数字签名

v0.3.38 新增。PDF Oxide 从 /AcroForm /Fields → /Sig 读取签名，检查 /Contents 内的 CMS 封装，对嵌入证书执行 RFC 5652 §5.4 签名者属性校验，并对调用方提供的文档字节执行 §11.2 messageDigest 校验。

范围说明。 本页介绍现有签名的读取与验证：枚举、CMS 加密校验、PAdES 级别分类、DSS 检查以及 RFC 3161 时间戳。若要创建签名 — 加载 PKCS#12/PEM 凭证并生成 CMS 或 PAdES B-B/B-T/B-LT 签名 — 请参阅 为 PDF 签名：数字签名与 PAdES（v0.3.50 发布，issue #235）。

验证内容

• RSA-PKCS#1 v1.5 over SHA-1 / SHA-256 / SHA-384 / SHA-512 — 几乎所有已签名 PDF 所用的填充方案 — 返回 Valid / Invalid。
• RSA-PSS 和 ECDSA 以 Unknown / UnsupportedFeatureException 形式返回。需要这些算法的调用方仍可通过 Signature.GetCertificate() / .get_certificate() 读取嵌入证书并自行校验。
• 信任根查找、有效期窗口和签名者 DN 均来自嵌入证书，并写入验证结果。

快速示例

Rust

use pdf_oxide::PdfDocument;

let doc = PdfDocument::open("signed.pdf")?;
for sig in doc.signatures() {
    println!("{} → {:?}", sig.signer_name(), sig.verify()?);

    // End-to-end with document bytes
    let pdf_bytes = std::fs::read("signed.pdf")?;
    println!("detached ok = {:?}", sig.verify_detached(&pdf_bytes)?);

    // Cert inspection + trust-root / expiry / signer DN
    let result = pdf_oxide::SignatureVerifier::verify(&sig, &pdf_bytes)?;
    println!("signer DN = {}", result.signer_dn);
}

Python

from pdf_oxide import PdfDocument

doc = PdfDocument("signed.pdf")
for sig in doc.signatures():
    print(sig.signer_name, "→", sig.verify())

# End-to-end with document bytes
with open("signed.pdf", "rb") as f:
    pdf_bytes = f.read()
for sig in doc.signatures():
    print("detached ok =", sig.verify_detached(pdf_bytes))

Node / TypeScript

import { PdfDocument } from "pdf-oxide";
import { readFileSync } from "fs";

const doc = PdfDocument.open("signed.pdf");
for (const sig of doc.signatures()) {
  console.log(sig.signerName, "→", sig.verify());
  console.log("detached ok =", sig.verifyDetached(readFileSync("signed.pdf")));
}

C#

using PdfOxide;

using var doc = PdfDocument.Open("signed.pdf");
foreach (var sig in doc.Signatures)
{
    Console.WriteLine($"{sig.SignerName} → {sig.Verify()}");
    var cert = sig.GetCertificate();
    Console.WriteLine($"subject={cert.Subject} issuer={cert.Issuer} valid={cert.IsValid}");
}

Go (CGo-only)

import (
    "fmt"
    "os"

    pdfoxide "github.com/yfedoseev/pdf_oxide/go"
)

doc, _ := pdfoxide.Open("signed.pdf")
defer doc.Close()

pdfBytes, _ := os.ReadFile("signed.pdf")

sigs, _ := doc.Signatures()
for _, sig := range sigs {
    ok, _ := sig.Verify()
    fmt.Printf("%s → %v\n", sig.SignerName, ok)

    // End-to-end with document bytes
    detachedOk, _ := sig.VerifyDetached(pdfBytes)
    fmt.Println("detached ok =", detachedOk)
}

WASM

import init, { PdfDocument } from "pdf-oxide-wasm/web";
await init();

const doc = new PdfDocument(bytes);
for (const sig of doc.signatures()) {
  console.log(sig.signerName, "→", sig.verify());
}

C++

#include <pdf_oxide/pdf_oxide.hpp>
#include <fstream>

auto doc = pdf_oxide::Document::open("signed.pdf");

std::ifstream f("signed.pdf", std::ios::binary);
std::vector<std::uint8_t> pdf_bytes((std::istreambuf_iterator<char>(f)), {});

for (int i = 0; i < doc.get_signature_count(); ++i) {
    auto sig = doc.get_signature(i);
    std::cout << sig.signer_name() << " → " << sig.verify() << "\n";   // 1 valid / 0 invalid / -1 unknown
    std::cout << "detached ok = " << sig.verify_detached(pdf_bytes) << "\n";
}

