Merge #15368: Descriptor checksums

fd637be8d21a606e98c037b40b268c4a1fae2244 Add checksums to descriptors.md (Pieter Wuille)
be62903c417293f6217e124669e62fd2172a18f1 Make descriptor checksums mandatory in deriveaddresses and importmulti (Pieter Wuille)
b52cb6368869c9f6dd2cd8f309b3000de514d439 Add getdescriptorinfo to compute checksum (Pieter Wuille)
3b40bff9880e9ae2817136b7d14989afccfc1937 Descriptor checksum (Pieter Wuille)

Pull request description:

  This adds support for a descriptor-specific 8-character checksum.

  Descriptors may optionally be suffixed with a `#` plus these 8 checksum characters. Any descriptor that contains a `#` at the end must be followed by a valid checksum. If the `#` is missing entirely, it is valid without checksum.

  All RPCs are updated to report descriptors that include the checksum. On input, they are optional except in `deriveaddress` and `importmulti`, which require descriptors which include a checksum.

  A new RPC is also added to analyse descriptors (`getdescriptorinfo`), which can be used to compute the checksum for a descriptor without.

Tree-SHA512: a8294b09155eb6c67fbc178b5e2d3fbc0e9bec8b6de57a13f8835550d51c2cb32a428b3c9a188ded42b454d594e9305edbd4797906b755de77a8f33c79165f6b

11 files changed, 357 insertions, 52 deletions

diff --git a/doc/descriptors.md b/doc/descriptors.md
index de4d4e574f..5dbcd95e1d 100644
--- a/doc/descriptors.md
+++ b/doc/descriptors.md
@@ -39,7 +39,7 @@ Output descriptors currently support:
 
 ## Reference
 
-Descriptors consist of several types of expressions. The top level expression is always a `SCRIPT`.
+Descriptors consist of several types of expressions. The top level expression is either a `SCRIPT`, or `SCRIPT#CHECKSUM` where `CHECKSUM` is an 8-character alphanumeric descriptor checksum.
 
 `SCRIPT` expressions:
 - `sh(SCRIPT)` (top level only): P2SH embed the argument.
@@ -169,3 +169,20 @@ existing Bitcoin Core wallets, a convenience function `combo` is
 provided, which takes as input a public key, and describes a set of P2PK,
 P2PKH, P2WPKH, and P2SH-P2WPH scripts for that key. In case the key is
 uncompressed, the set only includes P2PK and P2PKH scripts.
+
+### Checksums
+
+Descriptors can optionally be suffixed with a checksum to protect against
+typos or copy-paste errors.
+
+These checksums consist of 8 alphanumeric characters. As long as errors are
+restricted to substituting characters in `0123456789()[],'/*abcdefgh@:$%{}`
+for others in that set and changes in letter case, up to 4 errors will always
+be detected in descriptors up to 501 characters, and up to 3 errors in longer
+ones. For larger numbers of errors, or other types of errors, there is a
+roughly 1 in a trillion chance of not detecting the errors.
+
+All RPCs in Bitcoin Core will include the checksum in their output. Only
+certain RPCs require checksums on input, including `deriveaddress` and
+`importmulti`. The checksum for a descriptor without one can be computed
+using the `getdescriptorinfo` RPC.
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 784adfa969..999a307e2b 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -143,6 +143,46 @@ static UniValue createmultisig(const JSONRPCRequest& request)
     return result;
 }
 
+UniValue getdescriptorinfo(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 1) {
+        throw std::runtime_error(
+            RPCHelpMan{"getdescriptorinfo",
+            {"\nAnalyses a descriptor.\n"},
+            {
+                {"descriptor", RPCArg::Type::STR, RPCArg::Optional::NO, "The descriptor."},
+            },
+            RPCResult{
+            "{\n"
+            "  \"descriptor\" : \"desc\",         (string) The descriptor in canonical form, without private keys\n"
+            "  \"isrange\" : true|false,        (boolean) Whether the descriptor is ranged\n"
+            "  \"issolvable\" : true|false,     (boolean) Whether the descriptor is solvable\n"
+            "  \"hasprivatekeys\" : true|false, (boolean) Whether the input descriptor contained at least one private key\n"
+            "}\n"
+            },
+            RPCExamples{
+                "Analyse a descriptor\n" +
+                HelpExampleCli("getdescriptorinfo", "\"wpkh([d34db33f/84h/0h/0h]0279be667ef9dcbbac55a06295Ce870b07029Bfcdb2dce28d959f2815b16f81798)\"")
+            }}.ToString()
+        );
+    }
+
+    RPCTypeCheck(request.params, {UniValue::VSTR});
+
+    FlatSigningProvider provider;
+    auto desc = Parse(request.params[0].get_str(), provider);
+    if (!desc) {
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Invalid descriptor"));
+    }
+
+    UniValue result(UniValue::VOBJ);
+    result.pushKV("descriptor", desc->ToString());
+    result.pushKV("isrange", desc->IsRange());
+    result.pushKV("issolvable", desc->IsSolvable());
+    result.pushKV("hasprivatekeys", provider.keys.size() > 0);
+    return result;
+}
+
 UniValue deriveaddresses(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.empty() || request.params.size() > 3) {
@@ -167,7 +207,7 @@ UniValue deriveaddresses(const JSONRPCRequest& request)
             },
             RPCExamples{
                 "First three native segwit receive addresses\n" +
-                HelpExampleCli("deriveaddresses", "\"wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)\" 0 2")
+                HelpExampleCli("deriveaddresses", "\"wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)#trd0mf0l\" 0 2")
             }}.ToString()
         );
     }
@@ -193,7 +233,7 @@ UniValue deriveaddresses(const JSONRPCRequest& request)
     }
 
