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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
// Handling of certificates and keypairs for SSLStreamAdapter's peer mode.
#include <algorithm>
#include <memory>
#include <string>
#include <vector>
#include "webrtc/rtc_base/buffer.h"
#include "webrtc/rtc_base/constructormagic.h"
#include "webrtc/rtc_base/messagedigest.h"
#include "webrtc/rtc_base/timeutils.h"
namespace rtc {
// Forward declaration due to circular dependency with SSLCertificate.
class SSLCertChain;
struct SSLCertificateStats {
SSLCertificateStats(std::string&& fingerprint,
std::string&& fingerprint_algorithm,
std::string&& base64_certificate,
std::unique_ptr<SSLCertificateStats>&& issuer);
std::string fingerprint;
std::string fingerprint_algorithm;
std::string base64_certificate;
std::unique_ptr<SSLCertificateStats> issuer;
// Abstract interface overridden by SSL library specific
// implementations.
// A somewhat opaque type used to encapsulate a certificate.
// Wraps the SSL library's notion of a certificate, with reference counting.
// The SSLCertificate object is pretty much immutable once created.
// (The OpenSSL implementation only does reference counting and
// possibly caching of intermediate results.)
class SSLCertificate {
// Parses and builds a certificate from a PEM encoded string.
// Returns null on failure.
// The length of the string representation of the certificate is
// stored in *pem_length if it is non-null, and only if
// parsing was successful.
// Caller is responsible for freeing the returned object.
static SSLCertificate* FromPEMString(const std::string& pem_string);
virtual ~SSLCertificate() {}
// Returns a new SSLCertificate object instance wrapping the same
// underlying certificate, including its chain if present.
// Caller is responsible for freeing the returned object.
virtual SSLCertificate* GetReference() const = 0;
// Provides the cert chain, or null. The chain includes a copy of each
// certificate, excluding the leaf.
virtual std::unique_ptr<SSLCertChain> GetChain() const = 0;
// Returns a PEM encoded string representation of the certificate.
virtual std::string ToPEMString() const = 0;
// Provides a DER encoded binary representation of the certificate.
virtual void ToDER(Buffer* der_buffer) const = 0;
// Gets the name of the digest algorithm that was used to compute this
// certificate's signature.
virtual bool GetSignatureDigestAlgorithm(std::string* algorithm) const = 0;
// Compute the digest of the certificate given algorithm
virtual bool ComputeDigest(const std::string& algorithm,
unsigned char* digest,
size_t size,
size_t* length) const = 0;
// Returns the time in seconds relative to epoch, 1970-01-01T00:00:00Z (UTC),
// or -1 if an expiration time could not be retrieved.
virtual int64_t CertificateExpirationTime() const = 0;
// Gets information (fingerprint, etc.) about this certificate and its chain
// (if it has a certificate chain). This is used for certificate stats, see
std::unique_ptr<SSLCertificateStats> GetStats() const;
std::unique_ptr<SSLCertificateStats> GetStats(
std::unique_ptr<SSLCertificateStats> issuer) const;
// SSLCertChain is a simple wrapper for a vector of SSLCertificates. It serves
// primarily to ensure proper memory management (especially deletion) of the
// SSLCertificate pointers.
class SSLCertChain {
// These constructors copy the provided SSLCertificate(s), so the caller
// retains ownership.
explicit SSLCertChain(const std::vector<SSLCertificate*>& certs);
explicit SSLCertChain(const SSLCertificate* cert);
// Vector access methods.
size_t GetSize() const { return certs_.size(); }
// Returns a temporary reference, only valid until the chain is destroyed.
const SSLCertificate& Get(size_t pos) const { return *(certs_[pos]); }
// Returns a new SSLCertChain object instance wrapping the same underlying
// certificate chain. Caller is responsible for freeing the returned object.
SSLCertChain* Copy() const {
return new SSLCertChain(certs_);
// Helper function for duplicating a vector of certificates.
static SSLCertificate* DupCert(const SSLCertificate* cert) {
return cert->GetReference();
// Helper function for deleting a vector of certificates.
static void DeleteCert(SSLCertificate* cert) { delete cert; }
std::vector<SSLCertificate*> certs_;
// KT_LAST is intended for vector declarations and loops over all key types;
// it does not represent any key type in itself.
// KT_DEFAULT is used as the default KeyType for KeyParams.
static const int kRsaDefaultModSize = 1024;
static const int kRsaDefaultExponent = 0x10001; // = 2^16+1 = 65537
static const int kRsaMinModSize = 1024;
static const int kRsaMaxModSize = 8192;
// Certificate default validity lifetime.
static const int kDefaultCertificateLifetimeInSeconds =
60 * 60 * 24 * 30; // 30 days
// Certificate validity window.
