Merge commit 'a545127fbccef4ee674d18d43732ce00ba97f782' as 'src/crypto/ctaes'

6 files changed, 939 insertions, 0 deletions

diff --git a/src/crypto/ctaes/COPYING b/src/crypto/ctaes/COPYING
new file mode 100644
index 0000000000..415b202a2a
--- /dev/null
+++ b/src/crypto/ctaes/COPYING
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Pieter Wuille
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/src/crypto/ctaes/README.md b/src/crypto/ctaes/README.md
new file mode 100644
index 0000000000..0e7fe17751
--- /dev/null
+++ b/src/crypto/ctaes/README.md
@@ -0,0 +1,41 @@
+ctaes
+=====
+
+Simple C module for constant-time AES encryption and decryption.
+
+Features:
+* Simple, pure C code without any dependencies.
+* No tables or data-dependent branches whatsoever, but using bit sliced approach from https://eprint.iacr.org/2009/129.pdf.
+* Very small object code: slightly over 4k of executable code when compiled with -Os.
+* Slower than implementations based on precomputed tables or specialized instructions, but can do ~15 MB/s on modern CPUs.
+
+Performance
+-----------
+
+Compiled with GCC 5.3.1 with -O3, on an Intel(R) Core(TM) i7-4800MQ CPU, numbers in CPU cycles:
+
+| Algorithm | Key schedule | Encryption per byte | Decryption per byte |
+| --------- | ------------:| -------------------:| -------------------:|
+| AES-128   |         2.8k |                 154 |                 161 |
+| AES-192   |         3.1k |                 169 |                 181 |
+| AES-256   |         4.0k |                 191 |                 203 |
+
+Build steps
+-----------
+
+Object code:
+
+    $ gcc -O3 ctaes.c -c -o ctaes.o
+
+Tests:
+
+    $ gcc -O3 ctaes.c test.c -o test
+
+Benchmark:
+
+    $ gcc -O3 ctaes.c bench.c -o bench
+
+Review
+------
+
+Results of a formal review of the code can be found in http://bitcoin.sipa.be/ctaes/review.zip
diff --git a/src/crypto/ctaes/bench.c b/src/crypto/ctaes/bench.c
new file mode 100644
index 0000000000..a86df496c8
--- /dev/null
+++ b/src/crypto/ctaes/bench.c
@@ -0,0 +1,170 @@
+#include <stdio.h>
+#include <math.h>
+#include "sys/time.h"
+
+#include "ctaes.h"
+
+static double gettimedouble(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return tv.tv_usec * 0.000001 + tv.tv_sec;
+}
+
+static void print_number(double x) {
+    double y = x;
+    int c = 0;
+    if (y < 0.0) {
+        y = -y;
+    }
+    while (y < 100.0) {
+        y *= 10.0;
+        c++;
+    }
+    printf("%.*f", c, x);
+}
+
+static void run_benchmark(char *name, void (*benchmark)(void*), void (*setup)(void*), void (*teardown)(void*), void* data, int count, int iter) {
+    int i;
+    double min = HUGE_VAL;
+    double sum = 0.0;
+    double max = 0.0;
+    for (i = 0; i < count; i++) {
+        double begin, total;
+        if (setup != NULL) {
+            setup(data);
+        }
+        begin = gettimedouble();
+        benchmark(data);
+        total = gettimedouble() - begin;
+        if (teardown != NULL) {
+            teardown(data);
+        }
+        if (total < min) {
+            min = total;
+        }
+        if (total > max) {
+            max = total;
+        }
+        sum += total;
+    }
+    printf("%s: min ", name);
+    print_number(min * 1000000000.0 / iter);
+    printf("ns / avg ");
+    print_number((sum / count) * 1000000000.0 / iter);
+    printf("ns / max ");
+    print_number(max * 1000000000.0 / iter);
+    printf("ns\n");
+}
+
+static void bench_AES128_init(void* data) {
+    AES128_ctx* ctx = (AES128_ctx*)data;
+    int i;
+    for (i = 0; i < 50000; i++) {
+        AES128_init(ctx, (unsigned char*)ctx);
+    }
+}
+
+static void bench_AES128_encrypt_setup(void* data) {
+    AES128_ctx* ctx = (AES128_ctx*)data;
+    static const unsigned char key[16] = {0};
+    AES128_init(ctx, key);
+}
+
+static void bench_AES128_encrypt(void* data) {
+    const AES128_ctx* ctx = (const AES128_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES128_encrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+static void bench_AES128_decrypt(void* data) {
+    const AES128_ctx* ctx = (const AES128_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES128_decrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+static void bench_AES192_init(void* data) {
+    AES192_ctx* ctx = (AES192_ctx*)data;
+    int i;
+    for (i = 0; i < 50000; i++) {
+        AES192_init(ctx, (unsigned char*)ctx);
+    }
+}
+
+static void bench_AES192_encrypt_setup(void* data) {
+    AES192_ctx* ctx = (AES192_ctx*)data;
