/*
* Copyright 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "rsa_operation.h"
#include <limits.h>
#include <new>
#include <openssl/err.h>
#include <keymaster/logger.h>
#include "openssl_err.h"
#include "openssl_utils.h"
#include "rsa_key.h"
namespace keymaster {
const size_t kPssOverhead = 2;
const size_t kMinPssSaltSize = 20;
// Overhead for PKCS#1 v1.5 signature padding of undigested messages. Digested messages have
// additional overhead, for the digest algorithmIdentifier required by PKCS#1.
const size_t kPkcs1UndigestedSignaturePaddingOverhead = 11;
/* static */
EVP_PKEY* RsaOperationFactory::GetRsaKey(const Key& key, keymaster_error_t* error) {
const RsaKey* rsa_key = static_cast<const RsaKey*>(&key);
assert(rsa_key);
if (!rsa_key || !rsa_key->key()) {
*error = KM_ERROR_UNKNOWN_ERROR;
return nullptr;
}
UniquePtr<EVP_PKEY, EVP_PKEY_Delete> pkey(EVP_PKEY_new());
if (!rsa_key->InternalToEvp(pkey.get())) {
*error = KM_ERROR_UNKNOWN_ERROR;
return nullptr;
}
return pkey.release();
}
static const keymaster_digest_t supported_digests[] = {
KM_DIGEST_NONE, KM_DIGEST_MD5, KM_DIGEST_SHA1, KM_DIGEST_SHA_2_224,
KM_DIGEST_SHA_2_256, KM_DIGEST_SHA_2_384, KM_DIGEST_SHA_2_512};
const keymaster_digest_t* RsaOperationFactory::SupportedDigests(size_t* digest_count) const {
*digest_count = array_length(supported_digests);
return supported_digests;
}
RsaOperation* RsaOperationFactory::CreateRsaOperation(const Key& key,
const AuthorizationSet& begin_params,
keymaster_error_t* error) {
keymaster_padding_t padding;
if (!GetAndValidatePadding(begin_params, key, &padding, error))
return nullptr;
bool require_digest = (purpose() == KM_PURPOSE_SIGN || purpose() == KM_PURPOSE_VERIFY ||
padding == KM_PAD_RSA_OAEP);
keymaster_digest_t digest = KM_DIGEST_NONE;
if (require_digest && !GetAndValidateDigest(begin_params, key, &digest, error))
return nullptr;
UniquePtr<EVP_PKEY, EVP_PKEY_Delete> rsa(GetRsaKey(key, error));
if (!rsa.get())
return nullptr;
RsaOperation* op = InstantiateOperation(digest, padding, rsa.release());
if (!op)
*error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return op;
}
static const keymaster_padding_t supported_sig_padding[] = {KM_PAD_NONE, KM_PAD_RSA_PKCS1_1_5_SIGN,
KM_PAD_RSA_PSS};
const keymaster_padding_t*
RsaDigestingOperationFactory::SupportedPaddingModes(size_t* padding_mode_count) const {
*padding_mode_count = array_length(supported_sig_padding);
return supported_sig_padding;
}
RsaOperation* RsaCryptingOperationFactory::CreateRsaOperation(const Key& key,
const AuthorizationSet& begin_params,
keymaster_error_t* error) {
UniquePtr<RsaOperation> op(RsaOperationFactory::CreateRsaOperation(key, begin_params, error));
if (op.get()) {
switch (op->padding()) {
case KM_PAD_NONE:
case KM_PAD_RSA_PKCS1_1_5_ENCRYPT:
if (op->digest() != KM_DIGEST_NONE) {
*error = KM_ERROR_INCOMPATIBLE_DIGEST;
return nullptr;
}
break;
case KM_PAD_RSA_OAEP:
if (op->digest() == KM_DIGEST_NONE) {
*error = KM_ERROR_INCOMPATIBLE_DIGEST;
return nullptr;
}
break;
default:
*error = KM_ERROR_UNSUPPORTED_PADDING_MODE;
return nullptr;
}
}
return op.release();
}
static const keymaster_padding_t supported_crypt_padding[] = {KM_PAD_NONE, KM_PAD_RSA_OAEP,
KM_PAD_RSA_PKCS1_1_5_ENCRYPT};
const keymaster_padding_t*
RsaCryptingOperationFactory::SupportedPaddingModes(size_t* padding_mode_count) const {
*padding_mode_count = array_length(supported_crypt_padding);
return supported_crypt_padding;
}
RsaOperation::~RsaOperation() {
if (rsa_key_ != NULL)
EVP_PKEY_free(rsa_key_);
}
keymaster_error_t RsaOperation::Begin(const AuthorizationSet& /* input_params */,
AuthorizationSet* /* output_params */) {
return InitDigest();
}
keymaster_error_t RsaOperation::Update(const AuthorizationSet& /* additional_params */,
const Buffer& input, AuthorizationSet* /* output_params */,
Buffer* /* output */, size_t* input_consumed) {
assert(input_consumed);
switch (purpose()) {
default:
return KM_ERROR_UNIMPLEMENTED;
case KM_PURPOSE_SIGN:
case KM_PURPOSE_VERIFY:
case KM_PURPOSE_ENCRYPT:
case KM_PURPOSE_DECRYPT:
return StoreData(input, input_consumed);
}
}
keymaster_error_t RsaOperation::StoreData(const Buffer& input, size_t* input_consumed) {
assert(input_consumed);
if (!data_.reserve(EVP_PKEY_size(rsa_key_)))
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
// If the write fails, it's because input length exceeds key size.