Swift

import PdfOxide
import Foundation

let doc = try Document.open("signed.pdf")
let pdfBytes = [UInt8](try Data(contentsOf: URL(fileURLWithPath: "signed.pdf")))

for i in 0..<(try doc.signatureCount()) {
    guard let sig = try doc.signature(i) else { continue }
    print(try sig.signerName(), "→", try sig.verify())   // 1 valid / 0 invalid / -1 unknown
    print("detached ok =", try sig.verifyDetached(pdfBytes))
}

Dart

import 'dart:io';
import 'package:pdf_oxide/pdf_oxide.dart';

final doc = PdfDocument.open('signed.pdf');
final pdfBytes = File('signed.pdf').readAsBytesSync();

for (var i = 0; i < doc.getSignatureCount(); i++) {
  final sig = doc.getSignature(i);
  print('${sig.signerName} → ${sig.verify()}');   // 1 valid / 0 invalid / -1 unknown
  print('detached ok = ${sig.verifyDetached(pdfBytes)}');
}

R

library(pdfoxide)

doc <- pdf_open("signed.pdf")
pdf_bytes <- readBin("signed.pdf", "raw", file.info("signed.pdf")$size)

for (i in seq_len(pdf_signature_count(doc)) - 1L) {
  sig <- pdf_get_signature(doc, i)
  cat(pdf_signature_signer_name(sig), "→", pdf_signature_verify(sig), "\n")  # 1 valid / 0 invalid / -1 unknown
  cat("detached ok =", pdf_signature_verify_detached(sig, pdf_bytes), "\n")
}

Julia

using PdfOxide

doc = open_document("signed.pdf")
pdf_bytes = read("signed.pdf")

for i in 0:(get_signature_count(doc) - 1)
    sig = get_signature(doc, i)
    println(signature_get_signer_name(sig), " → ", signature_verify(sig))   # 1 valid / 0 invalid / -1 unknown
    println("detached ok = ", signature_verify_detached(sig, pdf_bytes))
end

Zig

const pdf_oxide = @import("pdf_oxide");
const a = std.heap.page_allocator;

var doc = try pdf_oxide.Document.open("signed.pdf");
const pdf_bytes = try std.fs.cwd().readFileAlloc(a, "signed.pdf", 1 << 30);

var i: i32 = 0;
const count = try doc.signatureCount();
while (i < count) : (i += 1) {
    var sig = try doc.signature(i);
    const name = try sig.signerName(a);
    std.debug.print("{s} → {}\n", .{ name, try sig.verify() });   // 1 valid / 0 invalid / -1 unknown
    std.debug.print("detached ok = {}\n", .{try sig.verifyDetached(pdf_bytes)});
}

Objective-C

#import "POXPdfOxide.h"
NSError *err = nil;

POXDocument *doc = [POXDocument openPath:@"signed.pdf" error:&err];
NSData *pdfBytes = [NSData dataWithContentsOfFile:@"signed.pdf"];

int32_t count = [doc signatureCountWithError:&err];
for (int32_t i = 0; i < count; i++) {
    POXSignatureInfo *sig = [doc signatureAtIndex:i error:&err];
    NSLog(@"%@ → %d", [sig signerNameError:&err], [sig verifyError:&err]);   // 1 valid / 0 invalid / -1 unknown
    NSLog(@"detached ok = %d", [sig verifyDetached:pdfBytes error:&err]);
}

Elixir

{:ok, doc} = PdfOxide.open("signed.pdf")
pdf_bytes = File.read!("signed.pdf")

{:ok, count} = PdfOxide.signature_count(doc)
for i <- 0..(count - 1) do
  {:ok, sig} = PdfOxide.signature(doc, i)
  {:ok, name} = PdfOxide.signature_signer_name(sig)
  {:ok, verdict} = PdfOxide.signature_verify(sig)          # 1 valid / 0 invalid / -1 unknown
  {:ok, detached} = PdfOxide.signature_verify_detached(sig, pdf_bytes)
  IO.puts("#{name} → #{verdict}")
  IO.puts("detached ok = #{detached}")
end