+    static const unsigned char key[16] = {0};
+    AES192_init(ctx, key);
+}
+
+static void bench_AES192_encrypt(void* data) {
+    const AES192_ctx* ctx = (const AES192_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES192_encrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+static void bench_AES192_decrypt(void* data) {
+    const AES192_ctx* ctx = (const AES192_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES192_decrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+static void bench_AES256_init(void* data) {
+    AES256_ctx* ctx = (AES256_ctx*)data;
+    int i;
+    for (i = 0; i < 50000; i++) {
+        AES256_init(ctx, (unsigned char*)ctx);
+    }
+}
+
+
+static void bench_AES256_encrypt_setup(void* data) {
+    AES256_ctx* ctx = (AES256_ctx*)data;
+    static const unsigned char key[16] = {0};
+    AES256_init(ctx, key);
+}
+
+static void bench_AES256_encrypt(void* data) {
+    const AES256_ctx* ctx = (const AES256_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES256_encrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+static void bench_AES256_decrypt(void* data) {
+    const AES256_ctx* ctx = (const AES256_ctx*)data;
+    unsigned char scratch[16] = {0};
+    int i;
+    for (i = 0; i < 4000000 / 16; i++) {
+        AES256_decrypt(ctx, 1, scratch, scratch);
+    }
+}
+
+int main(void) {
+    AES128_ctx ctx128;
+    AES192_ctx ctx192;
+    AES256_ctx ctx256;
+    run_benchmark("aes128_init", bench_AES128_init, NULL, NULL, &ctx128, 20, 50000);
+    run_benchmark("aes128_encrypt_byte", bench_AES128_encrypt, bench_AES128_encrypt_setup, NULL, &ctx128, 20, 4000000);
+    run_benchmark("aes128_decrypt_byte", bench_AES128_decrypt, bench_AES128_encrypt_setup, NULL, &ctx128, 20, 4000000);
+    run_benchmark("aes192_init", bench_AES192_init, NULL, NULL, &ctx192, 20, 50000);
+    run_benchmark("aes192_encrypt_byte", bench_AES192_encrypt, bench_AES192_encrypt_setup, NULL, &ctx192, 20, 4000000);
+    run_benchmark("aes192_decrypt_byte", bench_AES192_decrypt, bench_AES192_encrypt_setup, NULL, &ctx192, 20, 4000000);
+    run_benchmark("aes256_init", bench_AES256_init, NULL, NULL, &ctx256, 20, 50000);
+    run_benchmark("aes256_encrypt_byte", bench_AES256_encrypt, bench_AES256_encrypt_setup, NULL, &ctx256, 20, 4000000);
+    run_benchmark("aes256_decrypt_byte", bench_AES256_decrypt, bench_AES256_encrypt_setup, NULL, &ctx256, 20, 4000000);
+    return 0;
+}
diff --git a/src/crypto/ctaes/ctaes.c b/src/crypto/ctaes/ctaes.c
new file mode 100644
index 0000000000..2389fc0bb2
--- /dev/null
+++ b/src/crypto/ctaes/ctaes.c
@@ -0,0 +1,556 @@
+ /*********************************************************************
+ * Copyright (c) 2016 Pieter Wuille                                   *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+/* Constant time, unoptimized, concise, plain C, AES implementation
+ * Based On:
+ *   Emilia Kasper and Peter Schwabe, Faster and Timing-Attack Resistant AES-GCM
+ *   http://www.iacr.org/archive/ches2009/57470001/57470001.pdf
+ * But using 8 16-bit integers representing a single AES state rather than 8 128-bit
+ * integers representing 8 AES states.
+ */
+
+#include "ctaes.h"
+
+/* Slice variable slice_i contains the i'th bit of the 16 state variables in this order:
+ *  0  1  2  3
+ *  4  5  6  7
+ *  8  9 10 11
+ * 12 13 14 15
+ */
+
+/** Convert a byte to sliced form, storing it corresponding to given row and column in s */
+static void LoadByte(AES_state* s, unsigned char byte, int r, int c) {
+    int i;
+    for (i = 0; i < 8; i++) {
+        s->slice[i] |= (byte & 1) << (r * 4 + c);
+        byte >>= 1;
+    }
+}
+
+/** Load 16 bytes of data into 8 sliced integers */
+static void LoadBytes(AES_state *s, const unsigned char* data16) {
+    int c;
+    for (c = 0; c < 4; c++) {
+        int r;
+        for (r = 0; r < 4; r++) {
+            LoadByte(s, *(data16++), r, c);
+        }
+    }
+}
+
+/** Convert 8 sliced integers into 16 bytes of data */
+static void SaveBytes(unsigned char* data16, const AES_state *s) {
+    int c;
+    for (c = 0; c < 4; c++) {
+        int r;
+        for (r = 0; r < 4; r++) {
+            int b;
+            uint8_t v = 0;
+            for (b = 0; b < 8; b++) {
+                v |= ((s->slice[b] >> (r * 4 + c)) & 1) << b;
+            }
+            *(data16++) = v;
+        }
+    }
+}
+
+/* S-box implementation based on the gate logic from:
+ *   Joan Boyar and Rene Peralta, A depth-16 circuit for the AES S-box.
