jsontx stuff

CMakeLists.txt

@@ -124,6 +124,9 @@ find_package(date REQUIRED)
 find_package(xxHash REQUIRED)
 find_package(magic_enum REQUIRED)
 
+find_package(fmt REQUIRED)
+target_link_libraries(ripple_libs INTERFACE fmt::fmt)
+
 include(deps/WasmEdge) 
   if(TARGET nudb::core)
   set(nudb nudb::core)

build-core.sh

@@ -95,8 +95,16 @@ if [[ "$4" == "" ]]; then
   echo "Non GH, local building, no Action runner magic"
 else
   # GH Action, runner
-  cp /io/release-build/xahaud /data/builds/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4
-  cp /io/release-build/release.info /data/builds/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4.releaseinfo
+    if [[ "$(git rev-parse --abbrev-ref HEAD)" == "release" ]]; then
+        echo "building on the release branch... placing it in builds/candidate"
+        mkdir /data/builds/candidate
+        cp /io/release-build/xahaud /data/builds/candidate/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4
+        cp /io/release-build/release.info /data/builds/candidate/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4.releaseinfo
+    else
+        echo "building non-release branch, placing it in builds root"
+        cp /io/release-build/xahaud /data/builds/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4
+        cp /io/release-build/release.info /data/builds/$(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4.releaseinfo
+    fi  
   echo "Published build to: http://build.xahau.tech/"
   echo $(date +%Y).$(date +%-m).$(date +%-d)-$(git rev-parse --abbrev-ref HEAD)+$4
 fi

conanfile.py

@@ -35,6 +35,7 @@ class Xrpl(ConanFile):
         'soci/4.0.3@xahaud/stable',
         'xxhash/0.8.2',
         'zlib/1.3.1',
+        'fmt/12.1.0',
     ]
 
     tool_requires = [
@@ -191,6 +192,7 @@ class Xrpl(ConanFile):
             'sqlite3::sqlite',
             'xxhash::xxhash',
             'zlib::zlib',
+            'fmt::fmt',
         ]
         if self.options.rocksdb:
             libxrpl.requires.append('rocksdb::librocksdb')

