62 lines
2.1 KiB
Erlang
62 lines
2.1 KiB
Erlang
%%% File : ecu_crypto.erl
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%%% Author : Hans Svensson
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%%% Description :
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%%% Created : 13 Jan 2022 by Hans Svensson
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-module(ecu_crypto).
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-vsn("0.1.0").
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-export([private_to_short/2, public_to_short/2,
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eth_sign/2, eth_recover/2, eth_verify/3, eth_msg_hash/1,
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keccak256/1]).
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private_to_short(bitcoin, PrivateKey) ->
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public_to_short(bitcoin, aeu_ecdsa:private_to_public(secp256k1, PrivateKey));
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private_to_short(ethereum, <<PrivateKey:256>>) ->
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public_to_short(ethereum, ecu_secp256k1:scalar_mul_base(PrivateKey)).
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public_to_short(bitcoin, PubKey = <<_:33/bytes>>) ->
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crypto:hash(ripemd160, crypto:hash(sha256, PubKey));
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public_to_short(bitcoin, PubKey) ->
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crypto:hash(ripemd160, crypto:hash(sha256, ecu_secp256k1:compress(PubKey)));
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public_to_short(ethereum, PubKey) ->
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case PubKey of
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<<_:33/bytes>> -> public_to_short(ethereum, ecu_secp256k1:decompress(PubKey));
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<<4:8, X:256, Y:256>> -> public_to_short(ethereum, {X, Y});
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{X, Y} ->
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<<_:12/bytes, ShortPub:20/bytes>> = keccak256(<<X:256, Y:256>>),
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ShortPub
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end.
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eth_sign(Msg, PrivateKey = <<_:32/bytes>>) ->
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{BaseSig, YVal} = ecu_ecdsa:sign_secp256k1(eth_msg_hash(Msg), PrivateKey),
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V = if YVal rem 2 == 0 -> 27;
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true -> 28
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end,
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<<V:8, BaseSig/bytes>>.
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eth_recover(Msg, Sig = <<_:65/bytes>>) ->
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MsgHash = eth_msg_hash(Msg),
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<<E:256>> = MsgHash,
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<<V:8, R:256, S:256>> = Sig,
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Z = E rem ecu_secp256k1:n(),
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RInv = ecu_secp256k1:s_inv(R),
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Rd = ecu_secp256k1:decompress(<<(V - 27 + 2):8, R:256>>),
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[P1, P2] =
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ecu_misc:pcomp(
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[fun() -> ecu_secp256k1:scalar_mul(ecu_secp256k1:s_mul(RInv, S), Rd) end,
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fun() -> ecu_secp256k1:scalar_mul_base(ecu_secp256k1:s_mul(RInv,Z)) end]),
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{X, Y} = ecu_secp256k1:p_add(P1, ecu_secp256k1:p_neg(P2)),
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<<_:12/bytes, RPub:20/bytes>> = keccak256(<<X:256, Y:256>>),
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RPub.
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eth_verify(Msg, PublicKey, Sig) ->
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PublicKey == eth_recover(Msg, Sig).
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eth_msg_hash(Msg0) ->
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Msg = ["\x19Ethereum Signed Message:\n", integer_to_list(byte_size(Msg0)), Msg0],
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keccak256(iolist_to_binary(Msg)).
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keccak256(Bin) ->
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sha3:hash(256, Bin).
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