// This is to compensate for slightly incorrect system clocks.
static const int kCertificateWindowInSeconds = -60 * 60 * 24;
struct RSAParams {
unsigned int mod_size;
unsigned int pub_exp;
enum ECCurve { EC_NIST_P256, /* EC_FANCY, */ EC_LAST };
class KeyParams {
// Generate a KeyParams object from a simple KeyType, using default params.
explicit KeyParams(KeyType key_type = KT_DEFAULT);
// Generate a a KeyParams for RSA with explicit parameters.
static KeyParams RSA(int mod_size = kRsaDefaultModSize,
int pub_exp = kRsaDefaultExponent);
// Generate a a KeyParams for ECDSA specifying the curve.
static KeyParams ECDSA(ECCurve curve = EC_NIST_P256);
// Check validity of a KeyParams object. Since the factory functions have
// no way of returning errors, this function can be called after creation
// to make sure the parameters are OK.
bool IsValid() const;
RSAParams rsa_params() const;
ECCurve ec_curve() const;
KeyType type() const { return type_; }
KeyType type_;
union {
RSAParams rsa;
ECCurve curve;
} params_;
// TODO(hbos): Remove once rtc::KeyType (to be modified) and
// blink::WebRTCKeyType (to be landed) match. By using this function in Chromium
// appropriately we can change KeyType enum -> class without breaking Chromium.
KeyType IntKeyTypeFamilyToKeyType(int key_type_family);
// Parameters for generating a certificate. If |common_name| is non-empty, it
// will be used for the certificate's subject and issuer name, otherwise a
// random string will be used.
struct SSLIdentityParams {
std::string common_name;
time_t not_before; // Absolute time since epoch in seconds.
time_t not_after; // Absolute time since epoch in seconds.
KeyParams key_params;
// Our identity in an SSL negotiation: a keypair and certificate (both
// with the same public key).
// This too is pretty much immutable once created.
class SSLIdentity {
// Generates an identity (keypair and self-signed certificate). If
// |common_name| is non-empty, it will be used for the certificate's subject
// and issuer name, otherwise a random string will be used. The key type and
// parameters are defined in |key_param|. The certificate's lifetime in
// seconds from the current time is defined in |certificate_lifetime|; it
// should be a non-negative number.
// Returns null on failure.
// Caller is responsible for freeing the returned object.
static SSLIdentity* GenerateWithExpiration(const std::string& common_name,
const KeyParams& key_param,
time_t certificate_lifetime);
static SSLIdentity* Generate(const std::string& common_name,
const KeyParams& key_param);
static SSLIdentity* Generate(const std::string& common_name,
KeyType key_type);
// Generates an identity with the specified validity period.
// TODO(torbjorng): Now that Generate() accepts relevant params, make tests
// use that instead of this function.
static SSLIdentity* GenerateForTest(const SSLIdentityParams& params);
// Construct an identity from a private key and a certificate.
static SSLIdentity* FromPEMStrings(const std::string& private_key,
const std::string& certificate);
virtual ~SSLIdentity() {}
// Returns a new SSLIdentity object instance wrapping the same
// identity information.
// Caller is responsible for freeing the returned object.
// TODO(hbos,torbjorng): Rename to a less confusing name.
virtual SSLIdentity* GetReference() const = 0;
// Returns a temporary reference to the certificate.
virtual const SSLCertificate& certificate() const = 0;
virtual std::string PrivateKeyToPEMString() const = 0;
virtual std::string PublicKeyToPEMString() const = 0;
// Helpers for parsing converting between PEM and DER format.
static bool PemToDer(const std::string& pem_type,
const std::string& pem_string,
std::string* der);
static std::string DerToPem(const std::string& pem_type,
const unsigned char* data,
size_t length);
bool operator==(const SSLIdentity& a, const SSLIdentity& b);
bool operator!=(const SSLIdentity& a, const SSLIdentity& b);
// Convert from ASN1 time as restricted by RFC 5280 to seconds from 1970-01-01
// 00.00 ("epoch"). If the ASN1 time cannot be read, return -1. The data at
// |s| is not 0-terminated; its char count is defined by |length|.
int64_t ASN1TimeToSec(const unsigned char* s, size_t length, bool long_format);
extern const char kPemTypeCertificate[];
extern const char kPemTypeRsaPrivateKey[];
extern const char kPemTypeEcPrivateKey[];
} // namespace rtc