include/xrpl/protocol/JSONTxSignatures.h

@@ -0,0 +1,557 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012-2014 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_PROTOCOL_JSONTXSIGNATURES_H_INCLUDED
+#define RIPPLE_PROTOCOL_JSONTXSIGNATURES_H_INCLUDED
+
+#include <xrpl/json/json_reader.h>
+#include <xrpl/json/json_writer.h>
+#include <xrpl/protocol/PublicKey.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STParsedJSON.h>
+#include <boost/algorithm/string.hpp>
+#include <algorithm>
+#include <cctype>
+#include <cmath>
+#include <cstdint>
+#include <fmt/format.h>
+#include <limits>
+#include <map>
+#include <functional>
+#include <unordered_map>
+
+namespace ripple {
+
+//------------------------------------------------------------------------------
+// jsontx: plaintext-JSON signing support (featureJsonTx)
+//
+// The delta is attacker-controlled: it arrives over the wire beside a binary
+// transaction and is not covered by the signature it helps reconstruct. Every
+// bound below is therefore explicit, and unsanitize_jsontx accepts only the
+// exact encoding sanitize_jsontx would have produced.
+//------------------------------------------------------------------------------
+
+static constexpr std::size_t jsontx_max_text = 8192;  // canonical and original
+static constexpr std::size_t jsontx_max_diff = 1024;  // delta bytes
+static constexpr std::size_t jsontx_max_ops = 256;    // delta instructions
+static constexpr std::size_t jsontx_min_copy = 4;     // encoder match threshold
+static constexpr std::size_t jsontx_max_cand = 64;    // encoder candidate cap
+
+// Case-insensitive field-name -> canonical SField. Built once from
+// SField::knownCodeToField, the same table doServerDefinitions publishes, using
+// its serializability filter (useful, binary, non-pseudo). sfInvalid if
+// unknown.
+static SField const&
+jsontx_field(std::string const& name)
+{
+    static auto const tbl = [] {
+        std::unordered_map<std::string, SField const*> m;
+        for (auto const& [code, f] : SField::knownCodeToField)
+            if (f->isUseful() && f->isBinary() && f->fieldType < 10000 &&
+                !f->fieldName.empty())
+                m.emplace(boost::algorithm::to_lower_copy(f->fieldName), f);
+        return m;
+    }();
+
+    auto const i = tbl.find(boost::algorithm::to_lower_copy(name));
+    return i == tbl.end() ? sfInvalid : *i->second;
+}
+
+// Civil calendar arithmetic (Howard Hinnant's algorithm), used in both
+// directions. Pure integer maths - no strptime, no timegm, no locale, no
+// tzdata - because these conversions decide whether a signature verifies and
+// so must give the same answer on every node forever.
+static constexpr std::int64_t
+jsontx_days(int y, unsigned m, unsigned d)  // days from 1970-01-01
+{
+    y -= m <= 2;
+    std::int64_t const era = (y >= 0 ? y : y - 399) / 400;
+    unsigned const yoe = static_cast<unsigned>(y - era * 400);
+    unsigned const doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
+    unsigned const doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
+    return era * 146097 + doe - 719468;
+}
+
+static constexpr std::int64_t jsontx_epoch_day = jsontx_days(2000, 1, 1);
+
+// 9999-12-31T23:59:59.999Z: past this toISOString() switches to expanded years
+// (+275760-09-13T...) and the fixed 24 character shape no longer holds
+static constexpr std::uint64_t jsontx_max_time =
+    (static_cast<std::uint64_t>(jsontx_days(9999, 12, 31) - jsontx_epoch_day) *
+         86400 +
+     86399) *
+        1000 +
+    999;
+
+static_assert(jsontx_epoch_day == 10957);  // matches chrono.h epoch_offset
+
+// Strict Date().toISOString() -> milliseconds since the ripple epoch. Exactly
+// YYYY-MM-DDTHH:MM:SS.sssZ, always UTC, always three fractional digits.
+static std::uint64_t
+jsontx_iso(std::string const& s)
+{
+    static constexpr char pat[] = "0000-00-00T00:00:00.000Z";
+    if (s.size() != 24)
+        throw std::runtime_error("jsontx: Time must be an ISO 8601 instant");
+    for (std::size_t i = 0; i < 24; ++i)
+        if (pat[i] == '0' ? !std::isdigit(static_cast<unsigned char>(s[i]))
+                          : s[i] != pat[i])
+            throw std::runtime_error("jsontx: malformed Time");
+
+    auto const n = [&s](std::size_t i, std::size_t c) {
+        int v = 0;
+        while (c--)
+            v = v * 10 + (s[i++] - '0');
+        return v;
+    };
+    int const y = n(0, 4), mo = n(5, 2), d = n(8, 2), h = n(11, 2),
+              mi = n(14, 2), se = n(17, 2), ms = n(20, 3);
+    if (mo < 1 || mo > 12)
