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Add blech32 python implementation with diff annotation with segwit_ad…

`…dr.py`
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instagibbs authored and stevenroose committed Mar 1, 2019
1 parent 17a22f1 commit 9cb2fa051fcbe0fe66f15e6b88d224d1935376f4
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1. +106 −0 test/functional/test_framework/liquid_addr.py
 @@ -0,0 +1,106 @@ #!/usr/bin/env python3 # Copyright (c) 2017 Pieter Wuille # Distributed under the MIT software license, see the accompanying # file COPYING or http://www.opensource.org/licenses/mit-license.php. """Reference implementation for Blech32 and segwit addresses.""" CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l" def blech32_polymod(values): """Internal function that computes the blech32 checksum.""" generator = [0x7d52fba40bd886, 0x5e8dbf1a03950c, 0x1c3a3c74072a18, 0x385d72fa0e5139, 0x7093e5a608865b] # new generators, 7 bytes chk = 1 for value in values: top = chk >> 55 # 25->55 chk = ((chk & 0x7fffffffffffff) << 5) ^^ value # 0x1ffffff->0x7fffffffffffff for i in range(5): chk ^= generator[i] if ((top >> i) & 1) else 0 return chk def blech32_hrp_expand(hrp): """Expand the HRP into values for checksum computation.""" return [ord(x) >> 5 for x in hrp] + [0] + [ord(x) & 31 for x in hrp] def blech32_verify_checksum(hrp, data): """Verify a checksum given HRP and converted data characters.""" return blech32_polymod(blech32_hrp_expand(hrp) + data) == 1 def blech32_create_checksum(hrp, data): """Compute the checksum values given HRP and data.""" values = blech32_hrp_expand(hrp) + data polymod = blech32_polymod(values + [0]*12) ^^ 1 # 6->12 return [(polymod >> 5 * (11 - i)) & 31 for i in range(12)] # ^ 5 ^ 6 def blech32_encode(hrp, data): """Compute a blech32 string given HRP and data values.""" combined = data + blech32_create_checksum(hrp, data) return hrp + '1' + ''.join([CHARSET[d] for d in combined]) def blech32_decode(bech): """Validate a blech32 string, and determine HRP and data.""" if ((any(ord(x) < 33 or ord(x) > 126 for x in bech)) or (bech.lower() != bech and bech.upper() != bech)): return (None, None) bech = bech.lower() pos = bech.rfind('1') if pos < 1 or pos + 13 > len(bech) or len(bech) > 1000: # 7->13 90->1000 return (None, None) if not all(x in CHARSET for x in bech[pos+1:]): return (None, None) hrp = bech[:pos] data = [CHARSET.find(x) for x in bech[pos+1:]] if not blech32_verify_checksum(hrp, data): return (None, None) return (hrp, data[:-12]) # 6->12 def convertbits(data, frombits, tobits, pad=True): """General power-of-2 base conversion.""" acc = 0 bits = 0 ret = [] maxv = (1 << tobits) - 1 max_acc = (1 << (frombits + tobits - 1)) - 1 for value in data: if value < 0 or (value >> frombits): return None acc = ((acc << frombits) | value) & max_acc bits += frombits while bits >= tobits: bits -= tobits ret.append((acc >> bits) & maxv) if pad: if bits: ret.append((acc << (tobits - bits)) & maxv) elif bits >= frombits or ((acc << (tobits - bits)) & maxv): return None return ret def decode(hrp, addr): """Decode a segwit address.""" hrpgot, data = blech32_decode(addr) if hrpgot != hrp: return (None, None) decoded = convertbits(data[1:], 5, 8, False) if decoded is None or len(decoded) < 2 or len(decoded) > 40: return (None, None) if data[0] > 16: return (None, None) if data[0] == 0 and len(decoded) != 20 and len(decoded) != 32: return (None, None) return (data[0], decoded) def encode(hrp, witver, witprog): """Encode a segwit address.""" ret = blech32_encode(hrp, [witver] + convertbits(witprog, 8, 5)) if decode(hrp, ret) == (None, None): return None return ret

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