Add ChaCha20

4 files changed, 253 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 8a32156884..89dd4c8f77 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -242,6 +242,8 @@ crypto_libbitcoin_crypto_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_a_SOURCES = \
   crypto/aes.cpp \
   crypto/aes.h \
+  crypto/chacha20.h \
+  crypto/chacha20.cpp \
   crypto/common.h \
   crypto/hmac_sha256.cpp \
   crypto/hmac_sha256.h \
diff --git a/src/crypto/chacha20.cpp b/src/crypto/chacha20.cpp
new file mode 100644
index 0000000000..816ae870e1
--- /dev/null
+++ b/src/crypto/chacha20.cpp
@@ -0,0 +1,180 @@
+// Copyright (c) 2017 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 'merged' by D. J. Bernstein
+// See https://cr.yp.to/chacha.html.
+
+#include "crypto/common.h"
+#include "crypto/chacha20.h"
+
+#include <string.h>
+
+constexpr static inline uint32_t rotl32(uint32_t v, int c) { return (v << c) | (v >> (32 - c)); }
+
+#define QUARTERROUND(a,b,c,d) \
+  a += b; d = rotl32(d ^ a, 16); \
+  c += d; b = rotl32(b ^ c, 12); \
+  a += b; d = rotl32(d ^ a, 8); \
+  c += d; b = rotl32(b ^ c, 7);
+
+static const unsigned char sigma[] = "expand 32-byte k";
+static const unsigned char tau[] = "expand 16-byte k";
+
+void ChaCha20::SetKey(const unsigned char* k, size_t keylen)
+{
+    const unsigned char *constants;
+
+    input[4] = ReadLE32(k + 0);
+    input[5] = ReadLE32(k + 4);
+    input[6] = ReadLE32(k + 8);
+    input[7] = ReadLE32(k + 12);
+    if (keylen == 32) { /* recommended */
+        k += 16;
+        constants = sigma;
+    } else { /* keylen == 16 */
+        constants = tau;
+    }
+    input[8] = ReadLE32(k + 0);
+    input[9] = ReadLE32(k + 4);
+    input[10] = ReadLE32(k + 8);
+    input[11] = ReadLE32(k + 12);
+    input[0] = ReadLE32(constants + 0);
+    input[1] = ReadLE32(constants + 4);
+    input[2] = ReadLE32(constants + 8);
+    input[3] = ReadLE32(constants + 12);
+    input[12] = 0;
+    input[13] = 0;
+    input[14] = 0;
+    input[15] = 0;
+}
+
+ChaCha20::ChaCha20()
+{
+    memset(input, 0, sizeof(input));
+}
+
+ChaCha20::ChaCha20(const unsigned char* k, size_t keylen)
+{
+    SetKey(k, keylen);
+}
+
+void ChaCha20::SetIV(uint64_t iv)
+{
+    input[14] = iv;
+    input[15] = iv >> 32;
+}
+
+void ChaCha20::Seek(uint64_t pos)
+{
+    input[12] = pos;
+    input[13] = pos >> 32;
+}
+
+void ChaCha20::Output(unsigned char* c, size_t bytes)
+{
+    uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
+    uint32_t j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
+    unsigned char *ctarget = NULL;
+    unsigned char tmp[64];
+    unsigned int i;
+
+    if (!bytes) return;
+
+    j0 = input[0];
+    j1 = input[1];
+    j2 = input[2];
+    j3 = input[3];
+    j4 = input[4];
+    j5 = input[5];
+    j6 = input[6];
+    j7 = input[7];
+    j8 = input[8];
+    j9 = input[9];
+    j10 = input[10];
+    j11 = input[11];
+    j12 = input[12];
+    j13 = input[13];
+    j14 = input[14];
+    j15 = input[15];
+
+    for (;;) {
+        if (bytes < 64) {
+            ctarget = c;
+            c = tmp;
+        }
+        x0 = j0;
+        x1 = j1;
+        x2 = j2;
+        x3 = j3;
+        x4 = j4;
+        x5 = j5;
+        x6 = j6;
+        x7 = j7;
+        x8 = j8;
+        x9 = j9;
+        x10 = j10;
+        x11 = j11;
+        x12 = j12;
+        x13 = j13;
+        x14 = j14;
+        x15 = j15;
+        for (i = 20;i > 0;i -= 2) {
+            QUARTERROUND( x0, x4, x8,x12)
+            QUARTERROUND( x1, x5, x9,x13)
+            QUARTERROUND( x2, x6,x10,x14)
+            QUARTERROUND( x3, x7,x11,x15)
+            QUARTERROUND( x0, x5,x10,x15)
+            QUARTERROUND( x1, x6,x11,x12)
+            QUARTERROUND( x2, x7, x8,x13)
+            QUARTERROUND( x3, x4, x9,x14)
+        }
+        x0 += j0;
+        x1 += j1;
+        x2 += j2;
+        x3 += j3;
+        x4 += j4;
+        x5 += j5;
+        x6 += j6;
+        x7 += j7;
+        x8 += j8;
+        x9 += j9;
+        x10 += j10;
+        x11 += j11;
+        x12 += j12;
+        x13 += j13;
+        x14 += j14;
+        x15 += j15;
+
+        ++j12;
+        if (!j12) ++j13;
+
+        WriteLE32(c + 0, x0);
+        WriteLE32(c + 4, x1);
+        WriteLE32(c + 8, x2);
+        WriteLE32(c + 12, x3);
+        WriteLE32(c + 16, x4);
+        WriteLE32(c + 20, x5);
+        WriteLE32(c + 24, x6);
+        WriteLE32(c + 28, x7);
+        WriteLE32(c + 32, x8);
+        WriteLE32(c + 36, x9);
+        WriteLE32(c + 40, x10);
+        WriteLE32(c + 44, x11);
+        WriteLE32(c + 48, x12);
+        WriteLE32(c + 52, x13);
+        WriteLE32(c + 56, x14);
+        WriteLE32(c + 60, x15);
+
+        if (bytes <= 64) {
+            if (bytes < 64) {
+                for (i = 0;i < bytes;++i) ctarget[i] = c[i];
+            }
+            input[12] = j12;
+            input[13] = j13;
+            return;
+        }
+        bytes -= 64;
+        c += 64;
+    }
+}
diff --git a/src/crypto/chacha20.h b/src/crypto/chacha20.h
new file mode 100644
index 0000000000..a305977bcd
--- /dev/null
+++ b/src/crypto/chacha20.h
@@ -0,0 +1,26 @@
+// Copyright (c) 2017 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_CHACHA20_H
+#define BITCOIN_CRYPTO_CHACHA20_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+/** A PRNG class for ChaCha20. */
+class ChaCha20
+{
+private:
+    uint32_t input[16];
+
+public:
+    ChaCha20();
+    ChaCha20(const unsigned char* key, size_t keylen);
+    void SetKey(const unsigned char* key, size_t keylen);
+    void SetIV(uint64_t iv);
+    void Seek(uint64_t pos);
+    void Output(unsigned char* output, size_t bytes);
+};
+
+#endif // BITCOIN_CRYPTO_CHACHA20_H
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index 4d17417179..a20182afb8 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "crypto/aes.h"
+#include "crypto/chacha20.h"
 #include "crypto/ripemd160.h"
 #include "crypto/sha1.h"
 #include "crypto/sha256.h"
@@ -187,6 +188,19 @@ void TestAES256CBC(const std::string &hexkey, const std::string &hexiv, bool pad
     }
 }
 