     FlatSigningProvider provider;
-    auto desc = Parse(desc_str, provider);
+    auto desc = Parse(desc_str, provider, /* require_checksum = */ true);
     if (!desc) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Invalid descriptor"));
     }
@@ -564,6 +604,7 @@ static const CRPCCommand commands[] =
     { "util",               "validateaddress",        &validateaddress,        {"address"} },
     { "util",               "createmultisig",         &createmultisig,         {"nrequired","keys","address_type"} },
     { "util",               "deriveaddresses",        &deriveaddresses,        {"descriptor", "begin", "end"} },
+    { "util",               "getdescriptorinfo",      &getdescriptorinfo,      {"descriptor"} },
     { "util",               "verifymessage",          &verifymessage,          {"address","signature","message"} },
     { "util",               "signmessagewithprivkey", &signmessagewithprivkey, {"privkey","message"} },
 
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index 532a8028a2..43448d7222 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -21,6 +21,125 @@
 namespace {
 
 ////////////////////////////////////////////////////////////////////////////
+// Checksum                                                               //
+////////////////////////////////////////////////////////////////////////////
+
+// This section implements a checksum algorithm for descriptors with the
+// following properties:
+// * Mistakes in a descriptor string are measured in "symbol errors". The higher
+//   the number of symbol errors, the harder it is to detect:
+//   * An error substituting a character from 0123456789()[],'/*abcdefgh@:$%{} for
+//     another in that set always counts as 1 symbol error.
+//     * Note that hex encoded keys are covered by these characters. Xprvs and
+//       xpubs use other characters too, but already have their own checksum
+//       mechanism.
+//     * Function names like "multi()" use other characters, but mistakes in
+//       these would generally result in an unparseable descriptor.
+//   * A case error always counts as 1 symbol error.
+//   * Any other 1 character substitution error counts as 1 or 2 symbol errors.
+// * Any 1 symbol error is always detected.
+// * Any 2 or 3 symbol error in a descriptor of up to 49154 characters is always detected.
+// * Any 4 symbol error in a descriptor of up to 507 characters is always detected.
+// * Any 5 symbol error in a descriptor of up to 77 characters is always detected.
+// * Is optimized to minimize the chance a 5 symbol error in a descriptor up to 387 characters is undetected
+// * Random errors have a chance of 1 in 2**40 of being undetected.
+//
+// These properties are achieved by expanding every group of 3 (non checksum) characters into
+// 4 GF(32) symbols, over which a cyclic code is defined.
+
+/*
+ * Interprets c as 8 groups of 5 bits which are the coefficients of a degree 8 polynomial over GF(32),
+ * multiplies that polynomial by x, computes its remainder modulo a generator, and adds the constant term val.
+ *
+ * This generator is G(x) = x^8 + {30}x^7 + {23}x^6 + {15}x^5 + {14}x^4 + {10}x^3 + {6}x^2 + {12}x + {9}.
+ * It is chosen to define an cyclic error detecting code which is selected by:
+ * - Starting from all BCH codes over GF(32) of degree 8 and below, which by construction guarantee detecting
+ *   3 errors in windows up to 19000 symbols.
+ * - Taking all those generators, and for degree 7 ones, extend them to degree 8 by adding all degree-1 factors.
+ * - Selecting just the set of generators that guarantee detecting 4 errors in a window of length 512.
+ * - Selecting one of those with best worst-case behavior for 5 errors in windows of length up to 512.
+ *
+ * The generator and the constants to implement it can be verified using this Sage code:
+ *   B = GF(2) # Binary field
+ *   BP.<b> = B[] # Polynomials over the binary field
+ *   F_mod = b**5 + b**3 + 1
+ *   F.<f> = GF(32, modulus=F_mod, repr='int') # GF(32) definition
+ *   FP.<x> = F[] # Polynomials over GF(32)
+ *   E_mod = x**3 + x + F.fetch_int(8)
+ *   E.<e> = F.extension(E_mod) # Extension field definition
+ *   alpha = e**2743 # Choice of an element in extension field
+ *   for p in divisors(E.order() - 1): # Verify alpha has order 32767.
+ *       assert((alpha**p == 1) == (p % 32767 == 0))
+ *   G = lcm([(alpha**i).minpoly() for i in [1056,1057,1058]] + [x + 1])
+ *   print(G) # Print out the generator
+ *   for i in [1,2,4,8,16]: # Print out {1,2,4,8,16}*(G mod x^8), packed in hex integers.
+ *       v = 0
+ *       for coef in reversed((F.fetch_int(i)*(G % x**8)).coefficients(sparse=True)):
+ *           v = v*32 + coef.integer_representation()
+ *       print("0x%x" % v)
+ */
+uint64_t PolyMod(uint64_t c, int val)
+{
+    uint8_t c0 = c >> 35;
+    c = ((c & 0x7ffffffff) << 5) ^ val;
+    if (c0 & 1) c ^= 0xf5dee51989;
+    if (c0 & 2) c ^= 0xa9fdca3312;
+    if (c0 & 4) c ^= 0x1bab10e32d;
+    if (c0 & 8) c ^= 0x3706b1677a;
+    if (c0 & 16) c ^= 0x644d626ffd;
+    return c;
+}
+
+std::string DescriptorChecksum(const Span<const char>& span)
+{
+    /** A character set designed such that:
+     *  - The most common 'unprotected' descriptor characters (hex, keypaths) are in the first group of 32.
+     *  - Case errors cause an offset that's a multiple of 32.
+     *  - As many alphabetic characters are in the same group (while following the above restrictions).
+     *
+     * If p(x) gives the position of a character c in this character set, every group of 3 characters
+     * (a,b,c) is encoded as the 4 symbols (p(a) & 31, p(b) & 31, p(c) & 31, (p(a) / 32) + 3 * (p(b) / 32) + 9 * (p(c) / 32).
+     * This means that changes that only affect the lower 5 bits of the position, or only the higher 2 bits, will just
+     * affect a single symbol.
+     *
+     * As a result, within-group-of-32 errors count as 1 symbol, as do cross-group errors that don't affect
+     * the position within the groups.
+     */
+    static std::string INPUT_CHARSET =
+        "0123456789()[],'/*abcdefgh@:$%{}"
+        "IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~"
+        "ijklmnopqrstuvwxyzABCDEFGH`#\"\\ ";
+
+    /** The character set for the checksum itself (same as bech32). */
+    static std::string CHECKSUM_CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
+
+    uint64_t c = 1;
+    int cls = 0;
+    int clscount = 0;
+    for (auto ch : span) {
+        auto pos = INPUT_CHARSET.find(ch);
+        if (pos == std::string::npos) return "";
+        c = PolyMod(c, pos & 31); // Emit a symbol for the position inside the group, for every character.
+        cls = cls * 3 + (pos >> 5); // Accumulate the group numbers
+        if (++clscount == 3) {
+            // Emit an extra symbol representing the group numbers, for every 3 characters.
+            c = PolyMod(c, cls);
+            cls = 0;
+            clscount = 0;
+        }
+    }
+    if (clscount > 0) c = PolyMod(c, cls);
+    for (int j = 0; j < 8; ++j) c = PolyMod(c, 0); // Shift further to determine the checksum.
+    c ^= 1; // Prevent appending zeroes from not affecting the checksum.
+
+    std::string ret(8, ' ');
+    for (int j = 0; j < 8; ++j) ret[j] = CHECKSUM_CHARSET[(c >> (5 * (7 - j))) & 31];
+    return ret;
+}
+
+std::string AddChecksum(const std::string& str) { return str + "#" + DescriptorChecksum(MakeSpan(str)); }
+
+////////////////////////////////////////////////////////////////////////////
 // Internal representation                                                //
 ////////////////////////////////////////////////////////////////////////////
 
