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January 25, 2018 12:33
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| -module(tpecdsa). | |
| -export([generate_priv/0,minify/1,calc_pub/2,sign/2,verify/3]). | |
| -export([secp256k1_ecdsa_sign/4, | |
| secp256k1_ecdsa_verify/3, | |
| secp256k1_ec_pubkey_create/2, | |
| secp256k1_ec_pubkey_create/1 | |
| ]). | |
| -ifdef(TEST). | |
| -include_lib("eunit/include/eunit.hrl"). | |
| -endif. | |
| generate_priv() -> | |
| generate_priv(10). | |
| generate_priv(0) -> | |
| throw('cant_generate'); | |
| generate_priv(N) -> | |
| case crypto:generate_key(ecdh, crypto:ec_curve(secp256k1)) of | |
| {_,<<255,255,255,255,255,255,255,255,255,255,_/binary>>} -> | |
| %avoid priv keys with leading ones | |
| generate_priv(N-1); | |
| {_,<<Private:32/binary>>} -> | |
| Private; | |
| _ -> | |
| %avoid priv keys with leading zeros | |
| generate_priv(N-1) | |
| end. | |
| minify(XPub) -> | |
| case XPub of | |
| <<Gxp:8/integer,Gy:32/binary,_:31/binary>> when Gxp==2 orelse Gxp==3-> | |
| <<Gxp:8/integer,Gy:32/binary>>; | |
| <<4,Gy:32/binary,_:31/binary,Gxx:8/integer>> -> | |
| Gxp=if Gxx rem 2 == 1 -> 3; | |
| true -> 2 | |
| end, | |
| <<Gxp:8/integer,Gy:32/binary>> | |
| end. | |
| calc_pub(Priv, false) -> %full X | |
| {XPub, _XPrivi} = crypto:generate_key(ecdh, crypto:ec_curve(secp256k1), Priv), | |
| %it's ok. regenerated priv can be less tnan 32 bytes, is it with leading zeros | |
| %BigInt=binary:decode_unsigned(XPrivi), | |
| %Priv= <<BigInt:256/integer>>, | |
| XPub; | |
| calc_pub(Priv, true) -> %compact X | |
| {XPub, _XPrivi} = crypto:generate_key(ecdh, crypto:ec_curve(secp256k1), Priv), | |
| %it's ok. regenerated priv can be less tnan 32 bytes, is it with leading zeros | |
| %BigInt=binary:decode_unsigned(XPrivi), | |
| %Priv= <<BigInt:256/integer>>, | |
| tpecdsa:minify(XPub). | |
| sign(Message,PrivKey) -> | |
| crypto:sign(ecdsa, sha256, Message, [PrivKey, crypto:ec_curve(secp256k1)]). | |
| verify(Message,Public,Sig) -> | |
| R=crypto:verify(ecdsa, sha256, Message, Sig, [Public, crypto:ec_curve(secp256k1)]), | |
| if R -> correct; | |
| true -> incorrect | |
| end. | |
| secp256k1_ecdsa_sign(Msg32, SecKey, _Nonce, _NonceData) -> | |
| sign(Msg32,SecKey). | |
| secp256k1_ecdsa_verify(Msg32, Sig, Pubkey) -> | |
| verify(Msg32, Pubkey, Sig). | |
| secp256k1_ec_pubkey_create(SecKey) -> %use mini keys by default | |
| calc_pub(SecKey, true). | |
| secp256k1_ec_pubkey_create(SecKey, Compressed) -> | |
| calc_pub(SecKey, Compressed). | |
| -ifdef(TEST). | |
| sign_test() -> | |
| SecKey = <<128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128>>, | |
| Msg32 = <<"Hello">>, | |
| << _/binary >> = Sig = secp256k1_ecdsa_sign(Msg32, SecKey, default, <<>>), | |
| ?assertEqual(correct, secp256k1_ecdsa_verify(Msg32, Sig, secp256k1_ec_pubkey_create(SecKey, false))), | |
| ?assertEqual(correct, secp256k1_ecdsa_verify(Msg32, Sig, secp256k1_ec_pubkey_create(SecKey, true))), | |
| ?assertEqual(incorrect, secp256k1_ecdsa_verify(<<1,Msg32/binary>>, Sig, secp256k1_ec_pubkey_create(SecKey, false))). | |
| -endif. | |
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