if (!data_.write(input.peek_read(), input.available_read())) {
LOG_E("Input too long: cannot operate on %u bytes of data with %u-byte RSA key",
input.available_read() + data_.available_read(), EVP_PKEY_size(rsa_key_));
return KM_ERROR_INVALID_INPUT_LENGTH;
}
*input_consumed = input.available_read();
return KM_ERROR_OK;
}
keymaster_error_t RsaOperation::SetRsaPaddingInEvpContext(EVP_PKEY_CTX* pkey_ctx) {
keymaster_error_t error;
int openssl_padding = GetOpensslPadding(&error);
if (error != KM_ERROR_OK)
return error;
if (EVP_PKEY_CTX_set_rsa_padding(pkey_ctx, openssl_padding) <= 0)
return TranslateLastOpenSslError();
return KM_ERROR_OK;
}
keymaster_error_t RsaOperation::InitDigest() {
if (digest_ == KM_DIGEST_NONE) {
if (require_digest())
return KM_ERROR_INCOMPATIBLE_DIGEST;
return KM_ERROR_OK;
}
switch (digest_) {
case KM_DIGEST_NONE:
return KM_ERROR_OK;
case KM_DIGEST_MD5:
digest_algorithm_ = EVP_md5();
return KM_ERROR_OK;
case KM_DIGEST_SHA1:
digest_algorithm_ = EVP_sha1();
return KM_ERROR_OK;
case KM_DIGEST_SHA_2_224:
digest_algorithm_ = EVP_sha224();
return KM_ERROR_OK;
case KM_DIGEST_SHA_2_256:
digest_algorithm_ = EVP_sha256();
return KM_ERROR_OK;
case KM_DIGEST_SHA_2_384:
digest_algorithm_ = EVP_sha384();
return KM_ERROR_OK;
case KM_DIGEST_SHA_2_512:
digest_algorithm_ = EVP_sha512();
return KM_ERROR_OK;
default:
return KM_ERROR_UNSUPPORTED_DIGEST;
}
}
RsaDigestingOperation::RsaDigestingOperation(keymaster_purpose_t purpose, keymaster_digest_t digest,
keymaster_padding_t padding, EVP_PKEY* key)
: RsaOperation(purpose, digest, padding, key) {
EVP_MD_CTX_init(&digest_ctx_);
}
RsaDigestingOperation::~RsaDigestingOperation() {
EVP_MD_CTX_cleanup(&digest_ctx_);
}
int RsaDigestingOperation::GetOpensslPadding(keymaster_error_t* error) {
*error = KM_ERROR_OK;
switch (padding_) {
case KM_PAD_NONE:
return RSA_NO_PADDING;
case KM_PAD_RSA_PKCS1_1_5_SIGN:
return RSA_PKCS1_PADDING;
case KM_PAD_RSA_PSS:
if (digest_ == KM_DIGEST_NONE) {
*error = KM_ERROR_INCOMPATIBLE_PADDING_MODE;
return -1;
}
if (EVP_MD_size(digest_algorithm_) + kPssOverhead + kMinPssSaltSize >
(size_t)EVP_PKEY_size(rsa_key_)) {
LOG_E("Input too long: %d-byte digest cannot be used with %d-byte RSA key in PSS "
"padding mode",
EVP_MD_size(digest_algorithm_), EVP_PKEY_size(rsa_key_));
*error = KM_ERROR_INCOMPATIBLE_DIGEST;
return -1;
}
return RSA_PKCS1_PSS_PADDING;
default:
return -1;
}
}
keymaster_error_t RsaSignOperation::Begin(const AuthorizationSet& input_params,
AuthorizationSet* output_params) {
keymaster_error_t error = RsaDigestingOperation::Begin(input_params, output_params);
if (error != KM_ERROR_OK)
return error;
if (digest_ == KM_DIGEST_NONE)
return KM_ERROR_OK;
EVP_PKEY_CTX* pkey_ctx;
if (EVP_DigestSignInit(&digest_ctx_, &pkey_ctx, digest_algorithm_, nullptr /* engine */,
rsa_key_) != 1)
return TranslateLastOpenSslError();
return SetRsaPaddingInEvpContext(pkey_ctx);
}
keymaster_error_t RsaSignOperation::Update(const AuthorizationSet& additional_params,
const Buffer& input, AuthorizationSet* output_params,
Buffer* output, size_t* input_consumed) {
if (digest_ == KM_DIGEST_NONE)
// Just buffer the data.