+        throw std::runtime_error("jsontx: Time month out of range");
+    bool const leap = (y % 4 == 0 && y % 100 != 0) || y % 400 == 0;
+    int const dim =
+        mo == 2 ? (leap ? 29 : 28) : ((mo % 2 == 1) == (mo <= 7) ? 31 : 30);
+    // 60 is rejected: JS cannot emit a leap second and the ledger cannot
+    // represent one
+    if (d < 1 || d > dim || h > 23 || mi > 59 || se > 59)
+        throw std::runtime_error("jsontx: Time out of range");
+
+    std::int64_t const t = (jsontx_days(y, mo, d) - jsontx_epoch_day) * 86400 +
+        h * 3600 + mi * 60 + se;
+    if (t < 0)
+        throw std::runtime_error("jsontx: Time precedes the ripple epoch");
+    return static_cast<std::uint64_t>(t) * 1000 + ms;
+}
+
+// The exact inverse. Total over [0, jsontx_max_time] and injective, so sfTime
+// and its ISO spelling are two views of one value and the delta carries
+// nothing for the field.
+static std::string
+jsontx_iso_str(std::uint64_t ms)
+{
+    if (ms > jsontx_max_time)
+        throw std::runtime_error("jsontx: Time out of range");
+    std::int64_t const z =
+        static_cast<std::int64_t>(ms / 86400000) + jsontx_epoch_day + 719468;
+    unsigned const tod = static_cast<unsigned>(ms / 1000 % 86400);
+    std::int64_t const era = (z >= 0 ? z : z - 146096) / 146097;
+    unsigned const doe = static_cast<unsigned>(z - era * 146097);
+    unsigned const yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
+    unsigned const doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
+    unsigned const mp = (5 * doy + 2) / 153;
+    unsigned const d = doy - (153 * mp + 2) / 5 + 1;
+    unsigned const m = mp + (mp < 10 ? 3 : -9);
+    return fmt::format(
+        "{:04}-{:02}-{:02}T{:02}:{:02}:{:02}.{:03}Z",
+        static_cast<std::int64_t>(yoe) + era * 400 + (m <= 2),
+        m,
+        d,
+        tod / 3600,
+        tod / 60 % 60,
+        tod % 60,
+        static_cast<unsigned>(ms % 1000));
+}
+
+//------------------------------------------------------------------------------
+// jsoncpp compatibility
+//
+// This is xrpl's vendored jsoncpp, which predates JSON_HAS_INT64: Json::Int is
+// int and Json::UInt is unsigned int, both 32 bit, and there is no isInt64 /
+// asInt64 / asUInt64. Reader::decodeNumber yields intValue or uintValue only
+// while the digits fit in 32 bits; on overflow, and for any token carrying a
+// '.' or an exponent, it falls through to decodeDouble and the number arrives
+// as a realValue.
+//
+// So a large integer is not lost, but it is no longer held as an integer, and
+// the digits the signer wrote are recoverable only while the double is an
+// exact integer view of them. That holds to 2^53; above it consecutive doubles
+// are more than 1 apart and distinct decimal integers collapse onto the same
+// double. Past that point the value is refused rather than guessed at.
+//------------------------------------------------------------------------------
+
+static constexpr double jsontx_exact_max = 9007199254740992.0;  // 2^53
+
+// Exact integer view of a json number. False if v is not a number at all, or
+// is one this build cannot reproduce digit for digit.
+static bool
+jsontx_exact(Json::Value const& v, std::int64_t& out)
+{
+    switch (v.type())
+    {
+        case Json::intValue:
+            out = v.asInt();
+            return true;
+        case Json::uintValue:
+            out = static_cast<std::int64_t>(v.asUInt());
+            return true;
+        case Json::realValue:
+            break;
+        default:  // including booleanValue, which isIntegral() would admit
+            return false;
+    }
+    double const d = v.asDouble();
+    if (!std::isfinite(d) || d != std::trunc(d) || d < -jsontx_exact_max ||
+        d > jsontx_exact_max)
+        return false;
+    out = static_cast<std::int64_t>(d);
+    return true;
+}
+
+// STI_UINT64 renders as a fixed 16 digit hex string and so needs the value
+// unsigned. A negative is refused rather than wrapped: the old
+// static_cast<std::uint64_t>(v.asDouble()) was undefined for a negative or
+// oversized double, and a silent wrap would let -1 and 18446744073709551615
+// canonicalize to the same bytes.
+static std::uint64_t
+jsontx_u64(Json::Value const& v)
+{
+    std::int64_t n = 0;
+    if (!jsontx_exact(v, n) || n < 0)
+        throw std::runtime_error(
+            "jsontx: UInt64 must be an exact non-negative integer");
+    return static_cast<std::uint64_t>(n);
+}
+
+// Renders a javascript number as an exact integer. Anything this build cannot
+// reproduce digit for digit - a fraction, an infinity, a magnitude past 2^53 -