@@ -273,10 +392,15 @@ public:
     {
         std::string ret;
         ToStringHelper(nullptr, ret, false);
-        return ret;
+        return AddChecksum(ret);
     }
 
-    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final { return ToStringHelper(&arg, out, true); }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final
+    {
+        bool ret = ToStringHelper(&arg, out, true);
+        out = AddChecksum(out);
+        return ret;
+    }
 
     bool ExpandHelper(int pos, const SigningProvider& arg, Span<const unsigned char>* cache_read, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache_write) const
     {
@@ -751,11 +875,25 @@ std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptCo
     return MakeUnique<RawDescriptor>(script);
 }
 
+
 } // namespace
 
-std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out)
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, bool require_checksum)
 {
     Span<const char> sp(descriptor.data(), descriptor.size());
+
+    // Checksum checks
+    auto check_split = Split(sp, '#');
+    if (check_split.size() > 2) return nullptr; // Multiple '#' symbols
+    if (check_split.size() == 1 && require_checksum) return nullptr; // Missing checksum
+    if (check_split.size() == 2) {
+        if (check_split[1].size() != 8) return nullptr; // Unexpected length for checksum
+        auto checksum = DescriptorChecksum(check_split[0]);
+        if (checksum.empty()) return nullptr; // Invalid characters in payload
+        if (!std::equal(checksum.begin(), checksum.end(), check_split[1].begin())) return nullptr; // Checksum mismatch
+    }
+    sp = check_split[0];
+
     auto ret = ParseScript(sp, ParseScriptContext::TOP, out);
     if (sp.size() == 0 && ret) return std::unique_ptr<Descriptor>(std::move(ret));
     return nullptr;
diff --git a/src/script/descriptor.h b/src/script/descriptor.h
index 44f0efca03..907a102284 100644
--- a/src/script/descriptor.h
+++ b/src/script/descriptor.h
@@ -62,8 +62,15 @@ struct Descriptor {
     virtual bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
 };
 
-/** Parse a descriptor string. Included private keys are put in out. Returns nullptr if parsing fails. */
-std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out);
+/** Parse a descriptor string. Included private keys are put in out.
+ *
+ * If the descriptor has a checksum, it must be valid. If require_checksum
+ * is set, the checksum is mandatory - otherwise it is optional.
+ *
+ * If a parse error occurs, or the checksum is missing/invalid, or anything
+ * else is wrong, nullptr is returned.
+ */
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, bool require_checksum = false);
 
