
+	r3 = st->r[3];
+	r4 = st->r[4];
+
+	s1 = r1 * 5;
+	s2 = r2 * 5;
+	s3 = r3 * 5;
+	s4 = r4 * 5;
+
+	h0 = st->h[0];
+	h1 = st->h[1];
+	h2 = st->h[2];
+	h3 = st->h[3];
+	h4 = st->h[4];
+
+	while (bytes >= poly1305_block_size) {
+		/* h += m[i] */
+		h0 += (U8TO32(m + 0)) & 0x3ffffff;
+		h1 += (U8TO32(m + 3) >> 2) & 0x3ffffff;
+		h2 += (U8TO32(m + 6) >> 4) & 0x3ffffff;
+		h3 += (U8TO32(m + 9) >> 6) & 0x3ffffff;
+		h4 += (U8TO32(m + 12) >> 8) | hibit;
+
+		/* h *= r */
+		d0 = ((unsigned long long)h0 * r0) +
+		    ((unsigned long long)h1 * s4) +
+		    ((unsigned long long)h2 * s3) +
+		    ((unsigned long long)h3 * s2) +
+		    ((unsigned long long)h4 * s1);
+		d1 = ((unsigned long long)h0 * r1) +
+		    ((unsigned long long)h1 * r0) +
+		    ((unsigned long long)h2 * s4) +
+		    ((unsigned long long)h3 * s3) +
+		    ((unsigned long long)h4 * s2);
+		d2 = ((unsigned long long)h0 * r2) +
+		    ((unsigned long long)h1 * r1) +
+		    ((unsigned long long)h2 * r0) +
+		    ((unsigned long long)h3 * s4) +
+		    ((unsigned long long)h4 * s3);
+		d3 = ((unsigned long long)h0 * r3) +
+		    ((unsigned long long)h1 * r2) +
+		    ((unsigned long long)h2 * r1) +
+		    ((unsigned long long)h3 * r0) +
+		    ((unsigned long long)h4 * s4);
+		d4 = ((unsigned long long)h0 * r4) +
+		    ((unsigned long long)h1 * r3) +
+		    ((unsigned long long)h2 * r2) +
+		    ((unsigned long long)h3 * r1) +
+		    ((unsigned long long)h4 * r0);
+
+		/* (partial) h %= p */
+		c = (unsigned long)(d0 >> 26);
+		h0 = (unsigned long)d0 & 0x3ffffff;
+		d1 += c;
+		c = (unsigned long)(d1 >> 26);
+		h1 = (unsigned long)d1 & 0x3ffffff;
+		d2 += c;
+		c = (unsigned long)(d2 >> 26);
+		h2 = (unsigned long)d2 & 0x3ffffff;
+		d3 += c;
+		c = (unsigned long)(d3 >> 26);
+		h3 = (unsigned long)d3 & 0x3ffffff;
+		d4 += c;
+		c = (unsigned long)(d4 >> 26);
+		h4 = (unsigned long)d4 & 0x3ffffff;
+		h0 += c * 5;
+		c = (h0 >> 26);
+		h0 = h0 & 0x3ffffff;
+		h1 += c;
+
+		m += poly1305_block_size;
+		bytes -= poly1305_block_size;
+	}
+
+	st->h[0] = h0;
+	st->h[1] = h1;
+	st->h[2] = h2;
+	st->h[3] = h3;
+	st->h[4] = h4;
+}
+
+void
+poly1305_update(poly1305_state *st, const unsigned char *m, size_t bytes)
+{
+	size_t i;
+
+	/* handle leftover */
+	if (st->leftover) {
+		size_t want = (poly1305_block_size - st->leftover);
+		if (want > bytes)
+			want = bytes;
+		for (i = 0; i < want; i++)
+			st->buffer[st->leftover + i] = m[i];
+		bytes -= want;
+		m += want;
+		st->leftover += want;
+		if (st->leftover < poly1305_block_size)
+			return;
+		poly1305_blocks(st, st->buffer, poly1305_block_size);
+		st->leftover = 0;
+	}
+
+	/* process full blocks */
+	if (bytes >= poly1305_block_size) {
+		size_t want = (bytes & ~(poly1305_block_size - 1));
+		poly1305_blocks(st, m, want);
+		m += want;
+		bytes -= want;
+	}
+
+	/* store leftover */
+	if (bytes) {
+		for (i = 0; i < bytes; i++)
+			st->buffer[st->leftover + i] = m[i];
+		st->leftover += bytes;
+	}
+}
+
+void
+poly1305_finish(poly1305_state *st, unsigned char mac[16])
+{
+	unsigned long h0, h1, h2, h3, h4, c;