+ *   https://eprint.iacr.org/2011/332.pdf
+*/
+static void SubBytes(AES_state *s, int inv) {
+    /* Load the bit slices */
+    uint16_t U0 = s->slice[7], U1 = s->slice[6], U2 = s->slice[5], U3 = s->slice[4];
+    uint16_t U4 = s->slice[3], U5 = s->slice[2], U6 = s->slice[1], U7 = s->slice[0];
+
+    uint16_t T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16;
+    uint16_t T17, T18, T19, T20, T21, T22, T23, T24, T25, T26, T27, D;
+    uint16_t M1, M6, M11, M13, M15, M20, M21, M22, M23, M25, M37, M38, M39, M40;
+    uint16_t M41, M42, M43, M44, M45, M46, M47, M48, M49, M50, M51, M52, M53, M54;
+    uint16_t M55, M56, M57, M58, M59, M60, M61, M62, M63;
+
+    if (inv) {
+        uint16_t R5, R13, R17, R18, R19;
+        /* Undo linear postprocessing */
+        T23 = U0 ^ U3;
+        T22 = ~(U1 ^ U3);
+        T2 = ~(U0 ^ U1);
+        T1 = U3 ^ U4;
+        T24 = ~(U4 ^ U7);
+        R5 = U6 ^ U7;
+        T8 = ~(U1 ^ T23);
+        T19 = T22 ^ R5;
+        T9 = ~(U7 ^ T1);
+        T10 = T2 ^ T24;
+        T13 = T2 ^ R5;
+        T3 = T1 ^ R5;
+        T25 = ~(U2 ^ T1);
+        R13 = U1 ^ U6;
+        T17 = ~(U2 ^ T19);
+        T20 = T24 ^ R13;
+        T4 = U4 ^ T8;
+        R17 = ~(U2 ^ U5);
+        R18 = ~(U5 ^ U6);
+        R19 = ~(U2 ^ U4);
+        D = U0 ^ R17;
+        T6 = T22 ^ R17;
+        T16 = R13 ^ R19;
+        T27 = T1 ^ R18;
+        T15 = T10 ^ T27;
+        T14 = T10 ^ R18;
+        T26 = T3 ^ T16;
+    } else {
+        /* Linear preprocessing. */
+        T1 = U0 ^ U3;
+        T2 = U0 ^ U5;
+        T3 = U0 ^ U6;
+        T4 = U3 ^ U5;
+        T5 = U4 ^ U6;
+        T6 = T1 ^ T5;
+        T7 = U1 ^ U2;
+        T8 = U7 ^ T6;
+        T9 = U7 ^ T7;
+        T10 = T6 ^ T7;
+        T11 = U1 ^ U5;
+        T12 = U2 ^ U5;
+        T13 = T3 ^ T4;
+        T14 = T6 ^ T11;
+        T15 = T5 ^ T11;
+        T16 = T5 ^ T12;
+        T17 = T9 ^ T16;
+        T18 = U3 ^ U7;
+        T19 = T7 ^ T18;
+        T20 = T1 ^ T19;
+        T21 = U6 ^ U7;
+        T22 = T7 ^ T21;
+        T23 = T2 ^ T22;
+        T24 = T2 ^ T10;
+        T25 = T20 ^ T17;
+        T26 = T3 ^ T16;
+        T27 = T1 ^ T12;
+        D = U7;
+    }
+
+    /* Non-linear transformation (identical to the code in SubBytes) */
+    M1 = T13 & T6;
+    M6 = T3 & T16;
+    M11 = T1 & T15;
+    M13 = (T4 & T27) ^ M11;
+    M15 = (T2 & T10) ^ M11;
+    M20 = T14 ^ M1 ^ (T23 & T8) ^ M13;
+    M21 = (T19 & D) ^ M1 ^ T24 ^ M15;
+    M22 = T26 ^ M6 ^ (T22 & T9) ^ M13;
+    M23 = (T20 & T17) ^ M6 ^ M15 ^ T25;
+    M25 = M22 & M20;
+    M37 = M21 ^ ((M20 ^ M21) & (M23 ^ M25));
+    M38 = M20 ^ M25 ^ (M21 | (M20 & M23));
+    M39 = M23 ^ ((M22 ^ M23) & (M21 ^ M25));
+    M40 = M22 ^ M25 ^ (M23 | (M21 & M22));
+    M41 = M38 ^ M40;
+    M42 = M37 ^ M39;
+    M43 = M37 ^ M38;
+    M44 = M39 ^ M40;
+    M45 = M42 ^ M41;
+    M46 = M44 & T6;
+    M47 = M40 & T8;
+    M48 = M39 & D;
+    M49 = M43 & T16;
+    M50 = M38 & T9;
+    M51 = M37 & T17;
+    M52 = M42 & T15;
+    M53 = M45 & T27;
+    M54 = M41 & T10;
+    M55 = M44 & T13;
+    M56 = M40 & T23;
+    M57 = M39 & T19;
+    M58 = M43 & T3;