+// is rejected outright: shortest-round-trip rendering of a double is not
+// portable enough to sit in a consensus preimage, and nothing in a transaction
+// needs one. Fractional amounts arrive as strings, which is what the ledger
+// wants anyway.
+static std::string
+jsontx_num(Json::Value const& v)
+{
+    std::int64_t n = 0;
+    if (!jsontx_exact(v, n))
+        throw std::runtime_error("jsontx: number must be an exact integer");
+    return std::to_string(n);
+}
+
+// Returns { sanitized, diff }. `sanitized` is the canonical form: whitespace
+// stripped, field names capitalized to their xahau spelling, members reordered
+// by field code, numbers reformatted per field type. `diff` is a binary delta
+// which, applied to `sanitized` by unsanitize_jsontx, reproduces `raw` byte for
+// byte. Throws on anything it cannot canonicalize.
+static std::pair<std::string, std::string>
+sanitize_jsontx(std::string_view raw)
+{
+    if (raw.size() > jsontx_max_text)
+        throw std::runtime_error("jsontx: document too large");
+
+    Json::Value jv;
+    if (Json::Reader r; !r.parse(raw.data(), raw.data() + raw.size(), jv) ||
+        !jv.isObject())
+        throw std::runtime_error("jsontx: malformed json");
+
+    // (a plain recursive lambda; deducing-this would drop the std::function)
+    std::function<
+        void(Json::Value const&, SerializedTypeID, SField const*, std::string&)>
+        emit = [&](Json::Value const& v,
+                   SerializedTypeID ty,
+                   SField const* fld,
+                   std::string& o) {
+            if (v.isObject())
+            {
+                auto keys = v.getMemberNames();
+                o += '{';
+                if (ty == STI_OBJECT)  // keys are xahau fields
+                {
+                    std::vector<std::pair<SField const*, std::string>> ks;
+                    for (auto const& k : keys)
+                    {
+                        auto const& f = jsontx_field(k);
+                        if (f == sfInvalid)
+                            throw std::runtime_error(
+                                "jsontx: unknown field '" + k + "'");
+                        ks.emplace_back(&f, k);
+                    }
+                    std::sort(
+                        ks.begin(), ks.end(), [](auto const& a, auto const& b) {
+                            return a.first->fieldCode < b.first->fieldCode;
+                        });
+                    for (std::size_t n = 0; n < ks.size(); ++n)
+                    {
+                        auto const& [f, k] = ks[n];
+                        if (n && f == ks[n - 1].first)  // e.g. "Fee" and "fee"
+                            throw std::runtime_error(
+                                "jsontx: duplicate field '" + f->fieldName +
+                                "'");
+                        if (o.back() != '{')
+                            o += ',';
+                        o += Json::valueToQuotedString(f->fieldName.c_str()) +
+                            ':';
+                        emit(v[k], f->fieldType, f, o);
+                    }
+                }
+                else  // amount / issue style subobject: lexicographic, quoted
+                {
+                    std::sort(keys.begin(), keys.end());
+                    for (auto const& k : keys)
+                    {
+                        if (o.back() != '{')
+                            o += ',';
+                        o += Json::valueToQuotedString(k.c_str()) + ':';
+                        emit(v[k], STI_NOTPRESENT, nullptr, o);
+                    }
+                }
+                o += '}';
+            }
+            else if (v.isArray())
+            {
+                o += '[';
+                for (auto const& e : v)
+                {
+                    if (o.back() != '[')
+                        o += ',';
+                    emit(e, STI_OBJECT, nullptr, o);
+                }
+                o += ']';
+            }
+            else if (v.isString())
+            {
+                // Time is spelled Date().toISOString() in the preimage and
+                // stored as an sfTime u64 of milliseconds. Re-emitting the
+                // round-tripped spelling rather than the input is what makes
+                // the canonical form a fixed point: any string that is not
+                // exactly what jsontx_iso_str produces is rejected here.
+                if (fld && *fld == sfTime)
+                    o += Json::valueToQuotedString(
+                        jsontx_iso_str(jsontx_iso(v.asString())).c_str());
