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Add new LinearCodeAddressGenerator contract (#467)
* add new LinearCodeAddressGenerator contract * refactor code words into dictionary to improve extensibility * update assets * test address is not valid with other chain codewords * hide (invalid) code words behind chain * update assets * Apply suggestions from code review Co-authored-by: Tarak Ben Youssef <50252200+tarakby@users.noreply.github.com> * clean up * rename code word function * address at index is only valid in range [1 .. 2^45 - 1] * update assets * remove TODO, use bitshift * use maxIndex variable * add linear code address generator --------- Co-authored-by: Tarak Ben Youssef <50252200+tarakby@users.noreply.github.com>
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| /// LinearCodeAddressGenerator allows generating and validating Flow account addresses. | ||
| access(all) | ||
| contract LinearCodeAddressGenerator { | ||
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| access(all) | ||
| enum Chain: UInt8 { | ||
| access(all) | ||
| case Mainnet | ||
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| access(all) | ||
| case Testnet | ||
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| access(all) | ||
| case Transient | ||
| } | ||
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| /// Rows of the generator matrix G of the [64,45]-code used for Flow addresses. | ||
| /// G is a (k x n) matrix with coefficients in GF(2), each row is converted into | ||
| /// a big endian integer representation of the GF(2) raw vector. | ||
| /// G is used to generate the account addresses | ||
| access(self) | ||
| let generatorMatrixRows: [UInt64; 45] | ||
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| /// Columns of the parity-check matrix H of the [64,45]-code used for Flow addresses. | ||
| /// H is a (n x p) matrix with coefficients in GF(2), each column is converted into | ||
| /// a big endian integer representation of the GF(2) column vector. | ||
| /// H is used to verify a code word is a valid account address. | ||
| access(self) | ||
| let parityCheckMatrixColumns: [UInt64; 64] | ||
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| init() { | ||
| self.generatorMatrixRows = [ | ||
| 0xe467b9dd11fa00df, 0xf233dcee88fe0abe, 0xf919ee77447b7497, 0xfc8cf73ba23a260d, | ||
| 0xfe467b9dd11ee2a1, 0xff233dcee888d807, 0xff919ee774476ce6, 0x7fc8cf73ba231d10, | ||
| 0x3fe467b9dd11b183, 0x1ff233dcee8f96d6, 0x8ff919ee774757ba, 0x47fc8cf73ba2b331, | ||
| 0x23fe467b9dd27f6c, 0x11ff233dceee8e82, 0x88ff919ee775dd8f, 0x447fc8cf73b905e4, | ||
| 0xa23fe467b9de0d83, 0xd11ff233dce8d5a7, 0xe88ff919ee73c38a, 0x7447fc8cf73f171f, | ||
| 0xba23fe467b9dcb2b, 0xdd11ff233dcb0cb4, 0xee88ff919ee26c5d, 0x77447fc8cf775dd3, | ||
| 0x3ba23fe467b9b5a1, 0x9dd11ff233d9117a, 0xcee88ff919efa640, 0xe77447fc8cf3e297, | ||
| 0x73ba23fe467fabd2, 0xb9dd11ff233fb16c, 0xdcee88ff919adde7, 0xee77447fc8ceb196, | ||
| 0xf73ba23fe4621cd0, 0x7b9dd11ff2379ac3, 0x3dcee88ff91df46c, 0x9ee77447fc88e702, | ||
| 0xcf73ba23fe4131b6, 0x67b9dd11ff240f9a, 0x33dcee88ff90f9e0, 0x19ee77447fcff4e3, | ||
| 0x8cf73ba23fe64091, 0x467b9dd11ff115c7, 0x233dcee88ffdb735, 0x919ee77447fe2309, | ||
| 0xc8cf73ba23fdc736 | ||
| ] | ||
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| self.parityCheckMatrixColumns = [ | ||
| 0x00001, 0x00002, 0x00004, 0x00008, 0x00010, 0x00020, 0x00040, 0x00080, | ||
| 0x00100, 0x00200, 0x00400, 0x00800, 0x01000, 0x02000, 0x04000, 0x08000, | ||
| 0x10000, 0x20000, 0x40000, 0x7328d, 0x6689a, 0x6112f, 0x6084b, 0x433fd, | ||
| 0x42aab, 0x41951, 0x233ce, 0x22a81, 0x21948, 0x1ef60, 0x1deca, 0x1c639, | ||
| 0x1bdd8, 0x1a535, 0x194ac, 0x18c46, 0x1632b, 0x1529b, 0x14a43, 0x13184, | ||
| 0x12942, 0x118c1, 0x0f812, 0x0e027, 0x0d00e, 0x0c83c, 0x0b01d, 0x0a831, | ||
| 0x0982b, 0x07034, 0x0682a, 0x05819, 0x03807, 0x007d2, 0x00727, 0x0068e, | ||
| 0x0067c, 0x0059d, 0x004eb, 0x003b4, 0x0036a, 0x002d9, 0x001c7, 0x0003f | ||
| ] | ||
| } | ||
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| access(self) | ||
| fun invalidCodeWord(forChain chain: Chain): UInt64 { | ||
| switch chain { | ||
| case Chain.Mainnet: | ||
| return 0 | ||
| case Chain.Testnet: | ||
| return 0x6834ba37b3980209 | ||
| case Chain.Transient: | ||
| return 0x1cb159857af02018 | ||
| default: | ||
| panic("unsupported chain") | ||
| } | ||
| } | ||
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| access(self) | ||
| fun encodeWord(_ word: UInt64): UInt64 { | ||
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| // Multiply the index GF(2) vector by the code generator matrix | ||
| var codeWord: UInt64 = 0 | ||
| var word = word | ||
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| for generatorMatrixRow in self.generatorMatrixRows { | ||
| if word & 1 == 1 { | ||
| codeWord = codeWord ^ generatorMatrixRow | ||
| } | ||
| word = word >> 1 | ||
| } | ||
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| return codeWord | ||
| } | ||
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| /// Returns the address at the given index, for the given chain. | ||
| access(all) | ||
| fun address(at index: UInt64, chain: Chain): Address? { | ||
| // The index must be in the range [1 .. 2^45 - 1] | ||
| if index < 1 || index > (2 << 44) - 1 { | ||
| return nil | ||
| } | ||
| return Address(self.encodeWord(index) ^ self.invalidCodeWord(forChain: chain)) | ||
| } | ||
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| /// Returns true if the given address is valid, for the given chain code word. | ||
| access(all) | ||
| fun isValidAddress(_ address: Address, chain: Chain): Bool { | ||
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| let address = UInt64.fromBigEndianBytes(address.toBytes())! | ||
| var codeWord = self.invalidCodeWord(forChain: chain) ^ address | ||
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| if codeWord == 0 { | ||
| return false | ||
| } | ||
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| // Multiply the code word GF(2)-vector by the parity-check matrix | ||
| var parity: UInt64 = 0 | ||
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| for parityCheckMatrixColumn in self.parityCheckMatrixColumns { | ||
| if codeWord & 1 == 1 { | ||
| parity = parity ^ parityCheckMatrixColumn | ||
| } | ||
| codeWord = codeWord >> 1 | ||
| } | ||
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| return parity == 0 && codeWord == 0 | ||
| } | ||
| } |
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