+    M59 = M38 & T22;
+    M60 = M37 & T20;
+    M61 = M42 & T1;
+    M62 = M45 & T4;
+    M63 = M41 & T2;
+
+    if (inv){
+        /* Undo linear preprocessing */
+        uint16_t P0 = M52 ^ M61;
+        uint16_t P1 = M58 ^ M59;
+        uint16_t P2 = M54 ^ M62;
+        uint16_t P3 = M47 ^ M50;
+        uint16_t P4 = M48 ^ M56;
+        uint16_t P5 = M46 ^ M51;
+        uint16_t P6 = M49 ^ M60;
+        uint16_t P7 = P0 ^ P1;
+        uint16_t P8 = M50 ^ M53;
+        uint16_t P9 = M55 ^ M63;
+        uint16_t P10 = M57 ^ P4;
+        uint16_t P11 = P0 ^ P3;
+        uint16_t P12 = M46 ^ M48;
+        uint16_t P13 = M49 ^ M51;
+        uint16_t P14 = M49 ^ M62;
+        uint16_t P15 = M54 ^ M59;
+        uint16_t P16 = M57 ^ M61;
+        uint16_t P17 = M58 ^ P2;
+        uint16_t P18 = M63 ^ P5;
+        uint16_t P19 = P2 ^ P3;
+        uint16_t P20 = P4 ^ P6;
+        uint16_t P22 = P2 ^ P7;
+        uint16_t P23 = P7 ^ P8;
+        uint16_t P24 = P5 ^ P7;
+        uint16_t P25 = P6 ^ P10;
+        uint16_t P26 = P9 ^ P11;
+        uint16_t P27 = P10 ^ P18;
+        uint16_t P28 = P11 ^ P25;
+        uint16_t P29 = P15 ^ P20;
+        s->slice[7] = P13 ^ P22;
+        s->slice[6] = P26 ^ P29;
+        s->slice[5] = P17 ^ P28;
+        s->slice[4] = P12 ^ P22;
+        s->slice[3] = P23 ^ P27;
+        s->slice[2] = P19 ^ P24;
+        s->slice[1] = P14 ^ P23;
+        s->slice[0] = P9 ^ P16;
+    } else {
+        /* Linear postprocessing */
+        uint16_t L0 = M61 ^ M62;
+        uint16_t L1 = M50 ^ M56;
+        uint16_t L2 = M46 ^ M48;
+        uint16_t L3 = M47 ^ M55;
+        uint16_t L4 = M54 ^ M58;
+        uint16_t L5 = M49 ^ M61;
+        uint16_t L6 = M62 ^ L5;
+        uint16_t L7 = M46 ^ L3;
+        uint16_t L8 = M51 ^ M59;
+        uint16_t L9 = M52 ^ M53;
+        uint16_t L10 = M53 ^ L4;
+        uint16_t L11 = M60 ^ L2;
+        uint16_t L12 = M48 ^ M51;
+        uint16_t L13 = M50 ^ L0;
+        uint16_t L14 = M52 ^ M61;
+        uint16_t L15 = M55 ^ L1;
+        uint16_t L16 = M56 ^ L0;
+        uint16_t L17 = M57 ^ L1;
+        uint16_t L18 = M58 ^ L8;
+        uint16_t L19 = M63 ^ L4;
+        uint16_t L20 = L0 ^ L1;
+        uint16_t L21 = L1 ^ L7;
+        uint16_t L22 = L3 ^ L12;
+        uint16_t L23 = L18 ^ L2;
+        uint16_t L24 = L15 ^ L9;
+        uint16_t L25 = L6 ^ L10;
+        uint16_t L26 = L7 ^ L9;
+        uint16_t L27 = L8 ^ L10;
+        uint16_t L28 = L11 ^ L14;
+        uint16_t L29 = L11 ^ L17;
+        s->slice[7] = L6 ^ L24;
+        s->slice[6] = ~(L16 ^ L26);
+        s->slice[5] = ~(L19 ^ L28);
+        s->slice[4] = L6 ^ L21;
+        s->slice[3] = L20 ^ L22;
+        s->slice[2] = L25 ^ L29;
+        s->slice[1] = ~(L13 ^ L27);
+        s->slice[0] = ~(L6 ^ L23);
+    }
+}
+
+#define BIT_RANGE(from,to) (((1 << ((to) - (from))) - 1) << (from))
+
+#define BIT_RANGE_LEFT(x,from,to,shift) (((x) & BIT_RANGE((from), (to))) << (shift))
+#define BIT_RANGE_RIGHT(x,from,to,shift) (((x) & BIT_RANGE((from), (to))) >> (shift))
+
+static void ShiftRows(AES_state* s) {
+    int i;
+    for (i = 0; i < 8; i++) {
+        uint16_t v = s->slice[i];