return RsaOperation::Update(additional_params, input, output_params, output,
input_consumed);
if (EVP_DigestSignUpdate(&digest_ctx_, input.peek_read(), input.available_read()) != 1)
return TranslateLastOpenSslError();
*input_consumed = input.available_read();
return KM_ERROR_OK;
}
keymaster_error_t RsaSignOperation::Finish(const AuthorizationSet& /* additional_params */,
const Buffer& /* signature */,
AuthorizationSet* /* output_params */, Buffer* output) {
assert(output);
if (digest_ == KM_DIGEST_NONE)
return SignUndigested(output);
else
return SignDigested(output);
}
static keymaster_error_t zero_pad_left(UniquePtr<uint8_t[]>* dest, size_t padded_len, Buffer& src) {
assert(padded_len > src.available_read());
dest->reset(new uint8_t[padded_len]);
if (!dest->get())
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
size_t padding_len = padded_len - src.available_read();
memset(dest->get(), 0, padding_len);
if (!src.read(dest->get() + padding_len, src.available_read()))
return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
keymaster_error_t RsaSignOperation::SignUndigested(Buffer* output) {
UniquePtr<RSA, RSA_Delete> rsa(EVP_PKEY_get1_RSA(const_cast<EVP_PKEY*>(rsa_key_)));
if (!rsa.get())
return TranslateLastOpenSslError();
if (!output->Reinitialize(RSA_size(rsa.get())))
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
size_t key_len = EVP_PKEY_size(rsa_key_);
int bytes_encrypted;
switch (padding_) {
case KM_PAD_NONE: {
const uint8_t* to_encrypt = data_.peek_read();
UniquePtr<uint8_t[]> zero_padded;
if (data_.available_read() > key_len) {
return KM_ERROR_INVALID_INPUT_LENGTH;
} else if (data_.available_read() < key_len) {
keymaster_error_t error = zero_pad_left(&zero_padded, key_len, data_);
if (error != KM_ERROR_OK)
return error;
to_encrypt = zero_padded.get();
}
bytes_encrypted = RSA_private_encrypt(key_len, to_encrypt, output->peek_write(), rsa.get(),
RSA_NO_PADDING);
break;
}
case KM_PAD_RSA_PKCS1_1_5_SIGN:
// Does PKCS1 padding without digesting even make sense? Dunno. We'll support it.
if (data_.available_read() + kPkcs1UndigestedSignaturePaddingOverhead > key_len) {
LOG_E("Input too long: cannot sign %u-byte message with PKCS1 padding with %u-bit key",
data_.available_read(), EVP_PKEY_size(rsa_key_) * 8);
return KM_ERROR_INVALID_INPUT_LENGTH;
}
bytes_encrypted = RSA_private_encrypt(data_.available_read(), data_.peek_read(),
output->peek_write(), rsa.get(), RSA_PKCS1_PADDING);
break;
default:
return KM_ERROR_UNSUPPORTED_PADDING_MODE;
}
if (bytes_encrypted <= 0)
return TranslateLastOpenSslError();
if (!output->advance_write(bytes_encrypted))
return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
keymaster_error_t RsaSignOperation::SignDigested(Buffer* output) {
size_t siglen;
if (EVP_DigestSignFinal(&digest_ctx_, nullptr /* signature */, &siglen) != 1)
return TranslateLastOpenSslError();
if (!output->Reinitialize(siglen))
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (EVP_DigestSignFinal(&digest_ctx_, output->peek_write(), &siglen) <= 0)
return TranslateLastOpenSslError();
if (!output->advance_write(siglen))
return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
keymaster_error_t RsaVerifyOperation::Begin(const AuthorizationSet& input_params,
AuthorizationSet* output_params) {
keymaster_error_t error = RsaDigestingOperation::Begin(input_params, output_params);
if (error != KM_ERROR_OK)
return error;
if (digest_ == KM_DIGEST_NONE)
return KM_ERROR_OK;
EVP_PKEY_CTX* pkey_ctx;
if (EVP_DigestVerifyInit(&digest_ctx_, &pkey_ctx, digest_algorithm_, NULL, rsa_key_) != 1)
return TranslateLastOpenSslError();
return SetRsaPaddingInEvpContext(pkey_ctx);
}
keymaster_error_t RsaVerifyOperation::Update(const AuthorizationSet& additional_params,
const Buffer& input, AuthorizationSet* output_params,
Buffer* output, size_t* input_consumed) {
if (digest_ == KM_DIGEST_NONE)
// Just buffer the data.