+void TestChaCha20(const std::string &hexkey, uint64_t nonce, uint64_t seek, const std::string& hexout)
+{
+    std::vector<unsigned char> key = ParseHex(hexkey);
+    ChaCha20 rng(key.data(), key.size());
+    rng.SetIV(nonce);
+    rng.Seek(seek);
+    std::vector<unsigned char> out = ParseHex(hexout);
+    std::vector<unsigned char> outres;
+    outres.resize(out.size());
+    rng.Output(outres.data(), outres.size());
+    BOOST_CHECK(out == outres);
+}
+
 std::string LongTestString(void) {
     std::string ret;
     for (int i=0; i<200000; i++) {
@@ -439,4 +453,35 @@ BOOST_AUTO_TEST_CASE(aes_cbc_testvectors) {
                   "b2eb05e2c39be9fcda6c19078c6a9d1b3f461796d6b0d6b2e0c2a72b4d80e644");
 }
 
+
+BOOST_AUTO_TEST_CASE(chacha20_testvector)
+{
+    // Test vector from RFC 7539
+    TestChaCha20("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f", 0x4a000000UL, 1,
+                 "224f51f3401bd9e12fde276fb8631ded8c131f823d2c06e27e4fcaec9ef3cf788a3b0aa372600a92b57974cded2b9334794cb"
+                 "a40c63e34cdea212c4cf07d41b769a6749f3f630f4122cafe28ec4dc47e26d4346d70b98c73f3e9c53ac40c5945398b6eda1a"
+                 "832c89c167eacd901d7e2bf363");
+
+    // Test vectors from https://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-04#section-7
+    TestChaCha20("0000000000000000000000000000000000000000000000000000000000000000", 0, 0,
+                 "76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7da41597c5157488d7724e03fb8d84a376a43b"
+                 "8f41518a11cc387b669b2ee6586");
+    TestChaCha20("0000000000000000000000000000000000000000000000000000000000000001", 0, 0,
+                 "4540f05a9f1fb296d7736e7b208e3c96eb4fe1834688d2604f450952ed432d41bbe2a0b6ea7566d2a5d1e7e20d42af2c53d79"
+                 "2b1c43fea817e9ad275ae546963");
+    TestChaCha20("0000000000000000000000000000000000000000000000000000000000000000", 0x0100000000000000ULL, 0,
+                 "de9cba7bf3d69ef5e786dc63973f653a0b49e015adbff7134fcb7df137821031e85a050278a7084527214f73efc7fa5b52770"
+                 "62eb7a0433e445f41e3");
+    TestChaCha20("0000000000000000000000000000000000000000000000000000000000000000", 1, 0,
+                 "ef3fdfd6c61578fbf5cf35bd3dd33b8009631634d21e42ac33960bd138e50d32111e4caf237ee53ca8ad6426194a88545ddc4"
+                 "97a0b466e7d6bbdb0041b2f586b");
+    TestChaCha20("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f", 0x0706050403020100ULL, 0,
+                 "f798a189f195e66982105ffb640bb7757f579da31602fc93ec01ac56f85ac3c134a4547b733b46413042c9440049176905d3b"
+                 "e59ea1c53f15916155c2be8241a38008b9a26bc35941e2444177c8ade6689de95264986d95889fb60e84629c9bd9a5acb1cc1"
+                 "18be563eb9b3a4a472f82e09a7e778492b562ef7130e88dfe031c79db9d4f7c7a899151b9a475032b63fc385245fe054e3dd5"
+                 "a97a5f576fe064025d3ce042c566ab2c507b138db853e3d6959660996546cc9c4a6eafdc777c040d70eaf46f76dad3979e5c5"
+                 "360c3317166a1c894c94a371876a94df7628fe4eaaf2ccb27d5aaae0ad7ad0f9d4b6ad3b54098746d4524d38407a6deb3ab78"
+                 "fab78c9");
+}
+
 BOOST_AUTO_TEST_SUITE_END()