+        s->slice[i] =
+            (v & BIT_RANGE(0, 4)) |
+            BIT_RANGE_LEFT(v, 4, 5, 3) | BIT_RANGE_RIGHT(v, 5, 8, 1) |
+            BIT_RANGE_LEFT(v, 8, 10, 2) | BIT_RANGE_RIGHT(v, 10, 12, 2) |
+            BIT_RANGE_LEFT(v, 12, 15, 1) | BIT_RANGE_RIGHT(v, 15, 16, 3);
+    }
+}
+
+static void InvShiftRows(AES_state* s) {
+    int i;
+    for (i = 0; i < 8; i++) {
+        uint16_t v = s->slice[i];
+        s->slice[i] =
+            (v & BIT_RANGE(0, 4)) |
+            BIT_RANGE_LEFT(v, 4, 7, 1) | BIT_RANGE_RIGHT(v, 7, 8, 3) |
+            BIT_RANGE_LEFT(v, 8, 10, 2) | BIT_RANGE_RIGHT(v, 10, 12, 2) |
+            BIT_RANGE_LEFT(v, 12, 13, 3) | BIT_RANGE_RIGHT(v, 13, 16, 1);
+    }
+}
+
+#define ROT(x,b) (((x) >> ((b) * 4)) | ((x) << ((4-(b)) * 4)))
+
+static void MixColumns(AES_state* s, int inv) {
+    /* The MixColumns transform treats the bytes of the columns of the state as
+     * coefficients of a 3rd degree polynomial over GF(2^8) and multiplies them
+     * by the fixed polynomial a(x) = {03}x^3 + {01}x^2 + {01}x + {02}, modulo
+     * x^4 + {01}.
+     *
+     * In the inverse transform, we multiply by the inverse of a(x),
+     * a^-1(x) = {0b}x^3 + {0d}x^2 + {09}x + {0e}. This is equal to
+     * a(x) * ({04}x^2 + {05}), so we can reuse the forward transform's code
+     * (found in OpenSSL's bsaes-x86_64.pl, attributed to Jussi Kivilinna)
+     *
+     * In the bitsliced representation, a multiplication of every column by x
+     * mod x^4 + 1 is simply a right rotation.
+     */
+
+    /* Shared for both directions is a multiplication by a(x), which can be
+     * rewritten as (x^3 + x^2 + x) + {02}*(x^3 + {01}).
+     *
+     * First compute s into the s? variables, (x^3 + {01}) * s into the s?_01
+     * variables and (x^3 + x^2 + x)*s into the s?_123 variables.
+     */
+    uint16_t s0 = s->slice[0], s1 = s->slice[1], s2 = s->slice[2], s3 = s->slice[3];
+    uint16_t s4 = s->slice[4], s5 = s->slice[5], s6 = s->slice[6], s7 = s->slice[7];
+    uint16_t s0_01 = s0 ^ ROT(s0, 1), s0_123 = ROT(s0_01, 1) ^ ROT(s0, 3);
+    uint16_t s1_01 = s1 ^ ROT(s1, 1), s1_123 = ROT(s1_01, 1) ^ ROT(s1, 3);
+    uint16_t s2_01 = s2 ^ ROT(s2, 1), s2_123 = ROT(s2_01, 1) ^ ROT(s2, 3);
+    uint16_t s3_01 = s3 ^ ROT(s3, 1), s3_123 = ROT(s3_01, 1) ^ ROT(s3, 3);
+    uint16_t s4_01 = s4 ^ ROT(s4, 1), s4_123 = ROT(s4_01, 1) ^ ROT(s4, 3);
+    uint16_t s5_01 = s5 ^ ROT(s5, 1), s5_123 = ROT(s5_01, 1) ^ ROT(s5, 3);
+    uint16_t s6_01 = s6 ^ ROT(s6, 1), s6_123 = ROT(s6_01, 1) ^ ROT(s6, 3);
+    uint16_t s7_01 = s7 ^ ROT(s7, 1), s7_123 = ROT(s7_01, 1) ^ ROT(s7, 3);
+    /* Now compute s = s?_123 + {02} * s?_01. */
+    s->slice[0] = s7_01 ^ s0_123;
+    s->slice[1] = s7_01 ^ s0_01 ^ s1_123;
+    s->slice[2] = s1_01 ^ s2_123;
+    s->slice[3] = s7_01 ^ s2_01 ^ s3_123;
+    s->slice[4] = s7_01 ^ s3_01 ^ s4_123;
+    s->slice[5] = s4_01 ^ s5_123;
+    s->slice[6] = s5_01 ^ s6_123;
+    s->slice[7] = s6_01 ^ s7_123;
+    if (inv) {
+        /* In the reverse direction, we further need to multiply by
+         * {04}x^2 + {05}, which can be written as {04} * (x^2 + {01}) + {01}.