 /** Find a descriptor for the specified script, using information from provider where possible.
  *
diff --git a/src/test/descriptor_tests.cpp b/src/test/descriptor_tests.cpp
index 8da8cfc00c..ff2b8d4fc9 100644
--- a/src/test/descriptor_tests.cpp
+++ b/src/test/descriptor_tests.cpp
@@ -18,8 +18,8 @@ void CheckUnparsable(const std::string& prv, const std::string& pub)
     FlatSigningProvider keys_priv, keys_pub;
     auto parse_priv = Parse(prv, keys_priv);
     auto parse_pub = Parse(pub, keys_pub);
-    BOOST_CHECK(!parse_priv);
-    BOOST_CHECK(!parse_pub);
+    BOOST_CHECK_MESSAGE(!parse_priv, prv);
+    BOOST_CHECK_MESSAGE(!parse_pub, pub);
 }
 
 constexpr int DEFAULT = 0;
@@ -28,6 +28,18 @@ constexpr int HARDENED = 2; // Derivation needs access to private keys
 constexpr int UNSOLVABLE = 4; // This descriptor is not expected to be solvable
 constexpr int SIGNABLE = 8; // We can sign with this descriptor (this is not true when actual BIP32 derivation is used, as that's not integrated in our signing code)
 
+/** Compare two descriptors. If only one of them has a checksum, the checksum is ignored. */
+bool EqualDescriptor(std::string a, std::string b)
+{
+    bool a_check = (a.size() > 9 && a[a.size() - 9] == '#');
+    bool b_check = (b.size() > 9 && b[b.size() - 9] == '#');
+    if (a_check != b_check) {
+        if (a_check) a = a.substr(0, a.size() - 9);
+        if (b_check) b = b.substr(0, b.size() - 9);
+    }
+    return a == b;
+}
+
 std::string MaybeUseHInsteadOfApostrophy(std::string ret)
 {
     if (InsecureRandBool()) {
@@ -35,6 +47,7 @@ std::string MaybeUseHInsteadOfApostrophy(std::string ret)
             auto it = ret.find("'");
             if (it != std::string::npos) {
                 ret[it] = 'h';
+                if (ret.size() > 9 && ret[ret.size() - 9] == '#') ret = ret.substr(0, ret.size() - 9); // Changing apostrophe to h breaks the checksum
             } else {
                 break;
             }
@@ -63,16 +76,16 @@ void Check(const std::string& prv, const std::string& pub, int flags, const std:
     // Check that both versions serialize back to the public version.
     std::string pub1 = parse_priv->ToString();
     std::string pub2 = parse_pub->ToString();
-    BOOST_CHECK_EQUAL(pub, pub1);
-    BOOST_CHECK_EQUAL(pub, pub2);
+    BOOST_CHECK(EqualDescriptor(pub, pub1));
+    BOOST_CHECK(EqualDescriptor(pub, pub2));
 
     // Check that both can be serialized with private key back to the private version, but not without private key.
     std::string prv1;
     BOOST_CHECK(parse_priv->ToPrivateString(keys_priv, prv1));
-    BOOST_CHECK_EQUAL(prv, prv1);
+    BOOST_CHECK(EqualDescriptor(prv, prv1));
     BOOST_CHECK(!parse_priv->ToPrivateString(keys_pub, prv1));
     BOOST_CHECK(parse_pub->ToPrivateString(keys_priv, prv1));
-    BOOST_CHECK_EQUAL(prv, prv1);
+    BOOST_CHECK(EqualDescriptor(prv, prv1));
     BOOST_CHECK(!parse_pub->ToPrivateString(keys_pub, prv1));
 
     // Check whether IsRange on both returns the expected result
@@ -210,6 +223,15 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
     CheckUnparsable("wsh(sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "wsh(sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2SH inside P2WSH
     CheckUnparsable("sh(sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "sh(sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2SH inside P2SH
     CheckUnparsable("wsh(wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "wsh(wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2WSH inside P2WSH
+
+    // Checksums
+    Check("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#ggrsrxfy", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#tjg09x5t", DEFAULT, {{"a91445a9a622a8b0a1269944be477640eedc447bbd8487"}}, {{0x8000006FUL,222},{0}});
+    Check("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))", DEFAULT, {{"a91445a9a622a8b0a1269944be477640eedc447bbd8487"}}, {{0x8000006FUL,222},{0}});
+    CheckUnparsable("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#"); // Empty checksum
+    CheckUnparsable("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#ggrsrxfyq", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#tjg09x5tq"); // Too long checksum
+    CheckUnparsable("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#ggrsrxf", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#tjg09x5"); // Too short checksum
+    CheckUnparsable("sh(multi(3,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#ggrsrxfy", "sh(multi(3,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#tjg09x5t"); // Error in payload
+    CheckUnparsable("sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))#ggssrxfy", "sh(multi(2,[00000000/111'/222]xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))#tjq09x4t"); // Error in checksum
 }
 
