blob: 4271366a880c5b2aa9d91c1fa5bde435fda5c9af [file] [log] [blame]
// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "verify_signed_data.h"
#include <openssl/bytestring.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>
#include "cert_errors.h"
#include "input.h"
#include "parse_values.h"
#include "parser.h"
#include "signature_algorithm.h"
#include "signature_verify_cache.h"
namespace bssl {
namespace {
bool SHA256UpdateWithLengthPrefixedData(SHA256_CTX *s_ctx, const uint8_t *data,
uint64_t length) {
return (SHA256_Update(s_ctx, reinterpret_cast<uint8_t *>(&length),
sizeof(length)) &&
SHA256_Update(s_ctx, data, length));
}
// Increase to make incompatible changes in the computation of the
// cache key.
constexpr uint32_t VerifyCacheKeyVersion = 1;
std::string SignatureVerifyCacheKey(std::string_view algorithm_name,
const der::Input &signed_data,
const der::Input &signature_value_bytes,
EVP_PKEY *public_key) {
SHA256_CTX s_ctx;
bssl::ScopedCBB public_key_cbb;
uint8_t digest[SHA256_DIGEST_LENGTH];
uint32_t version = VerifyCacheKeyVersion;
if (CBB_init(public_key_cbb.get(), 128) &&
EVP_marshal_public_key(public_key_cbb.get(), public_key) &&
SHA256_Init(&s_ctx) &&
SHA256_Update(&s_ctx, reinterpret_cast<uint8_t *>(&version),
sizeof(version)) &&
SHA256UpdateWithLengthPrefixedData(
&s_ctx, reinterpret_cast<const uint8_t *>(algorithm_name.data()),
algorithm_name.length()) &&
SHA256UpdateWithLengthPrefixedData(&s_ctx, CBB_data(public_key_cbb.get()),
CBB_len(public_key_cbb.get())) &&
SHA256UpdateWithLengthPrefixedData(&s_ctx,
signature_value_bytes.UnsafeData(),
signature_value_bytes.Length()) &&
SHA256UpdateWithLengthPrefixedData(&s_ctx, signed_data.UnsafeData(),
signed_data.Length()) &&
SHA256_Final(digest, &s_ctx)) {
return std::string(reinterpret_cast<char *>(digest), sizeof(digest));
}
return std::string();
}
// Place an instance of this class on the call stack to automatically clear
// the OpenSSL error stack on function exit.
// TODO(crbug.com/boringssl/38): Remove this when the library is more robust to
// leaving things in the error queue.
class OpenSSLErrStackTracer {
public:
~OpenSSLErrStackTracer() { ERR_clear_error(); };
};
} // namespace
// Parses an RSA public key or EC public key from SPKI to an EVP_PKEY. Returns
// true on success.
//
// This function only recognizes the "pk-rsa" (rsaEncryption) flavor of RSA
// public key from RFC 5912.
//
// pk-rsa PUBLIC-KEY ::= {
// IDENTIFIER rsaEncryption
// KEY RSAPublicKey
// PARAMS TYPE NULL ARE absent
// -- Private key format not in this module --
// CERT-KEY-USAGE {digitalSignature, nonRepudiation,
// keyEncipherment, dataEncipherment, keyCertSign, cRLSign}
// }
//
// COMPATIBILITY NOTE: RFC 5912 and RFC 3279 are in disagreement on the value
// of parameters for rsaEncryption. Whereas RFC 5912 says they must be absent,
// RFC 3279 says they must be NULL:
//
// The rsaEncryption OID is intended to be used in the algorithm field
// of a value of type AlgorithmIdentifier. The parameters field MUST
// have ASN.1 type NULL for this algorithm identifier.
//
// Following RFC 3279 in this case.
//
// In the case of parsing EC keys, RFC 5912 describes all the ECDSA
// signature algorithms as requiring a public key of type "pk-ec":
//
// pk-ec PUBLIC-KEY ::= {
// IDENTIFIER id-ecPublicKey
// KEY ECPoint
// PARAMS TYPE ECParameters ARE required
// -- Private key format not in this module --
// CERT-KEY-USAGE { digitalSignature, nonRepudiation, keyAgreement,
// keyCertSign, cRLSign }
// }
//
// Moreover RFC 5912 stipulates what curves are allowed. The ECParameters
// MUST NOT use an implicitCurve or specificCurve for PKIX:
//
// ECParameters ::= CHOICE {
// namedCurve CURVE.&id({NamedCurve})
// -- implicitCurve NULL
// -- implicitCurve MUST NOT be used in PKIX
// -- specifiedCurve SpecifiedCurve
// -- specifiedCurve MUST NOT be used in PKIX
// -- Details for specifiedCurve can be found in [X9.62]
// -- Any future additions to this CHOICE should be coordinated
// -- with ANSI X.9.
// }
// -- If you need to be able to decode ANSI X.9 parameter structures,
// -- uncomment the implicitCurve and specifiedCurve above, and also
// -- uncomment the following:
// --(WITH COMPONENTS {namedCurve PRESENT})
//
// The namedCurves are extensible. The ones described by RFC 5912 are:
//
// NamedCurve CURVE ::= {
// { ID secp192r1 } | { ID sect163k1 } | { ID sect163r2 } |
// { ID secp224r1 } | { ID sect233k1 } | { ID sect233r1 } |
// { ID secp256r1 } | { ID sect283k1 } | { ID sect283r1 } |
// { ID secp384r1 } | { ID sect409k1 } | { ID sect409r1 } |
// { ID secp521r1 } | { ID sect571k1 } | { ID sect571r1 },
// ... -- Extensible
// }
bool ParsePublicKey(const der::Input &public_key_spki,
bssl::UniquePtr<EVP_PKEY> *public_key) {
// Parse the SPKI to an EVP_PKEY.
