Merge pull request #1 from crema-labs/feat/key-expansion

feat: add key expansion and sbox logic

circuits/key_expansion.circom

@@ -0,0 +1,208 @@
+pragma circom 2.0.0;
+
+include "sbox128.circom";
+include "../node_modules/circomlib/circuits/comparators.circom";
+include "../node_modules/circomlib/circuits/bitify.circom";
+include "../node_modules/circomlib/circuits/gates.circom";
+
+//nk is the number of keys which can be 4, 6, 8 
+//nr is the number of rounds which can be 10, 12, 14
+template KeyExpansion(nk, nr) {
+    signal input key[nk * 4];
+
+    var totalWords = (4 * (nr + 1));
+    var effectiveRounds = (totalWords % nk == 0 ? totalWords - nk : totalWords) \ nk;
+    var leftoverWords = totalWords - (effectiveRounds * nk);
+
+    signal output keyExpanded[totalWords][4];
+
+    for (var i = 0; i < nk; i++) {
+        for (var j = 0; j < 4; j++) {
+            keyExpanded[i][j] <== key[(4 * i) + j];
+        }
+    }
+
+    component nextRound[effectiveRounds];
+
+    for (var round = 1; round <= effectiveRounds; round++) {
+        var outputWordLen = round == effectiveRounds ? leftoverWords : nk;
+        nextRound[round - 1] = NextRound(nk, outputWordLen);
+
+        for (var i = 0; i < nk; i++) {
+            for (var j = 0; j < 4; j++) {
+                nextRound[round - 1].key[i][j] <== keyExpanded[(round * nk) + i - nk][j];
+            }
+        }
+
+        nextRound[round - 1].round <== round;
+
+        for (var i = 0; i < outputWordLen; i++) {
+            for (var j = 0; j < 4; j++) {
+                keyExpanded[(round * nk) + i][j] <== nextRound[round - 1].nextKey[i][j];
+            }
+        }
+    }
+}
+
+//nk, output
+template NextRound(nk, o){
+    signal input key[nk][4]; 
+    signal input round;
+    signal output nextKey[o][4];
+
+    component rotateWord = RotateWord(1);
+    for (var i = 0; i < 4; i++) {
+        rotateWord.bytes[i] <== key[nk - 1][i];
+    }
+
+    component substituteWord[2];
+    substituteWord[0] = SubstituteWord();
+    substituteWord[0].bytes <== rotateWord.rotated;
+
+    component rcon = RCon();
+    rcon.round <== round; 
+
+    component xorWord[o + 1];
+    xorWord[0] = XorWord();
+    xorWord[0].bytes1 <== substituteWord[0].substituted;
+    xorWord[0].bytes2 <== rcon.out;
+
+    for (var i = 0; i < o; i++) {
+        xorWord[i+1] = XorWord();
+        if (i == 0) {
+            xorWord[i+1].bytes1 <== xorWord[0].out;
+        } else if(nk == 8 && i == 4) {
+            substituteWord[1] = SubstituteWord();
+            substituteWord[1].bytes <== nextKey[i - 1];
+            xorWord[i+1].bytes1 <== substituteWord[1].substituted;
+        } else {
+            xorWord[i+1].bytes1 <== nextKey[i-1];
+        }
+        xorWord[i+1].bytes2 <== key[i];
+
+        for (var j = 0; j < 4; j++) {
+            nextKey[i][j] <== xorWord[i+1].out[j];
+        }
+    }
+}
+
+
+template BytesToWords(n) {
+    assert(n % 4 == 0);
+    signal input bytes[n];
+    signal output words[n / 4][n];
+
+    for (var i = 0; i < n / 4; i++) {
+        for(var j = 0; j < 4; j++) {
+            words[i][j] <== bytes[i * 4 + j];
+        }
+    }
+}
+
+template RotateWord(rotation) {
+    assert(rotation < 4);
+    signal input bytes[4];
+    signal output rotated[4];
+
+    signal copy[rotation];
+
+    for(var i = 0; i < rotation; i++) {
+        copy[i] <== bytes[i];
+    }
+
+    for(var i = 0; i < 4 - rotation; i++) {
+        rotated[i] <== bytes[i + rotation];
+    }
+
+    for(var i = 4 - rotation; i < 4; i++) {