+         *
+         * First compute (x^2 + {01}) * s into the t?_02 variables: */
+        uint16_t t0_02 = s->slice[0] ^ ROT(s->slice[0], 2);
+        uint16_t t1_02 = s->slice[1] ^ ROT(s->slice[1], 2);
+        uint16_t t2_02 = s->slice[2] ^ ROT(s->slice[2], 2);
+        uint16_t t3_02 = s->slice[3] ^ ROT(s->slice[3], 2);
+        uint16_t t4_02 = s->slice[4] ^ ROT(s->slice[4], 2);
+        uint16_t t5_02 = s->slice[5] ^ ROT(s->slice[5], 2);
+        uint16_t t6_02 = s->slice[6] ^ ROT(s->slice[6], 2);
+        uint16_t t7_02 = s->slice[7] ^ ROT(s->slice[7], 2);
+        /* And then update s += {04} * t?_02 */
+        s->slice[0] ^= t6_02;
+        s->slice[1] ^= t6_02 ^ t7_02;
+        s->slice[2] ^= t0_02 ^ t7_02;
+        s->slice[3] ^= t1_02 ^ t6_02;
+        s->slice[4] ^= t2_02 ^ t6_02 ^ t7_02;
+        s->slice[5] ^= t3_02 ^ t7_02;
+        s->slice[6] ^= t4_02;
+        s->slice[7] ^= t5_02;
+    }
+}
+
+static void AddRoundKey(AES_state* s, const AES_state* round) {
+    int b;
+    for (b = 0; b < 8; b++) {
+        s->slice[b] ^= round->slice[b];
+    }
+}
+
+/** column_0(s) = column_c(a) */
+static void GetOneColumn(AES_state* s, const AES_state* a, int c) {
+    int b;
+    for (b = 0; b < 8; b++) {
+        s->slice[b] = (a->slice[b] >> c) & 0x1111;
+    }
+}
+
+/** column_c1(r) |= (column_0(s) ^= column_c2(a)) */
+static void KeySetupColumnMix(AES_state* s, AES_state* r, const AES_state* a, int c1, int c2) {
+    int b;
+    for (b = 0; b < 8; b++) {
+        r->slice[b] |= ((s->slice[b] ^= ((a->slice[b] >> c2) & 0x1111)) & 0x1111) << c1;
+    }
+}
+
+/** Rotate the rows in s one position upwards, and xor in r */
+static void KeySetupTransform(AES_state* s, const AES_state* r) {
+    int b;
+    for (b = 0; b < 8; b++) {
+        s->slice[b] = ((s->slice[b] >> 4) | (s->slice[b] << 12)) ^ r->slice[b];
+    }
+}
+
+/* Multiply the cells in s by x, as polynomials over GF(2) mod x^8 + x^4 + x^3 + x + 1 */
+static void MultX(AES_state* s) {
+    uint16_t top = s->slice[7];
+    s->slice[7] = s->slice[6];
+    s->slice[6] = s->slice[5];
+    s->slice[5] = s->slice[4];
+    s->slice[4] = s->slice[3] ^ top;
+    s->slice[3] = s->slice[2] ^ top;
+    s->slice[2] = s->slice[1];
+    s->slice[1] = s->slice[0] ^ top;
+    s->slice[0] = top;
+}
+
+/** Expand the cipher key into the key schedule.
+ *
+ *  state must be a pointer to an array of size nrounds + 1.
+ *  key must be a pointer to 4 * nkeywords bytes.
+ *
+ *  AES128 uses nkeywords = 4, nrounds = 10
+ *  AES192 uses nkeywords = 6, nrounds = 12
+ *  AES256 uses nkeywords = 8, nrounds = 14
+ */
+static void AES_setup(AES_state* rounds, const uint8_t* key, int nkeywords, int nrounds)
+{
+    int i;
+
+    /* The one-byte round constant */
+    AES_state rcon = {{1,0,0,0,0,0,0,0}};
+    /* The number of the word being generated, modulo nkeywords */
+    int pos = 0;
+    /* The column representing the word currently being processed */
+    AES_state column;
+
+    for (i = 0; i < nrounds + 1; i++) {
+        int b;
+        for (b = 0; b < 8; b++) {
+            rounds[i].slice[b] = 0;
+        }
+    }
+
+    /* The first nkeywords round columns are just taken from the key directly. */
+    for (i = 0; i < nkeywords; i++) {
+        int r;
+        for (r = 0; r < 4; r++) {
+            LoadByte(&rounds[i >> 2], *(key++), r, i & 3);
+        }
+    }
+
+    GetOneColumn(&column, &rounds[(nkeywords - 1) >> 2], (nkeywords - 1) & 3);
+
+    for (i = nkeywords; i < 4 * (nrounds + 1); i++) {
+        /* Transform column */
+        if (pos == 0) {
+            SubBytes(&column, 0);
+            KeySetupTransform(&column, &rcon);
+            MultX(&rcon);
+        } else if (nkeywords > 6 && pos == 4) {
+            SubBytes(&column, 0);
+        }
+        if (++pos == nkeywords) pos = 0;
+        KeySetupColumnMix(&column, &rounds[i >> 2], &rounds[(i - nkeywords) >> 2], i & 3, (i - nkeywords) & 3);
+    }
+}
+
+static void AES_encrypt(const AES_state* rounds, int nrounds, unsigned char* cipher16, const unsigned char* plain16) {
+    AES_state s = {{0}};
+    int round;
+
+    LoadBytes(&s, plain16);
+    AddRoundKey(&s, rounds++);
+
+    for (round = 1; round < nrounds; round++) {
+        SubBytes(&s, 0);
+        ShiftRows(&s);
+        MixColumns(&s, 0);
+        AddRoundKey(&s, rounds++);
+    }
+
+    SubBytes(&s, 0);
+    ShiftRows(&s);
+    AddRoundKey(&s, rounds);
+
+    SaveBytes(cipher16, &s);
+}
+