+                else
+                    o += Json::valueToQuotedString(v.asCString());
+            }
+            else if (v.isBool())
+                o += v.asBool() ? "true" : "false";
+            else if (v.isNull())
+                throw std::runtime_error("jsontx: null value");
+            else if (ty == STI_UINT8 || ty == STI_UINT16 || ty == STI_UINT32)
+                o += jsontx_num(v);  // small ints stay bare
+            else if (ty == STI_UINT64)
+                o += '"' + fmt::format("{:016X}", jsontx_u64(v)) + '"';
+            else  // amounts, u64, everything else the ledger wants as a string
+                o += Json::valueToQuotedString(jsontx_num(v).c_str());
+        };
+
+    std::string out;
+    emit(jv, STI_OBJECT, nullptr, out);
+
+    // Greedy copy/insert delta over `raw`, sourcing from `out`.
+    //   op 0x00 <varint len> <bytes>       literal
+    //   op 0x01 <varint off> <varint len>  copy from sanitized
+    std::string diff, lit;
+    auto const gram = [](std::string_view s, std::size_t i) {
+        return std::uint32_t(std::uint8_t(s[i])) << 24 |
+            std::uint32_t(std::uint8_t(s[i + 1])) << 16 |
+            std::uint32_t(std::uint8_t(s[i + 2])) << 8 |
+            std::uint32_t(std::uint8_t(s[i + 3]));
+    };
+    auto const varint = [](std::string& o, std::uint64_t v) {
+        do
+        {
+            std::uint8_t const c = v & 0x7F;
+            v >>= 7;
+            o += static_cast<char>(c | (v ? 0x80 : 0));
+        } while (v);
+    };
+    auto const flush = [&] {
+        if (lit.empty())
+            return;
+        diff += char(0);
+        varint(diff, lit.size());
+        diff += lit;
+        lit.clear();
+    };
+
+    // This encoder is normative - unsanitize_jsontx only accepts its exact
+    // output - so it must emit identical bytes on every node and every stdlib.
+    // An unordered container would not: bucket order for equal keys is
+    // unspecified, and with a candidate cap that changes which match wins.
+    std::map<std::uint32_t, std::vector<std::uint32_t>> idx;
+    for (std::size_t i = 0; i + jsontx_min_copy <= out.size(); ++i)
+        idx[gram(out, i)].push_back(i);
+
+    for (std::size_t i = 0; i < raw.size();)
+    {
+        std::size_t bo = 0, bl = 0;
+        if (i + jsontx_min_copy <= raw.size())
+            if (auto const it = idx.find(gram(raw, i)); it != idx.end())
+            {
+                std::size_t tried = 0;
+                for (auto const off : it->second)  // ascending, so ties keep
+                {                                  // the lowest offset
+                    if (++tried > jsontx_max_cand)
+                        break;
+                    std::size_t l = 0;
+                    while (i + l < raw.size() && off + l < out.size() &&
+                           out[off + l] == raw[i + l])
+                        ++l;
+                    if (l > bl)
+                        bl = l, bo = off;
+                }
+            }
+        if (bl >= jsontx_min_copy)
+        {
+            flush();
+            diff += char(1);
+            varint(diff, bo);
+            varint(diff, bl);
+            i += bl;
+        }
+        else
+            lit += raw[i++];
+    }
+    flush();
+
+    return {std::move(out), std::move(diff)};
+}
+
+// Applies an UNTRUSTED delta to a canonical form the node derived itself.
+// Copies read only from `sanitized`, never from the output being built, so a
+// short delta cannot expand geometrically. Offsets and lengths are range
+// checked before use, varints are length- and minimality-bounded, and the two
+// encodings the encoder can never emit - an unmerged literal run, and a copy
+// abutting the previous copy in the source - are rejected. Throws on anything
+// else.
+static std::string
+unsanitize_jsontx(std::string_view sanitized, std::string_view diff)
+{
+    if (sanitized.size() > jsontx_max_text || diff.size() > jsontx_max_diff)
+        throw std::runtime_error("jsontx: oversize delta input");
+
+    std::string out;
+    std::size_t p = 0, ops = 0, prevEnd = 0;
+    int prev = -1;
+
+    auto const varint = [&](std::uint64_t max) -> std::uint64_t {
+        std::uint64_t v = 0;
+        for (int s = 0; s <= 21; s += 7)  // four bytes; caps far under a shift
+        {                                 // wide enough to be undefined
+            if (p >= diff.size())
+                throw std::runtime_error("jsontx: truncated delta");
+            std::uint8_t const c = diff[p++];
+            v |= std::uint64_t(c & 0x7F) << s;