+        rotated[i] <== copy[i - 4 + rotation];
+    }
+}
+
+template SubstituteWord() {
+    signal input bytes[4];
+    signal output substituted[4];
+
+    component sbox[4];
+
+    for(var i = 0; i < 4; i++) {
+        sbox[i] = Sbox128();
+        sbox[i].in <== bytes[i];
+        substituted[i] <== sbox[i].out;
+    }
+}
+
+template RCon() {
+    signal input round;
+    signal output out[4];
+
+    var rcon[10][4] = [
+        [0x01, 0x00, 0x00, 0x00],
+        [0x02, 0x00, 0x00, 0x00],
+        [0x04, 0x00, 0x00, 0x00],
+        [0x08, 0x00, 0x00, 0x00],
+        [0x10, 0x00, 0x00, 0x00],
+        [0x20, 0x00, 0x00, 0x00],
+        [0x40, 0x00, 0x00, 0x00],
+        [0x80, 0x00, 0x00, 0x00],
+        [0x1b, 0x00, 0x00, 0x00],
+        [0x36, 0x00, 0x00, 0x00]
+    ];
+
+    component isEqual[10];
+    signal sum[10][4];
+
+    for (var i = 0; i < 10; i++) {
+        isEqual[i] = IsEqual();
+        isEqual[i].in[0] <== round - 1;
+        isEqual[i].in[1] <== i;
+    }
+
+    sum[0] <== [isEqual[0].out * rcon[0][0], isEqual[1].out * rcon[0][1], isEqual[2].out * rcon[0][2], isEqual[3].out * rcon[0][3]];
+    for (var i = 1; i < 10; i++) {
+        for (var j = 0; j < 4; j++) {
+            sum[i][j] <== sum[i - 1][j] + isEqual[i].out * rcon[i][j];
+        }
+    }
+
+    out <== sum[9];
+}
+
+template XorWord() {
+    signal input bytes1[4];
+    signal input bytes2[4];
+
+    component n2b[4 * 2];
+    component b2n[4];
+    component xor[4][8];
+
+    signal output out[4];
+
+    for(var i = 0; i < 4; i++) {
+        n2b[2 * i] = Num2Bits(8);
+        n2b[2 * i + 1] = Num2Bits(8);
+        n2b[2 * i].in <== bytes1[i];
+        n2b[2 * i + 1].in <== bytes2[i];
+        b2n[i] = Bits2Num(8);
+
+        for (var j = 0; j < 8; j++) {
+            xor[i][j] = XOR();
+            xor[i][j].a <== n2b[2 * i].out[j];
+            xor[i][j].b <== n2b[2 * i + 1].out[j];
+            b2n[i].in[j] <== xor[i][j].out;
+        }
+
+        out[i] <== b2n[i].out;
+    }
+}
+
+template WordSelector() {
+    signal input condition;
+    signal input bytes1[4];
+    signal input bytes2[4];
+    signal output out[4];
+
+    for (var i = 0; i < 4; i++) {
+        out[i] <== condition * (bytes1[i] - bytes2[i]) + bytes2[i];
+    }
+}

circuits/sbox128.circom

@@ -0,0 +1,29 @@
+pragma circom 2.0.0;
+
+include "circomlib/circuits/comparators.circom";
+
+template Sbox128() {
+    signal input in;
+    signal output out;
+
+    var sbox[16 * 16] = [
+        0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
+        0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
+        0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
+        0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
+        0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
+        0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
+        0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
+        0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
+        0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
+        0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
+        0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
+        0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
+        0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
+        0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
+        0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
+        0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
+    ];
+
+    out <-- sbox[in];
+}