Signature

枚举并检查签名。所有绑定均支持。

属性 / 方法	说明
.signer_name / .SignerName	签名者证书中的 Common Name。C ABI / Swift 访问器：signing_name / signerName()。
.reason / .Reason	签名原因（例如"我批准此文档"）。C ABI / Swift 访问器：signing_reason / signingReason()。
.location / .Location	位置字段。C ABI / Swift 访问器：signing_location / signingLocation()。
.contact_info	联系信息字段
.signing_time / .SigningTime	CMS 封装中的 UTC 签名时间（C# 中为 DateTimeOffset?）
.pades_level / padesLevel()	仅基于 CMS 属性分类的 PAdES 基线（B_B/B_T）。B_LT 还需要文档 /DSS — 与下方 dss 结合使用。
.has_timestamp() / hasTimestamp()	若该签名包含嵌入的 RFC 3161 时间戳则为 True。
.add_timestamp(ts) / addTimestamp(_:)	将已解析的 Timestamp 附加到签名（C ABI / Swift）。
.verify() / .Verify()	对嵌入证书执行 RFC 5652 §5.4 签名者属性校验，返回 Valid / Invalid / Unknown。
.verify_detached(pdf_bytes) / .VerifyDetached(pdfBytes)	在调用方提供的文档字节上额外执行 RFC 5652 §11.2 messageDigest 校验。
.get_certificate() / .GetCertificate()	返回 Certificate 对象以供深入检查。

在文档层面，verify_all_signatures() / verifyAllSignatures() 对每个签名运行签名者校验，并返回单一汇总结果：1 = 全部有效，0 = 至少一个无效，-1 = 至少一个未知/不支持。

use pdf_oxide::PdfDocument;

let doc = PdfDocument::open("signed.pdf")?;
for sig in doc.signatures() {
    println!("level={:?} timestamped={}", sig.pades_level(), sig.has_timestamp());
}

Certificate

通过 x509-parser 从 /Contents 二进制块中提取 X.509 证书。自 v0.3.38 起在所有绑定中可用（Python / Go / WASM 访问器在首次发布后随即上线）。

属性 / 方法	说明
.subject	证书持有者的 Distinguished Name
.issuer	颁发 CA 的 DN
.serial	序列号（大端字节序或字符串形式）
.not_before	有效期开始（DateTimeOffset）
.not_after	有效期结束
.is_valid	not_before ≤ now ≤ not_after 时为 True

Dss — Document Security Store

/DSS（ISO 32000-2 §12.8.4.3）保存 PAdES-B-LT 签名的长期验证材料：文档级 DER 证书、CRL、OCSP 响应以及每个签名的 VRI 键。从文档中读取；None/null 表示 PDF 没有 DSS（不是错误）。Rust、Python、Go、C#、Swift 中可用。

Rust

use pdf_oxide::PdfDocument;
use pdf_oxide::signatures::read_dss;

let doc = PdfDocument::open("ltv.pdf")?;
if let Some(dss) = read_dss(&doc)? {
    println!("certs={} crls={} ocsps={} vri={}",
        dss.certificates.len(), dss.crls.len(), dss.ocsp_responses.len(), dss.vri.len());
}

Python

import pdf_oxide

doc = pdf_oxide.PdfDocument("ltv.pdf")
dss = doc.dss()
if dss is not None:
    print("certs", len(dss.certs), "crls", len(dss.crls),
          "ocsps", len(dss.ocsps), "vri", len(dss.vri))

Go

doc, _ := pdfoxide.Open("ltv.pdf")
defer doc.Close()

dss, _ := doc.DSS()           // nil when the PDF has no /DSS
if dss != nil {
    fmt.Printf("certs=%d crls=%d ocsps=%d vri=%d\n",
        len(dss.Certs), len(dss.CRLs), len(dss.OCSPs), dss.VRICount)
}

C#

using var doc = PdfDocument.Open("ltv.pdf");
var dss = doc.GetDss();        // null when the PDF has no /DSS
if (dss is not null)
{
    Console.WriteLine($"certs={dss.Certificates.Count} crls={dss.Crls.Count} " +
                      $"ocsps={dss.OcspResponses.Count} vri={dss.VriCount}");
}

Swift

if let dss = try doc.dss() {
    print("certs=\(try dss.certCount()) crls=\(try dss.crlCount()) " +
          "ocsps=\(try dss.ocspCount()) vri=\(try dss.vriCount())")
}