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 930274f8a1..66a52c1270 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1117,7 +1117,7 @@ static UniValue ProcessImportDescriptor(ImportData& import_data, std::map<CKeyID
 
     const std::string& descriptor = data["desc"].get_str();
     FlatSigningProvider keys;
-    auto parsed_desc = Parse(descriptor, keys);
+    auto parsed_desc = Parse(descriptor, keys, /* require_checksum = */ true);
     if (!parsed_desc) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Descriptor is invalid");
     }
diff --git a/test/functional/rpc_deriveaddresses.py b/test/functional/rpc_deriveaddresses.py
index 2cc5bc974b..c8b58cfc74 100755
--- a/test/functional/rpc_deriveaddresses.py
+++ b/test/functional/rpc_deriveaddresses.py
@@ -4,6 +4,7 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the deriveaddresses rpc call."""
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.descriptors import descsum_create
 from test_framework.util import assert_equal, assert_raises_rpc_error
 
 class DeriveaddressesTest(BitcoinTestFramework):
@@ -14,36 +15,37 @@ class DeriveaddressesTest(BitcoinTestFramework):
     def run_test(self):
         assert_raises_rpc_error(-5, "Invalid descriptor", self.nodes[0].deriveaddresses, "a")
 
-        descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"
+        descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)#t6wfjs64"
         address = "bcrt1qjqmxmkpmxt80xz4y3746zgt0q3u3ferr34acd5"
-
         assert_equal(self.nodes[0].deriveaddresses(descriptor), [address])
 
-        descriptor_pubkey = "wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0)"
-        address = "bcrt1qjqmxmkpmxt80xz4y3746zgt0q3u3ferr34acd5"
+        descriptor = descriptor[:-9]
+        assert_raises_rpc_error(-5, "Invalid descriptor", self.nodes[0].deriveaddresses, descriptor)
 
+        descriptor_pubkey = "wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0)#s9ga3alw"
+        address = "bcrt1qjqmxmkpmxt80xz4y3746zgt0q3u3ferr34acd5"
         assert_equal(self.nodes[0].deriveaddresses(descriptor_pubkey), [address])
 
-        ranged_descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"
+        ranged_descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)#kft60nuy"
         assert_equal(self.nodes[0].deriveaddresses(ranged_descriptor, 0, 2), [address, "bcrt1qhku5rq7jz8ulufe2y6fkcpnlvpsta7rq4442dy", "bcrt1qpgptk2gvshyl0s9lqshsmx932l9ccsv265tvaq"])
 
-        assert_raises_rpc_error(-8, "Range should not be specified for an un-ranged descriptor", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)", 0, 2)
+        assert_raises_rpc_error(-8, "Range should not be specified for an un-ranged descriptor", self.nodes[0].deriveaddresses, descsum_create("wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"), 0, 2)
 
-        assert_raises_rpc_error(-8, "Range must be specified for a ranged descriptor", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)")
+        assert_raises_rpc_error(-8, "Range must be specified for a ranged descriptor", self.nodes[0].deriveaddresses, descsum_create("wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"))
 
-        assert_raises_rpc_error(-8, "Missing range end parameter", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", 0)
+        assert_raises_rpc_error(-8, "Missing range end parameter", self.nodes[0].deriveaddresses, descsum_create("wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"), 0)
 
-        assert_raises_rpc_error(-8, "Range end should be equal to or greater than begin", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", 2, 0)
+        assert_raises_rpc_error(-8, "Range end should be equal to or greater than begin", self.nodes[0].deriveaddresses, descsum_create("wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"), 2, 0)
 
-        assert_raises_rpc_error(-8, "Range should be greater or equal than 0", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", -1, 0)
+        assert_raises_rpc_error(-8, "Range should be greater or equal than 0", self.nodes[0].deriveaddresses, descsum_create("wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"), -1, 0)
 
-        combo_descriptor = "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"
+        combo_descriptor = descsum_create("combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)")
         assert_equal(self.nodes[0].deriveaddresses(combo_descriptor), ["mtfUoUax9L4tzXARpw1oTGxWyoogp52KhJ", "mtfUoUax9L4tzXARpw1oTGxWyoogp52KhJ", address, "2NDvEwGfpEqJWfybzpKPHF2XH3jwoQV3D7x"])
 
-        hardened_without_privkey_descriptor = "wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1'/1/0)"
+        hardened_without_privkey_descriptor = descsum_create("wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1'/1/0)")
         assert_raises_rpc_error(-5, "Cannot derive script without private keys", self.nodes[0].deriveaddresses, hardened_without_privkey_descriptor)
 
-        bare_multisig_descriptor = "multi(1, tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0, tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/1)"
+        bare_multisig_descriptor = descsum_create("multi(1,tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0,tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/1)")
         assert_raises_rpc_error(-5, "Descriptor does not have a corresponding address", self.nodes[0].deriveaddresses, bare_multisig_descriptor)
 
 if __name__ == '__main__':
diff --git a/test/functional/rpc_scantxoutset.py b/test/functional/rpc_scantxoutset.py
index 11b4db6ec5..29074c6af3 100755
--- a/test/functional/rpc_scantxoutset.py
+++ b/test/functional/rpc_scantxoutset.py
@@ -97,9 +97,9 @@ class ScantxoutsetTest(BitcoinTestFramework):
         assert_equal(self.nodes[0].scantxoutset("start", [ {"desc": "combo(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/*)", "range": 1500}])['total_amount'], Decimal("28.672"))
 