+            if (c & 0x80)
+                continue;
+            if (s && !(c & 0x7F))
+                throw std::runtime_error("jsontx: non-minimal varint");
+            if (v > max)
+                throw std::runtime_error("jsontx: delta value out of range");
+            return v;
+        }
+        throw std::runtime_error("jsontx: overlong varint");
+    };
+
+    while (p < diff.size())
+    {
+        if (++ops > jsontx_max_ops)
+            throw std::runtime_error("jsontx: too many delta ops");
+
+        std::uint8_t const op = diff[p++];
+        if (op > 1)
+            throw std::runtime_error("jsontx: unknown delta op");
+
+        std::size_t n = 0;
+        if (op == 0)  // literal
+        {
+            if (prev == 0)
+                throw std::runtime_error("jsontx: unmerged literal run");
+            n = varint(jsontx_max_text);
+            if (n == 0 || n > diff.size() - p)
+                throw std::runtime_error("jsontx: bad literal length");
+            if (out.size() + n > jsontx_max_text)
+                throw std::runtime_error("jsontx: delta expands too far");
+            out += diff.substr(p, n);
+            p += n;
+        }
+        else  // copy from the canonical form
+        {
+            auto const off = varint(sanitized.size());
+            n = varint(sanitized.size() - off);
+            if (n < jsontx_min_copy)
+                throw std::runtime_error("jsontx: undersize copy");
+            if (prev == 1 && off == prevEnd)
+                throw std::runtime_error("jsontx: unmerged copy run");
+            if (out.size() + n > jsontx_max_text)
+                throw std::runtime_error("jsontx: delta expands too far");
+            out += sanitized.substr(off, n);
+            prevEnd = off + n;
+        }
+        prev = op;
+    }
+
+    if (out.empty())
+        throw std::runtime_error("jsontx: empty delta");
+    return out;
+}
+
+// The complete untrusted-side check, in one place so the RPC path and the
+// relay/consensus path cannot drift. Takes the transaction exactly as it came
+// off the wire and returns the reconstructed preimage.
+static std::string
+jsontx_verify(STTx const& stx, std::string_view diff)
+{
+    if (!stx.isFieldPresent(sfTxnSignature) || stx.isFieldPresent(sfSigners))
+        throw std::runtime_error("jsontx: expects a lone TxnSignature");
+
+    // Out comes everything the signer did not have in front of them: the
+    // signature, and (once the field exists) the delta carrier. SigningPubKey
+    // stays. It being inside the preimage is what binds key to signature and
+    // stops a third party re-signing a captured preimage under their own key.
+    auto txj = stx.STObject::getJson(JsonOptions::none);
+    txj.removeMember(sfTxnSignature.fieldName);
+
+    // sfTime is a u64 of milliseconds on the wire and an ISO 8601 instant in
+    // the preimage. The two are a bijection over the representable range, so
+    // this is a rewrite rather than a reconstruction and the delta carries
+    // nothing for the field.
+    if (stx.isFieldPresent(sfTime))
+        txj[sfTime.fieldName] = jsontx_iso_str(stx.getFieldU64(sfTime));
+
+    auto const pkb = stx.getSigningPubKey();
+    if (publicKeyType(makeSlice(pkb)) != KeyType::ed25519)
+        throw std::runtime_error("jsontx: SigningPubKey must be ed25519");
+
+    // canonical form, derived only from data the node has already validated
+    auto const san = sanitize_jsontx(Json::FastWriter{}.write(txj)).first;
+
+    // reconstruct the signed preimage under the caps above
+    auto const raw = unsanitize_jsontx(san, diff);
+
+    // Bind the preimage to the transaction. This is the load-bearing check,
+    // not a sanity check: a delta of pure literals can reconstruct ANY text,
+    // so without it any ed25519 signature the key ever produced over anything
+    // at all would authorise this transaction. Comparing the delta too - not
+    // just the canonical form - makes the delta a pure function of the
+    // preimage, which rules out a second delta reconstructing the same bytes
+    // and yielding a second valid transaction id.
+    auto const [san2, diff2] = sanitize_jsontx(raw);
+    if (san2 != san || diff2 != diff)
+        throw std::runtime_error("jsontx: preimage does not match transaction");
+
+    if (!verify(
+            PublicKey(makeSlice(pkb)),
+            makeSlice(raw),
+            makeSlice(stx.getFieldVL(sfTxnSignature))))
+        throw std::runtime_error("jsontx: signature does not verify");
+
+    return raw;
+}
+
+}  // namespace ripple
+#endif