OpenSSLErrStackTracer err_tracer;
CBS cbs;
CBS_init(&cbs, public_key_spki.UnsafeData(), public_key_spki.Length());
public_key->reset(EVP_parse_public_key(&cbs));
if (!*public_key || CBS_len(&cbs) != 0) {
public_key->reset();
return false;
}
return true;
}
bool VerifySignedData(SignatureAlgorithm algorithm,
const der::Input &signed_data,
const der::BitString &signature_value,
EVP_PKEY *public_key, SignatureVerifyCache *cache) {
int expected_pkey_id = 1;
const EVP_MD *digest = nullptr;
bool is_rsa_pss = false;
std::string_view cache_algorithm_name;
switch (algorithm) {
case SignatureAlgorithm::kRsaPkcs1Sha1:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha1();
cache_algorithm_name = "RsaPkcs1Sha1";
break;
case SignatureAlgorithm::kRsaPkcs1Sha256:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha256();
cache_algorithm_name = "RsaPkcs1Sha256";
break;
case SignatureAlgorithm::kRsaPkcs1Sha384:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha384();
cache_algorithm_name = "RsaPkcs1Sha384";
break;
case SignatureAlgorithm::kRsaPkcs1Sha512:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha512();
cache_algorithm_name = "RsaPkcs1Sha512";
break;
case SignatureAlgorithm::kEcdsaSha1:
expected_pkey_id = EVP_PKEY_EC;
digest = EVP_sha1();
cache_algorithm_name = "EcdsaSha1";
break;
case SignatureAlgorithm::kEcdsaSha256:
expected_pkey_id = EVP_PKEY_EC;
digest = EVP_sha256();
cache_algorithm_name = "EcdsaSha256";
break;
case SignatureAlgorithm::kEcdsaSha384:
expected_pkey_id = EVP_PKEY_EC;
digest = EVP_sha384();
cache_algorithm_name = "EcdsaSha384";
break;
case SignatureAlgorithm::kEcdsaSha512:
expected_pkey_id = EVP_PKEY_EC;
digest = EVP_sha512();
cache_algorithm_name = "EcdsaSha512";
break;
case SignatureAlgorithm::kRsaPssSha256:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha256();
cache_algorithm_name = "RsaPssSha256";
is_rsa_pss = true;
break;
case SignatureAlgorithm::kRsaPssSha384:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha384();
cache_algorithm_name = "RsaPssSha384";
is_rsa_pss = true;
break;
case SignatureAlgorithm::kRsaPssSha512:
expected_pkey_id = EVP_PKEY_RSA;
digest = EVP_sha512();
cache_algorithm_name = "RsaPssSha512";
is_rsa_pss = true;
break;
}
if (expected_pkey_id != EVP_PKEY_id(public_key)) {
return false;
}
// For the supported algorithms the signature value must be a whole
// number of bytes.
if (signature_value.unused_bits() != 0) {
return false;
}
const der::Input &signature_value_bytes = signature_value.bytes();
std::string cache_key;
if (cache) {
cache_key = SignatureVerifyCacheKey(cache_algorithm_name, signed_data,
signature_value_bytes, public_key);
if (!cache_key.empty()) {
switch (cache->Check(cache_key)) {
case SignatureVerifyCache::Value::kValid:
return true;
case SignatureVerifyCache::Value::kInvalid:
return false;
case SignatureVerifyCache::Value::kUnknown:
break;
}
}
}
OpenSSLErrStackTracer err_tracer;
bssl::ScopedEVP_MD_CTX ctx;
EVP_PKEY_CTX *pctx = nullptr; // Owned by |ctx|.
if (!EVP_DigestVerifyInit(ctx.get(), &pctx, digest, nullptr, public_key)) {
return false;
}
if (is_rsa_pss) {
// All supported RSASSA-PSS algorithms match signing and MGF-1 digest. They
// also use the digest length as the salt length, which is specified with -1
// in OpenSSL's API.
if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) ||
!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) {
return false;
}
}
if (!EVP_DigestVerifyUpdate(ctx.get(), signed_data.UnsafeData(),
signed_data.Length())) {
return false;
}
bool ret =
1 == EVP_DigestVerifyFinal(ctx.get(), signature_value_bytes.UnsafeData(),
signature_value_bytes.Length());
if (!cache_key.empty()) {
cache->Store(cache_key, ret ? SignatureVerifyCache::Value::kValid
: SignatureVerifyCache::Value::kInvalid);
}
return ret;
}
bool VerifySignedData(SignatureAlgorithm algorithm,
const der::Input &signed_data,
const der::BitString &signature_value,
const der::Input &public_key_spki,
SignatureVerifyCache *cache) {
bssl::UniquePtr<EVP_PKEY> public_key;
if (!ParsePublicKey(public_key_spki, &public_key)) {
return false;
}
return VerifySignedData(algorithm, signed_data, signature_value,
public_key.get(), cache);
}
} // namespace bssl