         # Test the reported descriptors for a few matches
-        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ {"desc": "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/0h/0'/*)", "range": 1499}])), ["pkh([0c5f9a1e/0'/0'/0]026dbd8b2315f296d36e6b6920b1579ca75569464875c7ebe869b536a7d9503c8c)", "pkh([0c5f9a1e/0'/0'/1]033e6f25d76c00bedb3a8993c7d5739ee806397f0529b1b31dda31ef890f19a60c)"])
-        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"])), ["pkh([0c5f9a1e/1/1/0]03e1c5b6e650966971d7e71ef2674f80222752740fc1dfd63bbbd220d2da9bd0fb)"])
-        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ {"desc": "combo(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/*)", "range": 1500}])), ['pkh([0c5f9a1e/1/1/0]03e1c5b6e650966971d7e71ef2674f80222752740fc1dfd63bbbd220d2da9bd0fb)', 'pkh([0c5f9a1e/1/1/1500]03832901c250025da2aebae2bfb38d5c703a57ab66ad477f9c578bfbcd78abca6f)', 'pkh([0c5f9a1e/1/1/1]030d820fc9e8211c4169be8530efbc632775d8286167afd178caaf1089b77daba7)'])
+        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ {"desc": "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/0h/0'/*)", "range": 1499}])), ["pkh([0c5f9a1e/0'/0'/0]026dbd8b2315f296d36e6b6920b1579ca75569464875c7ebe869b536a7d9503c8c)#dzxw429x", "pkh([0c5f9a1e/0'/0'/1]033e6f25d76c00bedb3a8993c7d5739ee806397f0529b1b31dda31ef890f19a60c)#43rvceed"])
+        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"])), ["pkh([0c5f9a1e/1/1/0]03e1c5b6e650966971d7e71ef2674f80222752740fc1dfd63bbbd220d2da9bd0fb)#cxmct4w8"])
+        assert_equal(descriptors(self.nodes[0].scantxoutset("start", [ {"desc": "combo(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/*)", "range": 1500}])), ['pkh([0c5f9a1e/1/1/0]03e1c5b6e650966971d7e71ef2674f80222752740fc1dfd63bbbd220d2da9bd0fb)#cxmct4w8', 'pkh([0c5f9a1e/1/1/1500]03832901c250025da2aebae2bfb38d5c703a57ab66ad477f9c578bfbcd78abca6f)#vchwd07g', 'pkh([0c5f9a1e/1/1/1]030d820fc9e8211c4169be8530efbc632775d8286167afd178caaf1089b77daba7)#z2t3ypsa'])
 
 if __name__ == '__main__':
     ScantxoutsetTest().main()
diff --git a/test/functional/test_framework/descriptors.py b/test/functional/test_framework/descriptors.py
new file mode 100644
index 0000000000..29482ce01e
--- /dev/null
+++ b/test/functional/test_framework/descriptors.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 Pieter Wuille
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Utility functions related to output descriptors"""
+
+INPUT_CHARSET = "0123456789()[],'/*abcdefgh@:$%{}IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~ijklmnopqrstuvwxyzABCDEFGH`#\"\\ "
+CHECKSUM_CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
+GENERATOR = [0xf5dee51989, 0xa9fdca3312, 0x1bab10e32d, 0x3706b1677a, 0x644d626ffd]
+
+def descsum_polymod(symbols):
+    """Internal function that computes the descriptor checksum."""
+    chk = 1
+    for value in symbols:
+        top = chk >> 35
+        chk = (chk & 0x7ffffffff) << 5 ^ value
+        for i in range(5):
+            chk ^= GENERATOR[i] if ((top >> i) & 1) else 0
+    return chk
+
+def descsum_expand(s):
+    """Internal function that does the character to symbol expansion"""
+    groups = []
+    symbols = []
+    for c in s:
+        if not c in INPUT_CHARSET:
+            return None
+        v = INPUT_CHARSET.find(c)
+        symbols.append(v & 31)
+        groups.append(v >> 5)
+        if len(groups) == 3:
+            symbols.append(groups[0] * 9 + groups[1] * 3 + groups[2])
+            groups = []
+    if len(groups) == 1:
+        symbols.append(groups[0])
+    elif len(groups) == 2:
+        symbols.append(groups[0] * 3 + groups[1])
+    return symbols
+
+def descsum_create(s):
+    """Add a checksum to a descriptor without"""
+    symbols = descsum_expand(s) + [0, 0, 0, 0, 0, 0, 0, 0]
+    checksum = descsum_polymod(symbols) ^ 1
+    return s + '#' + ''.join(CHECKSUM_CHARSET[(checksum >> (5 * (7 - i))) & 31] for i in range(8))
+
+def descsum_check(s, require=True):
+    """Verify that the checksum is correct in a descriptor"""
+    if not '#' in s:
+        return not require
+    if s[-9] != '#':
+        return False
+    if not all(x in CHECKSUM_CHARSET for x in s[-8:]):
+        return False
+    symbols = descsum_expand(s[:-9]) + [CHECKSUM_CHARSET.find(x) for x in s[-8:]]
+    return descsum_polymod(symbols) == 1
diff --git a/test/functional/wallet_address_types.py b/test/functional/wallet_address_types.py
index bafa556aad..380dd9c0ad 100755
--- a/test/functional/wallet_address_types.py
+++ b/test/functional/wallet_address_types.py
@@ -54,6 +54,10 @@ from decimal import Decimal
 import itertools
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.descriptors import (
+    descsum_create,
+    descsum_check,
+)
 from test_framework.util import (
     assert_equal,
     assert_greater_than,
@@ -167,24 +171,31 @@ class AddressTypeTest(BitcoinTestFramework):
             assert_equal(deriv['path'][0], 'm')
             key_descs[deriv['pubkey']] = '[' + deriv['master_fingerprint'] + deriv['path'][1:] + ']' + deriv['pubkey']
 
