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// 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 "signature_algorithm.h"
#include <openssl/bytestring.h>
#include <openssl/digest.h>
#include "input.h"
#include "parse_values.h"
#include "parser.h"
namespace bssl {
namespace {
// From RFC 5912:
//
// sha1WithRSAEncryption OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
// pkcs-1(1) 5 }
//
// In dotted notation: 1.2.840.113549.1.1.5
const uint8_t kOidSha1WithRsaEncryption[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x05};
// sha1WithRSASignature is a deprecated equivalent of
// sha1WithRSAEncryption.
//
// It originates from the NIST Open Systems Environment (OSE)
// Implementor's Workshop (OIW).
//
// It is supported for compatibility with Microsoft's certificate APIs and
// tools, particularly makecert.exe, which default(ed/s) to this OID for SHA-1.
//
// See also: https://bugzilla.mozilla.org/show_bug.cgi?id=1042479
//
// In dotted notation: 1.3.14.3.2.29
const uint8_t kOidSha1WithRsaSignature[] = {0x2b, 0x0e, 0x03, 0x02, 0x1d};
// From RFC 5912:
//
// pkcs-1 OBJECT IDENTIFIER ::=
// { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }
// From RFC 5912:
//
// sha256WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 11 }
//
// In dotted notation: 1.2.840.113549.1.1.11
const uint8_t kOidSha256WithRsaEncryption[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x0b};
// From RFC 5912:
//
// sha384WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 12 }
//
// In dotted notation: 1.2.840.113549.1.1.11
const uint8_t kOidSha384WithRsaEncryption[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x0c};
// From RFC 5912:
//
// sha512WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 13 }
//
// In dotted notation: 1.2.840.113549.1.1.13
const uint8_t kOidSha512WithRsaEncryption[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x0d};
// From RFC 5912:
//
// ecdsa-with-SHA1 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045)
// signatures(4) 1 }
//
// In dotted notation: 1.2.840.10045.4.1
const uint8_t kOidEcdsaWithSha1[] = {0x2a, 0x86, 0x48, 0xce, 0x3d, 0x04, 0x01};
// From RFC 5912:
//
// ecdsa-with-SHA256 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4)
// ecdsa-with-SHA2(3) 2 }
//
// In dotted notation: 1.2.840.10045.4.3.2
const uint8_t kOidEcdsaWithSha256[] = {0x2a, 0x86, 0x48, 0xce,
0x3d, 0x04, 0x03, 0x02};
// From RFC 5912:
//
// ecdsa-with-SHA384 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4)
// ecdsa-with-SHA2(3) 3 }
//
// In dotted notation: 1.2.840.10045.4.3.3
const uint8_t kOidEcdsaWithSha384[] = {0x2a, 0x86, 0x48, 0xce,
0x3d, 0x04, 0x03, 0x03};
// From RFC 5912:
//
// ecdsa-with-SHA512 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4)
// ecdsa-with-SHA2(3) 4 }
//
// In dotted notation: 1.2.840.10045.4.3.4
const uint8_t kOidEcdsaWithSha512[] = {0x2a, 0x86, 0x48, 0xce,
0x3d, 0x04, 0x03, 0x04};
// From RFC 5912:
//
// id-RSASSA-PSS OBJECT IDENTIFIER ::= { pkcs-1 10 }
//
// In dotted notation: 1.2.840.113549.1.1.10
const uint8_t kOidRsaSsaPss[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x0a};
// From RFC 5912:
//
// id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 }
//
// In dotted notation: 1.2.840.113549.1.1.8
const uint8_t kOidMgf1[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
0x0d, 0x01, 0x01, 0x08};
// Returns true if the entirety of the input is a NULL value.
[[nodiscard]] bool IsNull(der::Input input) {
der::Parser parser(input);
der::Input null_value;
if (!parser.ReadTag(CBS_ASN1_NULL, &null_value)) {
return false;
}
// NULL values are TLV encoded; the value is expected to be empty.
if (!null_value.empty()) {
return false;
}
// By definition of this function, the entire input must be a NULL.
return !parser.HasMore();
}
[[nodiscard]] bool IsNullOrEmpty(der::Input input) {
return IsNull(input) || input.empty();
}
// Parses a MaskGenAlgorithm as defined by RFC 5912:
//
// MaskGenAlgorithm ::= AlgorithmIdentifier{ALGORITHM,
// {PKCS1MGFAlgorithms}}
//
// mgf1SHA1 MaskGenAlgorithm ::= {
// algorithm id-mgf1,
// parameters HashAlgorithm : sha1Identifier
// }
//
// --
// -- Define the set of mask generation functions
// --
// -- If the identifier is id-mgf1, any of the listed hash
// -- algorithms may be used.
// --
//
// PKCS1MGFAlgorithms ALGORITHM ::= {
// { IDENTIFIER id-mgf1 PARAMS TYPE HashAlgorithm ARE required },
// ...
// }
//
// Note that the possible mask gen algorithms is extensible. However at present
// the only function supported is MGF1, as that is the singular mask gen
// function defined by RFC 4055 / RFC 5912.
