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descriptors: disallow hybrid public keys
The descriptor documentation (doc/descriptors.md) and BIP380 explicitly require that hex-encoded public keys start with 02 or 03 (compressed) or 04 (uncompressed). However, the current parsing/inference code permit 06 and 07 (hybrid) encoding as well. Fix this.
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+21
-2
lines changed

3 files changed

+21
-2
lines changed

‎src/pubkey.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -191,6 +191,12 @@ class CPubKey
191191
return size() > 0;
192192
}
193193

194+
/** Check if a public key is a syntactically valid compressed or uncompressed key. */
195+
bool IsValidNonHybrid() const noexcept
196+
{
197+
return size() > 0 && (vch[0] == 0x02 || vch[0] == 0x03 || vch[0] == 0x04);
198+
}
199+
194200
//! fully validate whether this is a valid public key (more expensive than IsValid())
195201
bool IsFullyValid() const;
196202

‎src/script/descriptor.cpp

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1290,6 +1290,10 @@ std::unique_ptr<PubkeyProvider> ParsePubkeyInner(uint32_t key_exp_index, const S
12901290
if (IsHex(str)) {
12911291
std::vector<unsigned char> data = ParseHex(str);
12921292
CPubKey pubkey(data);
1293+
if (pubkey.IsValid() && !pubkey.IsValidNonHybrid()) {
1294+
error = "Hybrid public keys are not allowed";
1295+
return nullptr;
1296+
}
12931297
if (pubkey.IsFullyValid()) {
12941298
if (permit_uncompressed || pubkey.IsCompressed()) {
12951299
return std::make_unique<ConstPubkeyProvider>(key_exp_index, pubkey, false);
@@ -1448,7 +1452,7 @@ struct KeyParser {
14481452
{
14491453
assert(m_in);
14501454
CPubKey pubkey(begin, end);
1451-
if (pubkey.IsValid()) {
1455+
if (pubkey.IsValidNonHybrid()) {
14521456
Key key = m_keys.size();
14531457
m_keys.push_back(InferPubkey(pubkey, ParseScriptContext::P2WSH, *m_in));
14541458
return key;
@@ -1795,7 +1799,7 @@ std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptCo
17951799

17961800
if (txntype == TxoutType::PUBKEY && (ctx == ParseScriptContext::TOP || ctx == ParseScriptContext::P2SH || ctx == ParseScriptContext::P2WSH)) {
17971801
CPubKey pubkey(data[0]);
1798-
if (pubkey.IsValid()) {
1802+
if (pubkey.IsValidNonHybrid()) {
17991803
return std::make_unique<PKDescriptor>(InferPubkey(pubkey, ctx, provider));
18001804
}
18011805
}

‎src/test/descriptor_tests.cpp

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -409,6 +409,11 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
409409
CheckUnparsable("wsh(pk(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))", "wsh(pk(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))", "pk(): Uncompressed keys are not allowed"); // No uncompressed keys in witness
410410
CheckUnparsable("sh(wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))", "sh(wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))", "wpkh(): Uncompressed keys are not allowed"); // No uncompressed keys in witness
411411

412+
// Equivalent single-key hybrid is not allowed
413+
CheckUnparsable("", "combo(07a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", "combo(): Hybrid public keys are not allowed");
414+
CheckUnparsable("", "pk(0623542d61708e3fc48ba78fbe8fcc983ba94a520bc33f82b8e45e51dbc47af2726bcf181925eee1bdd868b109314f3ea92a6fc23d6b66057d3acfba04d6b08b58)", "pk(): Hybrid public keys are not allowed");
415+
CheckUnparsable("", "pkh(07a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", "pkh(): Hybrid public keys are not allowed");
416+
412417
// Some unconventional single-key constructions
413418
Check("sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", "sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"a9141857af51a5e516552b3086430fd8ce55f7c1a52487"}}, OutputType::LEGACY);
414419
Check("sh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", "sh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"a9141a31ad23bf49c247dd531a623c2ef57da3c400c587"}}, OutputType::LEGACY);
@@ -538,6 +543,10 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
538543
CheckUnparsable("tr(and_v(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "tr(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "tr(): key 'and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10))' is not valid");
539544
CheckUnparsable("raw(and_v(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "sh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "Miniscript expressions can only be used in wsh");
540545
CheckUnparsable("", "tr(034D2224bbbbbbbbbbcbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb40,{{{{{{{{{{{{{{{{{{{{{{multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008')", "'multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008'' is not a valid descriptor function");
546+
// No uncompressed keys allowed
547+
CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(049228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
548+
// No hybrid keys allowed
549+
CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(069228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
541550
// Insane at top level
542551
CheckUnparsable("wsh(and_b(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "wsh(and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)) is invalid");
543552
// Invalid sub

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