| 1 | const { keccak256, ecdsaSign, ecdsaRecover, publicKeyToAddress } = require('./util/sign');
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| 2 | const format = require('./util/format');
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| 3 |
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| 4 | class Message {
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| 5 | /**
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| 6 | * Signs the hash with the privateKey.
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| 7 | *
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| 8 | * @param privateKey {string|Buffer}
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| 9 | * @param messageHash {string|Buffer}
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| 10 | * @return {string} The signature as hex string.
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| 11 | *
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| 12 | * @example
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| 13 | * > Message.sign(
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| 14 | '0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef', // privateKey
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| 15 | '0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba',
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| 16 | )
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| 17 | "0x6e913e2b76459f19ebd269b82b51a70e912e909b2f5c002312efc27bcc280f3c29134d382aad0dbd3f0ccc9f0eb8f1dbe3f90141d81574ebb6504156b0d7b95f01"
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| 18 | */
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| 19 | static sign(privateKey, messageHash) {
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| 20 | const { r, s, v } = ecdsaSign(format.hexBuffer(messageHash), format.hexBuffer(privateKey));
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| 21 | const buffer = Buffer.concat([r, s, format.hexBuffer(v)]);
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| 22 | return format.hex(buffer);
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| 23 | }
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| 24 |
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| 25 | /**
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| 26 | * Recovers the signers publicKey from the signature.
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| 27 | *
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| 28 | * @param signature {string|Buffer}
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| 29 | * @param messageHash {string|Buffer}
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| 30 | * @return {string} The publicKey as hex string.
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| 31 | *
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| 32 | * @example
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| 33 | * > Message.recover(
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| 34 | '0x6e913e2b76459f19ebd269b82b51a70e912e909b2f5c002312efc27bcc280f3c29134d382aad0dbd3f0ccc9f0eb8f1dbe3f90141d81574ebb6504156b0d7b95f01',
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| 35 | '0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba',
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| 36 | )
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| 37 | "0x4646ae5047316b4230d0086c8acec687f00b1cd9d1dc634f6cb358ac0a9a8ffffe77b4dd0a4bfb95851f3b7355c781dd60f8418fc8a65d14907aff47c903a559"
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| 38 | */
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| 39 | static recover(signature, messageHash) {
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| 40 | const signatureBuffer = format.hexBuffer(signature);
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| 41 | const r = signatureBuffer.slice(0, 32);
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| 42 | const s = signatureBuffer.slice(32, 64);
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| 43 | const v = signatureBuffer[64];
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| 44 | const buffer = ecdsaRecover(format.hexBuffer(messageHash), { r, s, v });
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| 45 | return format.publicKey(buffer);
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| 46 | }
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| 47 |
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| 48 | /**
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| 49 | * @param message {string}
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| 50 | * @return {Message}
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| 51 | *
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| 52 | * @example
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| 53 | * > msg = new Message('Hello World');
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| 54 | Message {
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| 55 | message: 'Hello World',
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| 56 | }
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| 57 | * > msg.sign('0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef');
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| 58 | Message {
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| 59 | message: 'Hello World',
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| 60 | signature: '0x6e913e2b76459f19ebd269b82b51a70e912e909b2f5c002312efc27bcc280f3c29134d382aad0dbd3f0ccc9f0eb8f1dbe3f90141d81574ebb6504156b0d7b95f01'
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| 61 | }
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| 62 | * > msg.signature
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| 63 | "0x6e913e2b76459f19ebd269b82b51a70e912e909b2f5c002312efc27bcc280f3c29134d382aad0dbd3f0ccc9f0eb8f1dbe3f90141d81574ebb6504156b0d7b95f01"
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| 64 | * > msg.hash
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| 65 | "0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba"
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| 66 | * > msg.from
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| 67 | "0x1cad0b19bb29d4674531d6f115237e16afce377c"
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| 68 | * > msg.r
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| 69 | "0x6e913e2b76459f19ebd269b82b51a70e912e909b2f5c002312efc27bcc280f3c"
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| 70 | * > msg.s
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| 71 | "0x29134d382aad0dbd3f0ccc9f0eb8f1dbe3f90141d81574ebb6504156b0d7b95f"
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| 72 | * > msg.v
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| 73 | 1
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| 74 | */
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| 75 | constructor(message) {
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| 76 | this.message = message;
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| 77 | }
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| 78 |
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| 79 | /**
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| 80 | * Getter of message hash include signature.
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| 81 | *
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| 82 | * > Note: calculate every time.
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| 83 | *
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| 84 | * @return {string}
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| 85 | */
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| 86 | get hash() {
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| 87 | return format.hex(keccak256(Buffer.from(this.message)));
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| 88 | }
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| 89 |
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| 90 | /**
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| 91 | * Getter of sender address.
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| 92 | *
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| 93 | * > Note: calculate every time.
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| 94 | *
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| 95 | * @return {string|undefined} If ECDSA recover success return address, else return undefined.
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| 96 | */
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| 97 | get from() {
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| 98 | try {
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| 99 | const publicKey = Message.recover(this.signature, this.hash);
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| 100 | return format.address(publicKeyToAddress(format.hexBuffer(publicKey)));
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| 101 | } catch (e) {
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| 102 | return undefined;
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| 103 | }
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| 104 | }
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| 105 |
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| 106 | /**
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| 107 | * Sign message and set 'r','s','v' and 'hash'.
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| 108 | *
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| 109 | * @param privateKey {string} - Private key hex string.
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| 110 | * @return {Message}
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| 111 | */
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| 112 | sign(privateKey) {
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| 113 | this.signature = Message.sign(privateKey, this.hash);
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| 114 | return this;
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| 115 | }
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| 116 |
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| 117 | get r() {
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| 118 | try {
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| 119 | return this.signature.slice(0, 2 + 64);
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| 120 | } catch (e) {
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| 121 | return undefined;
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| 122 | }
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| 123 | }
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| 124 |
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| 125 | get s() {
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| 126 | try {
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| 127 | return `0x${this.signature.slice(2 + 64, 2 + 128)}`;
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| 128 | } catch (e) {
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| 129 | return undefined;
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| 130 | }
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| 131 | }
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| 132 |
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| 133 | get v() {
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| 134 | try {
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| 135 | return parseInt(this.signature.slice(2 + 128, 2 + 130), 16);
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| 136 | } catch (e) {
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| 137 | return undefined;
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| 138 | }
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| 139 | }
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| 140 | }
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| 141 |
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| 142 | module.exports = Message;
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