+        # Verify the descriptor checksum against the Python implementation
+        assert(descsum_check(info['desc']))
+        # Verify that stripping the checksum and recreating it using Python roundtrips
+        assert(info['desc'] == descsum_create(info['desc'][:-9]))
+        # Verify that stripping the checksum and feeding it to getdescriptorinfo roundtrips
+        assert(info['desc'] == self.nodes[0].getdescriptorinfo(info['desc'][:-9])['descriptor'])
+
         if not multisig and typ == 'legacy':
             # P2PKH
-            assert_equal(info['desc'], "pkh(%s)" % key_descs[info['pubkey']])
+            assert_equal(info['desc'], descsum_create("pkh(%s)" % key_descs[info['pubkey']]))
         elif not multisig and typ == 'p2sh-segwit':
             # P2SH-P2WPKH
-            assert_equal(info['desc'], "sh(wpkh(%s))" % key_descs[info['pubkey']])
+            assert_equal(info['desc'], descsum_create("sh(wpkh(%s))" % key_descs[info['pubkey']]))
         elif not multisig and typ == 'bech32':
             # P2WPKH
-            assert_equal(info['desc'], "wpkh(%s)" % key_descs[info['pubkey']])
+            assert_equal(info['desc'], descsum_create("wpkh(%s)" % key_descs[info['pubkey']]))
         elif typ == 'legacy':
             # P2SH-multisig
-            assert_equal(info['desc'], "sh(multi(2,%s,%s))" % (key_descs[info['pubkeys'][0]], key_descs[info['pubkeys'][1]]))
+            assert_equal(info['desc'], descsum_create("sh(multi(2,%s,%s))" % (key_descs[info['pubkeys'][0]], key_descs[info['pubkeys'][1]])))
         elif typ == 'p2sh-segwit':
             # P2SH-P2WSH-multisig
-            assert_equal(info['desc'], "sh(wsh(multi(2,%s,%s)))" % (key_descs[info['embedded']['pubkeys'][0]], key_descs[info['embedded']['pubkeys'][1]]))
+            assert_equal(info['desc'], descsum_create("sh(wsh(multi(2,%s,%s)))" % (key_descs[info['embedded']['pubkeys'][0]], key_descs[info['embedded']['pubkeys'][1]])))
         elif typ == 'bech32':
             # P2WSH-multisig
-            assert_equal(info['desc'], "wsh(multi(2,%s,%s))" % (key_descs[info['pubkeys'][0]], key_descs[info['pubkeys'][1]]))
+            assert_equal(info['desc'], descsum_create("wsh(multi(2,%s,%s))" % (key_descs[info['pubkeys'][0]], key_descs[info['pubkeys'][1]])))
         else:
             # Unknown type
             assert(False)
diff --git a/test/functional/wallet_importmulti.py b/test/functional/wallet_importmulti.py
index 46e3ab77c8..8e25aa7337 100755
--- a/test/functional/wallet_importmulti.py
+++ b/test/functional/wallet_importmulti.py
@@ -20,6 +20,7 @@ from test_framework.script import (
     OP_NOP,
 )
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.descriptors import descsum_create
 from test_framework.util import (
     assert_equal,
     assert_greater_than,
@@ -545,11 +546,22 @@ class ImportMultiTest(BitcoinTestFramework):
 
         # Test importing of a P2SH-P2WPKH address via descriptor + private key
         key = get_key(self.nodes[0])
-        self.log.info("Should import a p2sh-p2wpkh address from descriptor and private key")
+        self.log.info("Should not import a p2sh-p2wpkh address from descriptor without checksum and private key")
         self.test_importmulti({"desc": "sh(wpkh(" + key.pubkey + "))",
                                "timestamp": "now",
                                "label": "Descriptor import test",
                                "keys": [key.privkey]},
+                              success=False,
+                              error_code=-5,
+                              error_message="Descriptor is invalid")
+
+        # Test importing of a P2SH-P2WPKH address via descriptor + private key
+        key = get_key(self.nodes[0])
+        self.log.info("Should import a p2sh-p2wpkh address from descriptor and private key")
+        self.test_importmulti({"desc": descsum_create("sh(wpkh(" + key.pubkey + "))"),
+                               "timestamp": "now",
+                               "label": "Descriptor import test",
+                               "keys": [key.privkey]},
                               success=True)
         test_address(self.nodes[1],
                      key.p2sh_p2wpkh_addr,
@@ -562,7 +574,7 @@ class ImportMultiTest(BitcoinTestFramework):
         addresses = ["2N7yv4p8G8yEaPddJxY41kPihnWvs39qCMf", "2MsHxyb2JS3pAySeNUsJ7mNnurtpeenDzLA"] # hdkeypath=m/0'/0'/0' and 1'
         desc = "sh(wpkh(" + xpriv + "/0'/0'/*'" + "))"
         self.log.info("Ranged descriptor import should fail without a specified range")
-        self.test_importmulti({"desc": desc,
+        self.test_importmulti({"desc": descsum_create(desc),
                                "timestamp": "now"},
                               success=False,
                               error_code=-8,
@@ -570,7 +582,7 @@ class ImportMultiTest(BitcoinTestFramework):
 