C++

try {
    auto dss = doc.get_dss();           // throws if the PDF has no /DSS
    std::cout << "certs=" << dss.cert_count() << " crls=" << dss.crl_count()
              << " ocsps=" << dss.ocsp_count() << " vri=" << dss.vri_count() << "\n";
} catch (const pdf_oxide::Error&) {
    // no DSS present
}

Dart

try {
  final dss = doc.getDss();             // throws if the PDF has no /DSS
  print('certs=${dss.certCount} crls=${dss.crlCount} '
        'ocsps=${dss.ocspCount} vri=${dss.vriCount}');
} on PdfOxideError {
  // no DSS present
}

R

dss <- pdf_get_dss(doc)                 # NULL when the PDF has no /DSS
if (!is.null(dss)) {
  cat("certs=", pdf_dss_cert_count(dss), "crls=", pdf_dss_crl_count(dss),
      "ocsps=", pdf_dss_ocsp_count(dss), "vri=", pdf_dss_vri_count(dss), "\n")
}

Julia

dss = document_get_dss(doc)             # nothing when the PDF has no /DSS
if dss !== nothing
    println("certs=", dss_cert_count(dss), " crls=", dss_crl_count(dss),
            " ocsps=", dss_ocsp_count(dss), " vri=", dss_vri_count(dss))
end

Zig

var dss = try doc.dss();                // error if the PDF has no /DSS
std.debug.print("certs={} crls={} ocsps={} vri={}\n", .{
    try dss.certCount(), try dss.crlCount(), try dss.ocspCount(), try dss.vriCount(),
});

Objective-C

POXDss *dss = [doc dssWithError:&err];  // nil when the PDF has no /DSS
if (dss != nil) {
    NSLog(@"certs=%d crls=%d ocsps=%d vri=%d",
          [dss certCount], [dss crlCount], [dss ocspCount], [dss vriCount]);
}

Elixir

case PdfOxide.document_dss(doc) do
  {:ok, dss} ->
    IO.puts("certs=#{PdfOxide.dss_cert_count(dss)} crls=#{PdfOxide.dss_crl_count(dss)} " <>
            "ocsps=#{PdfOxide.dss_ocsp_count(dss)} vri=#{PdfOxide.dss_vri_count(dss)}")
  _ -> :no_dss   # the PDF has no /DSS
end

C ABI / Swift 方法	Python / Go / C# 等价	说明
cert_count()	len(dss.certs) / len(dss.Certs) / dss.Certificates.Count	文档级 DER 证书（/Certs）
crl_count()	len(dss.crls) / len(dss.CRLs) / dss.Crls.Count	文档级 DER CRL（/CRLs）
ocsp_count()	len(dss.ocsps) / len(dss.OCSPs) / dss.OcspResponses.Count	文档级 DER OCSP 响应（/OCSPs）
vri_count()	len(dss.vri) / dss.VRICount / dss.VriCount	每个签名的 /VRI 条目（/Contents 大写十六进制 SHA-1）

要检查 B-LTA 归档 /DocTimeStamp（pades_level 无法报告的文档级信号），请调用 has_document_timestamp(pdf_bytes)（Rust/Python）、doc.HasDocumentTimestamp()（Go/C#）或 doc.hasTimestamp()（Swift）。

Timestamp — RFC 3161 TSTInfo

从签名的 TimeStampToken 属性或独立的 RFC 3161 响应中解析时间戳二进制块。所有绑定均支持（Node 支持在 v0.3.38 发布后添加）。

Rust

use pdf_oxide::Timestamp;

let ts = Timestamp::parse(&tst_bytes)?;
println!("{} serial={} tsa={}", ts.time(), ts.serial(), ts.tsa_name());

Python

from pdf_oxide import Timestamp

ts = Timestamp.parse(tst_bytes)
print(ts.time, ts.serial, ts.policy_oid, ts.tsa_name, ts.hash_algorithm)

C#

var ts = Timestamp.Parse(tstBytes);
Console.WriteLine($"{ts.Time} serial={ts.Serial} tsa={ts.TsaName}");

Node / TypeScript

import { Timestamp } from "pdf-oxide";

const ts = Timestamp.parse(tstBytes);
console.log(ts.time, ts.serial, ts.policyOid, ts.tsaName, ts.hashAlgorithm);
ts.close();