[[nodiscard]] bool ParseMaskGenAlgorithm(const der::Input input,
DigestAlgorithm *mgf1_hash) {
der::Input oid;
der::Input params;
if (!ParseAlgorithmIdentifier(input, &oid, &params)) {
return false;
}
// MGF1 is the only supported mask generation algorithm.
if (oid != der::Input(kOidMgf1)) {
return false;
}
return ParseHashAlgorithm(params, mgf1_hash);
}
// Parses the parameters for an RSASSA-PSS signature algorithm, as defined by
// RFC 5912:
//
// sa-rsaSSA-PSS SIGNATURE-ALGORITHM ::= {
// IDENTIFIER id-RSASSA-PSS
// PARAMS TYPE RSASSA-PSS-params ARE required
// HASHES { mda-sha1 | mda-sha224 | mda-sha256 | mda-sha384
// | mda-sha512 }
// PUBLIC-KEYS { pk-rsa | pk-rsaSSA-PSS }
// SMIME-CAPS { IDENTIFIED BY id-RSASSA-PSS }
// }
//
// RSASSA-PSS-params ::= SEQUENCE {
// hashAlgorithm [0] HashAlgorithm DEFAULT sha1Identifier,
// maskGenAlgorithm [1] MaskGenAlgorithm DEFAULT mgf1SHA1,
// saltLength [2] INTEGER DEFAULT 20,
// trailerField [3] INTEGER DEFAULT 1
// }
//
// Which is to say the parameters MUST be present, and of type
// RSASSA-PSS-params. Additionally, we only support the RSA-PSS parameter
// combinations representable by TLS 1.3 (RFC 8446).
//
// Note also that DER encoding (ITU-T X.690 section 11.5) prohibits
// specifying default values explicitly. The parameter should instead be
// omitted to indicate a default value.
std::optional<SignatureAlgorithm> ParseRsaPss(der::Input params) {
der::Parser parser(params);
der::Parser params_parser;
if (!parser.ReadSequence(&params_parser)) {
return std::nullopt;
}
// There shouldn't be anything after the sequence (by definition the
// parameters is a single sequence).
if (parser.HasMore()) {
return std::nullopt;
}
// The default values for hashAlgorithm, maskGenAlgorithm, and saltLength
// correspond to SHA-1, which we do not support with RSA-PSS, so treat them as
// required fields. Explicitly-specified defaults will be rejected later, when
// we limit combinations. Additionally, as the trailerField is required to be
// the default, we simply ignore it and reject it as any other trailing data.
//
// hashAlgorithm [0] HashAlgorithm DEFAULT sha1Identifier,
// maskGenAlgorithm [1] MaskGenAlgorithm DEFAULT mgf1SHA1,
// saltLength [2] INTEGER DEFAULT 20,
// trailerField [3] INTEGER DEFAULT 1
der::Input field;
DigestAlgorithm hash, mgf1_hash;
der::Parser salt_length_parser;
uint64_t salt_length;
if (!params_parser.ReadTag(
CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0, &field) ||
!ParseHashAlgorithm(field, &hash) ||
!params_parser.ReadTag(
CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1, &field) ||
!ParseMaskGenAlgorithm(field, &mgf1_hash) ||
!params_parser.ReadConstructed(
CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 2,
&salt_length_parser) ||
!salt_length_parser.ReadUint64(&salt_length) ||
salt_length_parser.HasMore() || params_parser.HasMore()) {
return std::nullopt;
}
// Only combinations of RSASSA-PSS-params specified by TLS 1.3 (RFC 8446) are
// supported.
if (hash != mgf1_hash) {
return std::nullopt; // TLS 1.3 always matches MGF-1 and message hash.
}
if (hash == DigestAlgorithm::Sha256 && salt_length == 32) {
return SignatureAlgorithm::kRsaPssSha256;
}
if (hash == DigestAlgorithm::Sha384 && salt_length == 48) {
return SignatureAlgorithm::kRsaPssSha384;
}
if (hash == DigestAlgorithm::Sha512 && salt_length == 64) {
return SignatureAlgorithm::kRsaPssSha512;
}
return std::nullopt;
}
} // namespace
[[nodiscard]] bool ParseAlgorithmIdentifier(der::Input input,
der::Input *algorithm,
der::Input *parameters) {
der::Parser parser(input);
der::Parser algorithm_identifier_parser;
if (!parser.ReadSequence(&algorithm_identifier_parser)) {
return false;
}
// There shouldn't be anything after the sequence. This is by definition,
// as the input to this function is expected to be a single
// AlgorithmIdentifier.
if (parser.HasMore()) {
return false;
}
if (!algorithm_identifier_parser.ReadTag(CBS_ASN1_OBJECT, algorithm)) {
return false;
}
// Read the optional parameters to a der::Input. The parameters can be at
// most one TLV (for instance NULL or a sequence).
//
// Note that nothing is allowed after the single optional "parameters" TLV.
// This is because RFC 5912's notation for AlgorithmIdentifier doesn't
// explicitly list an extension point after "parameters".