+static void AES_decrypt(const AES_state* rounds, int nrounds, unsigned char* plain16, const unsigned char* cipher16) {
+    /* Most AES decryption implementations use the alternate scheme
+     * (the Equivalent Inverse Cipher), which looks more like encryption, but
+     * needs different round constants. We can't reuse any code here anyway, so
+     * don't bother. */
+    AES_state s = {{0}};
+    int round;
+
+    rounds += nrounds;
+
+    LoadBytes(&s, cipher16);
+    AddRoundKey(&s, rounds--);
+
+    for (round = 1; round < nrounds; round++) {
+        InvShiftRows(&s);
+        SubBytes(&s, 1);
+        AddRoundKey(&s, rounds--);
+        MixColumns(&s, 1);
+    }
+
+    InvShiftRows(&s);
+    SubBytes(&s, 1);
+    AddRoundKey(&s, rounds);
+
+    SaveBytes(plain16, &s);
+}
+
+void AES128_init(AES128_ctx* ctx, const unsigned char* key16) {
+    AES_setup(ctx->rk, key16, 4, 10);
+}
+
+void AES128_encrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
+    while (blocks--) {
+        AES_encrypt(ctx->rk, 10, cipher16, plain16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+}
+
+void AES128_decrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
+    while (blocks--) {
+        AES_decrypt(ctx->rk, 10, plain16, cipher16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+}
+
+void AES192_init(AES192_ctx* ctx, const unsigned char* key24) {
+    AES_setup(ctx->rk, key24, 6, 12);
+}
+
+void AES192_encrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
+    while (blocks--) {
+        AES_encrypt(ctx->rk, 12, cipher16, plain16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+
+}
+
+void AES192_decrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
+    while (blocks--) {
+        AES_decrypt(ctx->rk, 12, plain16, cipher16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+}
+
+void AES256_init(AES256_ctx* ctx, const unsigned char* key32) {
+    AES_setup(ctx->rk, key32, 8, 14);
+}
+
+void AES256_encrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
+    while (blocks--) {
+        AES_encrypt(ctx->rk, 14, cipher16, plain16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+}
+
+void AES256_decrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
+    while (blocks--) {
+        AES_decrypt(ctx->rk, 14, plain16, cipher16);
+        cipher16 += 16;
+        plain16 += 16;
+    }
+}
diff --git a/src/crypto/ctaes/ctaes.h b/src/crypto/ctaes/ctaes.h
new file mode 100644
index 0000000000..2f0af04216
--- /dev/null
+++ b/src/crypto/ctaes/ctaes.h
@@ -0,0 +1,41 @@
+ /*********************************************************************
+ * Copyright (c) 2016 Pieter Wuille                                   *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _CTAES_H_
+#define _CTAES_H_ 1
+
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+    uint16_t slice[8];
+} AES_state;
+
+typedef struct {
+    AES_state rk[11];
+} AES128_ctx;
+
+typedef struct {
+    AES_state rk[13];
+} AES192_ctx;
+
+typedef struct {
+    AES_state rk[15];
+} AES256_ctx;
+
+void AES128_init(AES128_ctx* ctx, const unsigned char* key16);
+void AES128_encrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16);
+void AES128_decrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16);
+
+void AES192_init(AES192_ctx* ctx, const unsigned char* key24);
+void AES192_encrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16);
+void AES192_decrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16);
+
+void AES256_init(AES256_ctx* ctx, const unsigned char* key32);
+void AES256_encrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16);
+void AES256_decrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16);
+
+#endif
diff --git a/src/crypto/ctaes/test.c b/src/crypto/ctaes/test.c
new file mode 100644
index 0000000000..fce1696acd
--- /dev/null
+++ b/src/crypto/ctaes/test.c
@@ -0,0 +1,110 @@
+ /*********************************************************************
+ * Copyright (c) 2016 Pieter Wuille                                   *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#include "ctaes.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+typedef struct {
+    int keysize;
+    const char* key;
+    const char* plain;
+    const char* cipher;
+} ctaes_test;
+
+static const ctaes_test ctaes_tests[] = {
+    /* AES test vectors from FIPS 197. */
+    {128, "000102030405060708090a0b0c0d0e0f", "00112233445566778899aabbccddeeff", "69c4e0d86a7b0430d8cdb78070b4c55a"},