Go

ts, _ := pdfoxide.ParseTimestamp(tstBytes)
fmt.Println(ts.Time, ts.Serial, ts.PolicyOid, ts.TsaName, ts.HashAlgorithm)

WASM

import init, { Timestamp } from "pdf-oxide-wasm/web";
await init();

const ts = Timestamp.parse(tstBytes);
console.log(ts.time, ts.serial, ts.policyOid, ts.tsaName, ts.hashAlgorithm);

C++

auto ts = pdf_oxide::Timestamp::parse(tst_bytes);
std::cout << ts.time() << " serial=" << ts.serial() << " tsa=" << ts.tsa_name()
          << " policy=" << ts.policy_oid() << " hash=" << ts.hash_algorithm() << "\n";

Swift

let ts = try Timestamp.parse(tstBytes)
print(try ts.time(), "serial=\(try ts.serial())", "tsa=\(try ts.tsaName())",
      "policy=\(try ts.policyOid())", "hash=\(try ts.hashAlgorithm())")

Dart

final ts = Timestamp.parse(tstBytes);
print('${ts.time} serial=${ts.serial} tsa=${ts.tsaName} '
      'policy=${ts.policyOid} hash=${ts.hashAlgorithm}');

R

ts <- pdf_timestamp_parse(tst_bytes)
cat(pdf_timestamp_time(ts), "serial=", pdf_timestamp_serial(ts),
    "tsa=", pdf_timestamp_tsa_name(ts), "policy=", pdf_timestamp_policy_oid(ts),
    "hash=", pdf_timestamp_hash_algorithm(ts), "\n")

Julia

ts = timestamp_parse(tst_bytes)
println(timestamp_get_time(ts), " serial=", timestamp_get_serial(ts),
        " tsa=", timestamp_get_tsa_name(ts), " policy=", timestamp_get_policy_oid(ts),
        " hash=", timestamp_get_hash_algorithm(ts))

Zig

const a = std.heap.page_allocator;
var ts = try pdf_oxide.Timestamp.parse(tst_bytes);
const serial = try ts.serial(a);
const tsa = try ts.tsaName(a);
std.debug.print("{} serial={s} tsa={s} hash={}\n", .{
    try ts.time(), serial, tsa, try ts.hashAlgorithm(),
});

Objective-C

POXTimestamp *ts = [POXTimestamp parse:tstBytes error:&err];
NSLog(@"%lld serial=%@ tsa=%@ policy=%@ hash=%d",
      [ts timeError:&err], [ts serialError:&err], [ts tsaNameError:&err],
      [ts policyOidError:&err], [ts hashAlgorithmError:&err]);

Elixir

{:ok, ts} = PdfOxide.timestamp_parse(tst_bytes)
{:ok, time}   = PdfOxide.timestamp_time(ts)
{:ok, serial} = PdfOxide.timestamp_serial(ts)
{:ok, tsa}    = PdfOxide.timestamp_tsa_name(ts)
IO.puts("#{time} serial=#{serial} tsa=#{tsa}")

属性	说明
.time	TSA 声明的 UTC 时间
.serial	本时间戳的唯一序列号
.policy_oid	TSA 策略 OID
.tsa_name	TSA 标识符
.hash_algorithm	message_imprint 所用的哈希算法
.message_imprint	已签名负载的哈希值
.verify()	对嵌入 TSA 证书校验 TSTInfo 签名

TsaClient — RFC 3161 HTTP 客户端

通过 HTTP 向时间戳机构请求新时间戳。需要 tsa-client Cargo 特性。除 WASM 外所有绑定均支持（Node 支持在 v0.3.38 发布后添加；WASM 刻意不支持 — ureq 无法编译为 wasm32）。

Rust

use pdf_oxide::TsaClient;

let client = TsaClient::new("https://freetsa.org/tsr")
    .with_timeout(std::time::Duration::from_secs(30))
    .with_hash_algorithm(pdf_oxide::HashAlgorithm::Sha256)
    .with_nonce(true);
let ts = client.request_timestamp(&pdf_bytes)?;
println!("{} serial={}", ts.time(), ts.serial());

Python

from pdf_oxide import TsaClient

client = TsaClient(
    url="https://freetsa.org/tsr",
    username=None,
    password=None,
    timeout_seconds=30,
    hash_algorithm=2,   # 2 = SHA-256
    use_nonce=True,
    cert_req=True,
)

ts = client.request_timestamp(pdf_bytes)
print(ts.time, ts.serial)