include/xrpl/protocol/detail/features.macro

@@ -34,6 +34,7 @@
 // If you add an amendment here, then do not forget to increment `numFeatures`
 // in include/xrpl/protocol/Feature.h.
 
+XRPL_FEATURE(JsonTx,                     Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (HookMap,                    Supported::yes, VoteBehavior::DefaultYes)
 XRPL_FIX    (GuardDepth32,               Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(NamedHooks,                 Supported::yes, VoteBehavior::DefaultNo)

include/xrpl/protocol/detail/sfields.macro

@@ -153,6 +153,7 @@ TYPED_SFIELD(sfOutstandingAmount,        UINT64,    25, SField::sMD_BaseTen|SFie
 TYPED_SFIELD(sfMPTAmount,                UINT64,    26, SField::sMD_BaseTen|SField::sMD_Default)
 TYPED_SFIELD(sfIssuerNode,               UINT64,    27)
 TYPED_SFIELD(sfSubjectNode,              UINT64,    28)
+TYPED_SFIELD(sfTime,                     UINT64,    96)
 TYPED_SFIELD(sfTouchCount,               UINT64,    97)
 TYPED_SFIELD(sfAccountIndex,             UINT64,    98)
 TYPED_SFIELD(sfAccountCount,             UINT64,    99)
@@ -293,6 +294,7 @@ TYPED_SFIELD(sfAssetClass,               VL,        29)
 TYPED_SFIELD(sfProvider,                 VL,        30)
 TYPED_SFIELD(sfMPTokenMetadata,          VL,        31)
 TYPED_SFIELD(sfCredentialType,           VL,        32)
+TYPED_SFIELD(sfJsonTxDelta,              VL,        96)
 TYPED_SFIELD(sfHookName,                 VL,        97)
 TYPED_SFIELD(sfRemarkValue,              VL,        98)
 TYPED_SFIELD(sfRemarkName,               VL,        99)

include/xrpl/protocol/jss.h

@@ -630,6 +630,7 @@ JSS(server_status);             // out: NetworkOPs
 JSS(server_version);            // out: NetworkOPs
 JSS(settle_delay);              // out: AccountChannels
 JSS(severity);                  // in: LogLevel
+JSS(sig);
 JSS(signature);                 // out: NetworkOPs, ChannelAuthorize
 JSS(signature_verified);        // out: ChannelVerify
 JSS(signing_key);               // out: NetworkOPs

src/libxrpl/protocol/TxFormats.cpp

@@ -49,6 +49,8 @@ TxFormats::TxFormats()
         {sfNetworkID, soeOPTIONAL},
         {sfHookParameters, soeOPTIONAL},
         {sfHookName, soeOPTIONAL},
+        {sfTime, soeOPTIONAL},
+        {sfJsonTxDelta, soeOPTIONAL},
     };
 
 #pragma push_macro("UNWRAP")

src/xrpld/rpc/handlers/Submit.cpp

@@ -26,10 +26,17 @@
 #include <xrpld/rpc/GRPCHandlers.h>
 #include <xrpld/rpc/detail/RPCHelpers.h>
 #include <xrpld/rpc/detail/TransactionSign.h>
+#include <xrpl/json/json_reader.h>
+#include <xrpl/json/json_writer.h>
 #include <xrpl/protocol/ErrorCodes.h>
+#include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/RPCErr.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STParsedJSON.h>
 #include <xrpl/resource/Fees.h>
 
+#include <xrpl/protocol/JSONTxSignatures.h>
+
 namespace ripple {
 
 static NetworkOPs::FailHard
@@ -83,7 +90,8 @@ doInject(RPC::JsonContext& context)
 }
 
 // {
-//   tx_blob: <string> XOR tx_json: <object>,
+//   tx_blob: <string> XOR tx_json: <object>
+//              XOR { tx: <json text>, signature: <hex> },
 //   secret: <secret>
 // }
 Json::Value
@@ -91,7 +99,18 @@ doSubmit(RPC::JsonContext& context)
 {
     context.loadType = Resource::feeMediumBurdenRPC;
 
