Add Poly1305 implementation

2 files changed, 158 insertions, 0 deletions

diff --git a/src/crypto/poly1305.cpp b/src/crypto/poly1305.cpp
new file mode 100644
index 0000000000..8a86c9601c
--- /dev/null
+++ b/src/crypto/poly1305.cpp
@@ -0,0 +1,141 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+// Based on the public domain implementation by Andrew Moon
+// poly1305-donna-unrolled.c from https://github.com/floodyberry/poly1305-donna
+
+#include <crypto/common.h>
+#include <crypto/poly1305.h>
+
+#include <string.h>
+
+#define mul32x32_64(a,b) ((uint64_t)(a) * (b))
+
+void poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
+    uint32_t t0,t1,t2,t3;
+    uint32_t h0,h1,h2,h3,h4;
+    uint32_t r0,r1,r2,r3,r4;
+    uint32_t s1,s2,s3,s4;
+    uint32_t b, nb;
+    size_t j;
+    uint64_t t[5];
+    uint64_t f0,f1,f2,f3;
+    uint64_t g0,g1,g2,g3,g4;
+    uint64_t c;
+    unsigned char mp[16];
+
+    /* clamp key */
+    t0 = ReadLE32(key+0);
+    t1 = ReadLE32(key+4);
+    t2 = ReadLE32(key+8);
+    t3 = ReadLE32(key+12);
+
+    /* precompute multipliers */
+    r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
+    r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
+    r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
+    r3 = t2 & 0x3f03fff; t3 >>= 8;
+    r4 = t3 & 0x00fffff;
+
+    s1 = r1 * 5;
+    s2 = r2 * 5;
+    s3 = r3 * 5;
+    s4 = r4 * 5;
+
+    /* init state */
+    h0 = 0;
+    h1 = 0;
+    h2 = 0;
+    h3 = 0;
+    h4 = 0;
+
+    /* full blocks */
+    if (inlen < 16) goto poly1305_donna_atmost15bytes;
+poly1305_donna_16bytes:
+    m += 16;
+    inlen -= 16;
+
+    t0 = ReadLE32(m-16);
+    t1 = ReadLE32(m-12);
+    t2 = ReadLE32(m-8);
+    t3 = ReadLE32(m-4);
+
+    h0 += t0 & 0x3ffffff;
+    h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
+    h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
+    h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
+    h4 += (t3 >> 8) | (1 << 24);
+
+
+poly1305_donna_mul:
+    t[0]  = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
+    t[1]  = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
+    t[2]  = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
+    t[3]  = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
+    t[4]  = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
+
+                    h0 = (uint32_t)t[0] & 0x3ffffff; c =           (t[0] >> 26);
+    t[1] += c;      h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
+    t[2] += b;      h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
+    t[3] += b;      h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
+    t[4] += b;      h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
+    h0 += b * 5;
+
+    if (inlen >= 16) goto poly1305_donna_16bytes;
+
+    /* final bytes */
+poly1305_donna_atmost15bytes:
+    if (!inlen) goto poly1305_donna_finish;
+
+    for (j = 0; j < inlen; j++) mp[j] = m[j];
+    mp[j++] = 1;
+    for (; j < 16; j++) mp[j] = 0;
+    inlen = 0;
+
+    t0 = ReadLE32(mp+0);
+    t1 = ReadLE32(mp+4);
+    t2 = ReadLE32(mp+8);
+    t3 = ReadLE32(mp+12);
+
+    h0 += t0 & 0x3ffffff;
+    h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
+    h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
+    h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
+    h4 += (t3 >> 8);
+
+    goto poly1305_donna_mul;
+
+poly1305_donna_finish:
+                 b = h0 >> 26; h0 = h0 & 0x3ffffff;
+    h1 +=     b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
+    h2 +=     b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
+    h3 +=     b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
+    h4 +=     b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
+    h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
+    h1 +=     b;
+
+    g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
+    g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
+    g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
+    g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
+    g4 = h4 + b - (1 << 26);
+
+    b = (g4 >> 31) - 1;
+    nb = ~b;
+    h0 = (h0 & nb) | (g0 & b);
+    h1 = (h1 & nb) | (g1 & b);
+    h2 = (h2 & nb) | (g2 & b);
+    h3 = (h3 & nb) | (g3 & b);
+    h4 = (h4 & nb) | (g4 & b);
+
+    f0 = ((h0      ) | (h1 << 26)) + (uint64_t)ReadLE32(&key[16]);
+    f1 = ((h1 >>  6) | (h2 << 20)) + (uint64_t)ReadLE32(&key[20]);
+    f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)ReadLE32(&key[24]);
+    f3 = ((h3 >> 18) | (h4 <<  8)) + (uint64_t)ReadLE32(&key[28]);
+
+    WriteLE32(&out[ 0], f0); f1 += (f0 >> 32);
+    WriteLE32(&out[ 4], f1); f2 += (f1 >> 32);
+    WriteLE32(&out[ 8], f2); f3 += (f2 >> 32);
+    WriteLE32(&out[12], f3);
+}
diff --git a/src/crypto/poly1305.h b/src/crypto/poly1305.h
new file mode 100644
index 0000000000..1598b013b9
--- /dev/null
+++ b/src/crypto/poly1305.h
@@ -0,0 +1,17 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_CRYPTO_POLY1305_H
+#define BITCOIN_CRYPTO_POLY1305_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#define POLY1305_KEYLEN 32
+#define POLY1305_TAGLEN 16
+
+void poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen,
+    const unsigned char key[POLY1305_KEYLEN]);
+
+#endif // BITCOIN_CRYPTO_POLY1305_H