+    {192, "000102030405060708090a0b0c0d0e0f1011121314151617", "00112233445566778899aabbccddeeff", "dda97ca4864cdfe06eaf70a0ec0d7191"},
+    {256, "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f", "00112233445566778899aabbccddeeff", "8ea2b7ca516745bfeafc49904b496089"},
+
+    /* AES-ECB test vectors from NIST sp800-38a. */
+    {128, "2b7e151628aed2a6abf7158809cf4f3c", "6bc1bee22e409f96e93d7e117393172a", "3ad77bb40d7a3660a89ecaf32466ef97"},
+    {128, "2b7e151628aed2a6abf7158809cf4f3c", "ae2d8a571e03ac9c9eb76fac45af8e51", "f5d3d58503b9699de785895a96fdbaaf"},
+    {128, "2b7e151628aed2a6abf7158809cf4f3c", "30c81c46a35ce411e5fbc1191a0a52ef", "43b1cd7f598ece23881b00e3ed030688"},
+    {128, "2b7e151628aed2a6abf7158809cf4f3c", "f69f2445df4f9b17ad2b417be66c3710", "7b0c785e27e8ad3f8223207104725dd4"},
+    {192, "8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b", "6bc1bee22e409f96e93d7e117393172a", "bd334f1d6e45f25ff712a214571fa5cc"},
+    {192, "8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b", "ae2d8a571e03ac9c9eb76fac45af8e51", "974104846d0ad3ad7734ecb3ecee4eef"},
+    {192, "8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b", "30c81c46a35ce411e5fbc1191a0a52ef", "ef7afd2270e2e60adce0ba2face6444e"},
+    {192, "8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b", "f69f2445df4f9b17ad2b417be66c3710", "9a4b41ba738d6c72fb16691603c18e0e"},
+    {256, "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4", "6bc1bee22e409f96e93d7e117393172a", "f3eed1bdb5d2a03c064b5a7e3db181f8"},
+    {256, "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4", "ae2d8a571e03ac9c9eb76fac45af8e51", "591ccb10d410ed26dc5ba74a31362870"},
+    {256, "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4", "30c81c46a35ce411e5fbc1191a0a52ef", "b6ed21b99ca6f4f9f153e7b1beafed1d"},
+    {256, "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4", "f69f2445df4f9b17ad2b417be66c3710", "23304b7a39f9f3ff067d8d8f9e24ecc7"}
+};
+
+static void from_hex(unsigned char* data, int len, const char* hex) {
+    int p;
+    for (p = 0; p < len; p++) {
+        int v = 0;
+        int n;
+        for (n = 0; n < 2; n++) {
+            assert((*hex >= '0' && *hex <= '9') || (*hex >= 'a' && *hex <= 'f'));
+            if (*hex >= '0' && *hex <= '9') {
+                v |= (*hex - '0') << (4 * (1 - n));
+            } else {
+                v |= (*hex - 'a' + 10) << (4 * (1 - n));
+            }
+            hex++;
+        }
+        *(data++) = v;
+    }
+    assert(*hex == 0);
+}
+
+int main(void) {
+    int i;
+    int fail = 0;
+    for (i = 0; i < sizeof(ctaes_tests) / sizeof(ctaes_tests[0]); i++) {
+        unsigned char key[32], plain[16], cipher[16], ciphered[16], deciphered[16];
+        const ctaes_test* test = &ctaes_tests[i];
+        assert(test->keysize == 128 || test->keysize == 192 || test->keysize == 256);
+        from_hex(plain, 16, test->plain);
+        from_hex(cipher, 16, test->cipher);
+        switch (test->keysize) {
+            case 128: {
+                AES128_ctx ctx;
+                from_hex(key, 16, test->key);
+                AES128_init(&ctx, key);
+                AES128_encrypt(&ctx, 1, ciphered, plain);
+                AES128_decrypt(&ctx, 1, deciphered, cipher);
+                break;
+            }
+            case 192: {
+                AES192_ctx ctx;
+                from_hex(key, 24, test->key);
+                AES192_init(&ctx, key);
+                AES192_encrypt(&ctx, 1, ciphered, plain);
+                AES192_decrypt(&ctx, 1, deciphered, cipher);
+                break;
+            }
+            case 256: {
+                AES256_ctx ctx;
+                from_hex(key, 32, test->key);
+                AES256_init(&ctx, key);
+                AES256_encrypt(&ctx, 1, ciphered, plain);
+                AES256_decrypt(&ctx, 1, deciphered, cipher);
+                break;
+            }
+        }
+        if (memcmp(cipher, ciphered, 16)) {
+            fprintf(stderr, "E(key=\"%s\", plain=\"%s\") != \"%s\"\n", test->key, test->plain, test->cipher);
+            fail++;
+        }
+        if (memcmp(plain, deciphered, 16)) {
+            fprintf(stderr, "D(key=\"%s\", cipher=\"%s\") != \"%s\"\n", test->key, test->cipher, test->plain);
+            fail++;
+        }
+    }
+    if (fail == 0) {
+        fprintf(stderr, "All tests succesful\n");
+    } else {
+        fprintf(stderr, "%i tests failed\n", fail);
+    }
+    return (fail != 0);
+}