-    if (!context.params.isMember(jss::tx_blob))
+    bool const hasJsonTx = context.ledgerMaster.getCurrentLedger()->rules().enabled(featureJsonTx);
+
+    bool const isJsonTx = !context.params.isMember(jss::tx_blob) &&
+        context.params.isMember(jss::tx) &&
+        context.params.isMember(jss::sig);
+
+    if (isJsonTx && !hasJsonTx)
+        return RPC::make_error(
+            rpcNOT_SUPPORTED, "JsonTx is not enabled yet.");
+    
+
+    if (!context.params.isMember(jss::tx_blob) && !isJsonTx)
     {
         auto const failType = getFailHard(context);
 
@@ -119,18 +138,73 @@ doSubmit(RPC::JsonContext& context)
 
     Json::Value jvResult;
 
-    auto ret = strUnHex(context.params[jss::tx_blob].asString());
+    std::optional<Blob> ret;
+    if (!isJsonTx)
+    {
+        ret = strUnHex(context.params[jss::tx_blob].asString());
 
-    if (!ret || !ret->size())
-        return rpcError(rpcINVALID_PARAMS);
-
-    SerialIter sitTrans(makeSlice(*ret));
+        if (!ret || !ret->size())
+            return rpcError(rpcINVALID_PARAMS);
+    }
 
     std::shared_ptr<STTx const> stTx;
 
     try
     {
-        stTx = std::make_shared<STTx const>(std::ref(sitTrans));
+        if (!isJsonTx)
+        {
+            SerialIter sitTrans(makeSlice(*ret));
+            stTx = std::make_shared<STTx const>(std::ref(sitTrans));
+        }
+        else
+        {
+            std::string const raw = context.params[jss::tx].asString();
+            auto const [san, diff] = sanitize_jsontx(raw);
+            auto const sig = strUnHex(context.params[jss::sig].asString());
+            if (!sig || sig->empty())
+                throw std::runtime_error("JsonTx: bad signature");
+
+            Json::Value jv;
+            if (Json::Reader r; !r.parse(san, jv))
+                throw std::runtime_error("JsonTx: unparsable canonical form");
+
+            // The preimage carries the key but not the signature over itself.
+            for (auto const& n :
+                 {sfTxnSignature.fieldName, sfSigners.fieldName})
+                if (jv.isMember(n))
+                    throw std::runtime_error(
+                        "JsonTx: " + n + " must not appear in tx");
+            if (!jv.isMember(sfSigningPubKey.fieldName))
+                throw std::runtime_error("JsonTx: tx must carry SigningPubKey");
+
+            // Hand the parser the u64 rather than teaching STUInt64 a second
+            // spelling; the ISO form only ever exists in the preimage.
+            std::optional<std::uint64_t> ms;
+            if (jv.isMember(sfTime.fieldName))
+            {
+                ms = jsontx_iso(jv[sfTime.fieldName].asString());
+                jv.removeMember(sfTime.fieldName);
+            }
+
+            STParsedJSONObject parsed("tx_json", jv);
+            if (!parsed.object)
+                throw std::runtime_error(
+                    parsed.error[jss::error_message].asString());
+            if (ms)
+                parsed.object->setFieldU64(sfTime, *ms);
+            parsed.object->setFieldVL(sfTxnSignature, *sig);
+            stTx = std::make_shared<STTx const>(std::move(*parsed.object));
+
+            // Round-trip the binary codec, then run the exact check a relaying
+            // node will run, so this path cannot accept anything the network
+            // would later reject.
+            Serializer s;
+            stTx->add(s);
+            SerialIter si(s.slice());
+            STTx const rt{si};
+            if (jsontx_verify(rt, diff) != raw)
+                throw std::runtime_error("JsonTx: does not round-trip");
+        }
     }
     catch (std::exception& e)
     {
@@ -141,7 +215,9 @@ doSubmit(RPC::JsonContext& context)
     }
 
     {
-        if (!context.app.checkSigs())
+        // JsonTx signs the plaintext preimage rather than the binary one, so
+        // the binary TxnSignature check is satisfied out of band above.
+        if (!context.app.checkSigs() || isJsonTx)
             forceValidity(
                 context.app.getHashRouter(),
                 stTx->getTransactionID(),