+	unsigned long g0, g1, g2, g3, g4;
+	unsigned long long f;
+	unsigned long mask;
+
+	/* process the remaining block */
+	if (st->leftover) {
+		size_t i = st->leftover;
+		st->buffer[i++] = 1;
+		for (; i < poly1305_block_size; i++)
+			st->buffer[i] = 0;
+		st->final = 1;
+		poly1305_blocks(st, st->buffer, poly1305_block_size);
+	}
+
+	/* fully carry h */
+	h0 = st->h[0];
+	h1 = st->h[1];
+	h2 = st->h[2];
+	h3 = st->h[3];
+	h4 = st->h[4];
+
+	c = h1 >> 26;
+	h1 = h1 & 0x3ffffff;
+	h2 += c;
+	c = h2 >> 26;
+	h2 = h2 & 0x3ffffff;
+	h3 += c;
+	c = h3 >> 26;
+	h3 = h3 & 0x3ffffff;
+	h4 += c;
+	c = h4 >> 26;
+	h4 = h4 & 0x3ffffff;
+	h0 += c * 5;
+	c = h0 >> 26;
+	h0 = h0 & 0x3ffffff;
+	h1 += c;
+
+	/* compute h + -p */
+	g0 = h0 + 5;
+	c = g0 >> 26;
+	g0 &= 0x3ffffff;
+	g1 = h1 + c;
+	c = g1 >> 26;
+	g1 &= 0x3ffffff;
+	g2 = h2 + c;
+	c = g2 >> 26;
+	g2 &= 0x3ffffff;
+	g3 = h3 + c;
+	c = g3 >> 26;
+	g3 &= 0x3ffffff;
+	g4 = h4 + c - (1 << 26);
+
+	/* select h if h < p, or h + -p if h >= p */
+	mask = (g4 >> ((sizeof(unsigned long) * 8) - 1)) - 1;
+	g0 &= mask;
+	g1 &= mask;
+	g2 &= mask;
+	g3 &= mask;
+	g4 &= mask;
+	mask = ~mask;
+	h0 = (h0 & mask) | g0;
+	h1 = (h1 & mask) | g1;
+	h2 = (h2 & mask) | g2;
+	h3 = (h3 & mask) | g3;
+	h4 = (h4 & mask) | g4;
+
+	/* h = h % (2^128) */
+	h0 = ((h0) | (h1 << 26)) & 0xffffffff;
+	h1 = ((h1 >>  6) | (h2 << 20)) & 0xffffffff;
+	h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
+	h3 = ((h3 >> 18) | (h4 <<  8)) & 0xffffffff;
+
+	/* mac = (h + pad) % (2^128) */
+	f = (unsigned long long)h0 + st->pad[0];
+	h0 = (unsigned long)f;
+	f = (unsigned long long)h1 + st->pad[1] + (f >> 32);
+	h1 = (unsigned long)f;
+	f = (unsigned long long)h2 + st->pad[2] + (f >> 32);
+	h2 = (unsigned long)f;
+	f = (unsigned long long)h3 + st->pad[3] + (f >> 32);
+	h3 = (unsigned long)f;
+
+	U32TO8(mac +  0, h0);
+	U32TO8(mac +  4, h1);
+	U32TO8(mac +  8, h2);
+	U32TO8(mac + 12, h3);
+
+	/* zero out the state */
+	st->h[0] = 0;
+	st->h[1] = 0;
+	st->h[2] = 0;
+	st->h[3] = 0;
+	st->h[4] = 0;
+	st->r[0] = 0;
+	st->r[1] = 0;
+	st->r[2] = 0;
+	st->r[3] = 0;
+	st->r[4] = 0;
+	st->pad[0] = 0;
+	st->pad[1] = 0;
+	st->pad[2] = 0;
+	st->pad[3] = 0;
+}
diff --git a/sys/crypto/poly1305.h b/sys/crypto/poly1305.h
new file mode 100644
index 00000000000..a36b84a6ad9
--- /dev/null
+++ b/sys/crypto/poly1305.h
@@ -0,0 +1,26 @@
+/*
+ * Public Domain poly1305 from Andrew Moon
+ *
+ * poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication
+ * and 64 bit addition from https://github.com/floodyberry/poly1305-donna
+ */
+
+#ifndef _POLY1305_H_
+#define _POLY1305_H_
+
+#define poly1305_block_size 16
+
+typedef struct poly1305_state {
+	unsigned long r[5];
+	unsigned long h[5];
+	unsigned long pad[4];
+	size_t leftover;
+	unsigned char buffer[poly1305_block_size];
+	unsigned char final;
+} poly1305_state;
+
+void	poly1305_init(poly1305_state *, const unsigned char[32]);
+void	poly1305_update(poly1305_state *, const unsigned char *, size_t);
+void	poly1305_finish(poly1305_state *, unsigned char[16]);
+
+#endif	/* _POLY1305_H_ */