*parameters = der::Input();
if (algorithm_identifier_parser.HasMore() &&
!algorithm_identifier_parser.ReadRawTLV(parameters)) {
return false;
}
return !algorithm_identifier_parser.HasMore();
}
[[nodiscard]] bool ParseHashAlgorithm(der::Input input, DigestAlgorithm *out) {
CBS cbs;
CBS_init(&cbs, input.data(), input.size());
const EVP_MD *md = EVP_parse_digest_algorithm(&cbs);
if (md == EVP_sha1()) {
*out = DigestAlgorithm::Sha1;
} else if (md == EVP_sha256()) {
*out = DigestAlgorithm::Sha256;
} else if (md == EVP_sha384()) {
*out = DigestAlgorithm::Sha384;
} else if (md == EVP_sha512()) {
*out = DigestAlgorithm::Sha512;
} else {
// TODO(eroman): Support MD2, MD4, MD5 for completeness?
// Unsupported digest algorithm.
return false;
}
return true;
}
std::optional<SignatureAlgorithm> ParseSignatureAlgorithm(
der::Input algorithm_identifier) {
der::Input oid;
der::Input params;
if (!ParseAlgorithmIdentifier(algorithm_identifier, &oid, &params)) {
return std::nullopt;
}
// TODO(eroman): Each OID is tested for equality in order, which is not
// particularly efficient.
// RFC 5912 requires that the parameters for RSA PKCS#1 v1.5 algorithms be
// NULL ("PARAMS TYPE NULL ARE required"), however an empty parameter is also
// allowed for compatibility with non-compliant OCSP responders.
//
// TODO(svaldez): Add warning about non-strict parsing.
if (oid == der::Input(kOidSha1WithRsaEncryption) && IsNullOrEmpty(params)) {
return SignatureAlgorithm::kRsaPkcs1Sha1;
}
if (oid == der::Input(kOidSha256WithRsaEncryption) && IsNullOrEmpty(params)) {
return SignatureAlgorithm::kRsaPkcs1Sha256;
}
if (oid == der::Input(kOidSha384WithRsaEncryption) && IsNullOrEmpty(params)) {
return SignatureAlgorithm::kRsaPkcs1Sha384;
}
if (oid == der::Input(kOidSha512WithRsaEncryption) && IsNullOrEmpty(params)) {
return SignatureAlgorithm::kRsaPkcs1Sha512;
}
if (oid == der::Input(kOidSha1WithRsaSignature) && IsNullOrEmpty(params)) {
return SignatureAlgorithm::kRsaPkcs1Sha1;
}
// RFC 5912 requires that the parameters for ECDSA algorithms be absent
// ("PARAMS TYPE NULL ARE absent"):
if (oid == der::Input(kOidEcdsaWithSha1) && params.empty()) {
return SignatureAlgorithm::kEcdsaSha1;
}
if (oid == der::Input(kOidEcdsaWithSha256) && params.empty()) {
return SignatureAlgorithm::kEcdsaSha256;
}
if (oid == der::Input(kOidEcdsaWithSha384) && params.empty()) {
return SignatureAlgorithm::kEcdsaSha384;
}
if (oid == der::Input(kOidEcdsaWithSha512) && params.empty()) {
return SignatureAlgorithm::kEcdsaSha512;
}
if (oid == der::Input(kOidRsaSsaPss)) {
return ParseRsaPss(params);
}
// Unknown signature algorithm.
return std::nullopt;
}
std::optional<DigestAlgorithm> GetTlsServerEndpointDigestAlgorithm(
SignatureAlgorithm alg) {
// See RFC 5929, section 4.1. RFC 5929 breaks the signature algorithm
// abstraction by trying to extract individual digest algorithms. (While
// common, this is not a universal property of signature algorithms.) We
// implement this within the library, so callers do not need to condition over
// all algorithms.
switch (alg) {
// If the single digest algorithm is SHA-1, use SHA-256.
case SignatureAlgorithm::kRsaPkcs1Sha1:
case SignatureAlgorithm::kEcdsaSha1:
return DigestAlgorithm::Sha256;
case SignatureAlgorithm::kRsaPkcs1Sha256:
case SignatureAlgorithm::kEcdsaSha256:
return DigestAlgorithm::Sha256;
case SignatureAlgorithm::kRsaPkcs1Sha384:
case SignatureAlgorithm::kEcdsaSha384:
return DigestAlgorithm::Sha384;
case SignatureAlgorithm::kRsaPkcs1Sha512:
case SignatureAlgorithm::kEcdsaSha512:
return DigestAlgorithm::Sha512;
// It is ambiguous whether hash-matching RSASSA-PSS instantiations count as
// using one or multiple digests, but the corresponding digest is the only
// reasonable interpretation.
case SignatureAlgorithm::kRsaPssSha256:
return DigestAlgorithm::Sha256;
case SignatureAlgorithm::kRsaPssSha384:
return DigestAlgorithm::Sha384;
case SignatureAlgorithm::kRsaPssSha512:
return DigestAlgorithm::Sha512;
}
return std::nullopt;
}
} // namespace bssl