Node / TypeScript

import { TsaClient } from "pdf-oxide";

const client = new TsaClient({
  url: "https://freetsa.org/tsr",
  timeoutSeconds: 30,
  hashAlgorithm: 2,    // 2 = SHA-256
  useNonce: true,
  certReq: true,
});

const ts = client.requestTimestamp(pdfBytes);
console.log(ts.time, ts.serial);
ts.close();
client.close();

C#

var client = new TsaClient("https://freetsa.org/tsr");
var ts = client.RequestTimestamp(pdfBytes);
Console.WriteLine($"{ts.Time} serial={ts.Serial}");

Go

client := pdfoxide.NewTsaClient("https://freetsa.org/tsr")
ts, err := client.RequestTimestamp(pdfBytes)
if err != nil { log.Fatal(err) }
fmt.Println(ts.Time, ts.Serial)

C++

auto client = pdf_oxide::TsaClient::create("https://freetsa.org/tsr");
auto ts = client.request_timestamp(pdf_bytes);
std::cout << ts.time() << " serial=" << ts.serial() << "\n";

Swift

let client = try TsaClient.create(url: "https://freetsa.org/tsr")
let ts = try client.requestTimestamp(pdfBytes)
print(try ts.time(), "serial=\(try ts.serial())")

Dart

final client = TsaClient.create('https://freetsa.org/tsr');
final ts = client.requestTimestamp(pdfBytes);
print('${ts.time} serial=${ts.serial}');

R

client <- pdf_tsa_client_create("https://freetsa.org/tsr")
ts <- pdf_tsa_request_timestamp(client, pdf_bytes)
cat(pdf_timestamp_time(ts), "serial=", pdf_timestamp_serial(ts), "\n")

Julia

client = tsa_client_create("https://freetsa.org/tsr")
ts = tsa_request_timestamp(client, pdf_bytes)
println(timestamp_get_time(ts), " serial=", timestamp_get_serial(ts))

Zig

const a = std.heap.page_allocator;
var client = try pdf_oxide.TsaClient.create("https://freetsa.org/tsr", "", "", 30, 0, true, true);
var ts = try client.requestTimestamp(pdf_bytes);
const serial = try ts.serial(a);
std.debug.print("{} serial={s}\n", .{ try ts.time(), serial });

Objective-C

POXTsaClient *client = [POXTsaClient createWithUrl:@"https://freetsa.org/tsr"
                                          username:nil password:nil
                                           timeout:30 hashAlgo:0
                                          useNonce:YES certReq:YES error:&err];
POXTimestamp *ts = [client requestTimestamp:pdfBytes error:&err];
NSLog(@"%lld serial=%@", [ts timeError:&err], [ts serialError:&err]);

Elixir

{:ok, client} = PdfOxide.tsa_client("https://freetsa.org/tsr")
{:ok, ts} = PdfOxide.tsa_request_timestamp(client, pdf_bytes)
{:ok, time}   = PdfOxide.timestamp_time(ts)
{:ok, serial} = PdfOxide.timestamp_serial(ts)
IO.puts("#{time} serial=#{serial}")

TsaClient 通过 HTTP POST 发送 RFC 3161 TimeStampReq，附带随机数和 HTTP Basic 认证（当设置了 username / password 时）。响应被解包并通过 Timestamp::parse 解析。

绑定支持一览

自 v0.3.38 起全面对等：每个签名接口均在所有绑定中可用，唯一例外是 WASM 上的 TsaClient（ureq 与 wasm 不兼容，属设计选择）。

接口	Rust	Python	Node	C#	Go	WASM
Signature 枚举与验证	✓	✓	✓	✓	✓	✓
Certificate 检查	✓	✓	✓	✓	✓	✓
Dss (/DSS) 检查	✓	✓	—	✓	✓	—
Timestamp 解析与验证	✓	✓	✓	✓	✓	✓
TsaClient HTTP 请求	✓	✓	✓	✓	✓	—
签名（sign_pdf_bytes / PAdES）	✓	✓	—	✓	✓	—

TsaClient × WASM 的 — 是刻意且永久的：ureq 无法编译为 wasm32。如需在浏览器中检查响应，请从服务端绑定调用 TsaClient，再将原始时间戳字节传入 WASM 的 Timestamp.parse()。

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