         # Test importing of a ranged descriptor without keys
         self.log.info("Should import the ranged descriptor with specified range as solvable")
-        self.test_importmulti({"desc": desc,
+        self.test_importmulti({"desc": descsum_create(desc),
                                "timestamp": "now",
                                "range": {"end": 1}},
                               success=True,
@@ -583,7 +595,7 @@ class ImportMultiTest(BitcoinTestFramework):
         # Test importing of a P2PKH address via descriptor
         key = get_key(self.nodes[0])
         self.log.info("Should import a p2pkh address from descriptor")
-        self.test_importmulti({"desc": "pkh(" + key.pubkey + ")",
+        self.test_importmulti({"desc": descsum_create("pkh(" + key.pubkey + ")"),
                                "timestamp": "now",
                                "label": "Descriptor import test"},
                               True,
@@ -597,7 +609,7 @@ class ImportMultiTest(BitcoinTestFramework):
         # Test import fails if both desc and scriptPubKey are provided
         key = get_key(self.nodes[0])
         self.log.info("Import should fail if both scriptPubKey and desc are provided")
-        self.test_importmulti({"desc": "pkh(" + key.pubkey + ")",
+        self.test_importmulti({"desc": descsum_create("pkh(" + key.pubkey + ")"),
                                "scriptPubKey": {"address": key.p2pkh_addr},
                                "timestamp": "now"},
                               success=False,
@@ -616,7 +628,7 @@ class ImportMultiTest(BitcoinTestFramework):
         key1 = get_key(self.nodes[0])
         key2 = get_key(self.nodes[0])
         self.log.info("Should import a 1-of-2 bare multisig from descriptor")
-        self.test_importmulti({"desc": "multi(1," + key1.pubkey + "," + key2.pubkey + ")",
+        self.test_importmulti({"desc": descsum_create("multi(1," + key1.pubkey + "," + key2.pubkey + ")"),
                                "timestamp": "now"},
                               success=True)
         self.log.info("Should not treat individual keys from the imported bare multisig as watchonly")
@@ -635,7 +647,7 @@ class ImportMultiTest(BitcoinTestFramework):
         pub_fpr = info['hdmasterfingerprint']
         result = self.nodes[0].importmulti(
             [{
-                'desc' : "wpkh([" + pub_fpr + pub_keypath[1:] +"]" + pub + ")",
+                'desc' : descsum_create("wpkh([" + pub_fpr + pub_keypath[1:] +"]" + pub + ")"),
                 "timestamp": "now",
             }]
         )
@@ -653,7 +665,7 @@ class ImportMultiTest(BitcoinTestFramework):
         priv_fpr = info['hdmasterfingerprint']
         result = self.nodes[0].importmulti(
             [{
-                'desc' : "wpkh([" + priv_fpr + priv_keypath[1:] + "]" + priv + ")",
+                'desc' : descsum_create("wpkh([" + priv_fpr + priv_keypath[1:] + "]" + priv + ")"),
                 "timestamp": "now",
             }]
         )
@@ -701,12 +713,12 @@ class ImportMultiTest(BitcoinTestFramework):
         pub2 = self.nodes[0].getaddressinfo(addr2)['pubkey']
         result = wrpc.importmulti(
             [{
-                'desc': 'wpkh(' + pub1 + ')',
+                'desc': descsum_create('wpkh(' + pub1 + ')'),
                 'keypool': True,
                 "timestamp": "now",
             },
             {
-                'desc': 'wpkh(' + pub2 + ')',
+                'desc': descsum_create('wpkh(' + pub2 + ')'),
                 'keypool': True,
                 "timestamp": "now",
             }]
@@ -727,13 +739,13 @@ class ImportMultiTest(BitcoinTestFramework):
         pub2 = self.nodes[0].getaddressinfo(addr2)['pubkey']
         result = wrpc.importmulti(
             [{
-                'desc': 'wpkh(' + pub1 + ')',
+                'desc': descsum_create('wpkh(' + pub1 + ')'),
                 'keypool': True,
                 'internal': True,
                 "timestamp": "now",
             },
             {
-                'desc': 'wpkh(' + pub2 + ')',
+                'desc': descsum_create('wpkh(' + pub2 + ')'),
                 'keypool': True,
                 'internal': True,
                 "timestamp": "now",
@@ -755,7 +767,7 @@ class ImportMultiTest(BitcoinTestFramework):
         pub2 = self.nodes[0].getaddressinfo(addr2)['pubkey']
         result = wrpc.importmulti(
             [{
-                'desc': 'wsh(multi(2,' + pub1 + ',' + pub2 + '))',
+                'desc': descsum_create('wsh(multi(2,' + pub1 + ',' + pub2 + '))'),
                 'keypool': True,
                 "timestamp": "now",
             }]
@@ -769,7 +781,7 @@ class ImportMultiTest(BitcoinTestFramework):
         assert wrpc.getwalletinfo()['private_keys_enabled']
         result = wrpc.importmulti(
             [{
-                'desc': 'wpkh(' + pub1 + ')',
+                'desc': descsum_create('wpkh(' + pub1 + ')'),
                 'keypool': True,
                 "timestamp": "now",
             }]
@@ -792,7 +804,7 @@ class ImportMultiTest(BitcoinTestFramework):
         ]
         result = wrpc.importmulti(
             [{
-                'desc': 'wpkh([80002067/0h/0h]' + xpub + '/*)',
+                'desc': descsum_create('wpkh([80002067/0h/0h]' + xpub + '/*)'),
                 'keypool': True,
                 'timestamp': 'now',
                 'range' : {'start': 0, 'end': 4}