return RsaOperation::Update(additional_params, input, output_params, output,
input_consumed);
if (EVP_DigestVerifyUpdate(&digest_ctx_, input.peek_read(), input.available_read()) != 1)
return TranslateLastOpenSslError();
*input_consumed = input.available_read();
return KM_ERROR_OK;
}
keymaster_error_t RsaVerifyOperation::Finish(const AuthorizationSet& /* additional_params */,
const Buffer& signature,
AuthorizationSet* /* output_params */,
Buffer* /* output */) {
if (digest_ == KM_DIGEST_NONE)
return VerifyUndigested(signature);
else
return VerifyDigested(signature);
}
keymaster_error_t RsaVerifyOperation::VerifyUndigested(const Buffer& signature) {
UniquePtr<RSA, RSA_Delete> rsa(EVP_PKEY_get1_RSA(const_cast<EVP_PKEY*>(rsa_key_)));
if (!rsa.get())
return KM_ERROR_UNKNOWN_ERROR;
size_t key_len = RSA_size(rsa.get());
int openssl_padding;
switch (padding_) {
case KM_PAD_NONE:
if (data_.available_read() > key_len)
return KM_ERROR_INVALID_INPUT_LENGTH;
if (key_len != signature.available_read())
return KM_ERROR_VERIFICATION_FAILED;
openssl_padding = RSA_NO_PADDING;
break;
case KM_PAD_RSA_PKCS1_1_5_SIGN:
if (data_.available_read() + kPkcs1UndigestedSignaturePaddingOverhead > key_len) {
LOG_E("Input too long: cannot verify %u-byte message with PKCS1 padding && %u-bit key",
data_.available_read(), key_len * 8);
return KM_ERROR_INVALID_INPUT_LENGTH;
}
openssl_padding = RSA_PKCS1_PADDING;
break;
default:
return KM_ERROR_UNSUPPORTED_PADDING_MODE;
}
UniquePtr<uint8_t[]> decrypted_data(new (std::nothrow) uint8_t[key_len]);
if (!decrypted_data.get())
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
int bytes_decrypted = RSA_public_decrypt(signature.available_read(), signature.peek_read(),
decrypted_data.get(), rsa.get(), openssl_padding);
if (bytes_decrypted < 0)
return KM_ERROR_VERIFICATION_FAILED;
const uint8_t* compare_pos = decrypted_data.get();
size_t bytes_to_compare = bytes_decrypted;
uint8_t zero_check_result = 0;
if (padding_ == KM_PAD_NONE && data_.available_read() < bytes_to_compare) {
// If the data is short, for "unpadded" signing we zero-pad to the left. So during
// verification we should have zeros on the left of the decrypted data. Do a constant-time
// check.
const uint8_t* zero_end = compare_pos + bytes_to_compare - data_.available_read();
while (compare_pos < zero_end)
zero_check_result |= *compare_pos++;
bytes_to_compare = data_.available_read();
}
if (memcmp_s(compare_pos, data_.peek_read(), bytes_to_compare) != 0 || zero_check_result != 0)
return KM_ERROR_VERIFICATION_FAILED;
return KM_ERROR_OK;
}
keymaster_error_t RsaVerifyOperation::VerifyDigested(const Buffer& signature) {
if (!EVP_DigestVerifyFinal(&digest_ctx_, signature.peek_read(), signature.available_read()))
return KM_ERROR_VERIFICATION_FAILED;
return KM_ERROR_OK;
}
keymaster_error_t RsaCryptOperation::SetOaepDigestIfRequired(EVP_PKEY_CTX* pkey_ctx) {
if (padding() != KM_PAD_RSA_OAEP)
return KM_ERROR_OK;
assert(digest_algorithm_ != nullptr);
if (!EVP_PKEY_CTX_set_rsa_oaep_md(pkey_ctx, digest_algorithm_))
return TranslateLastOpenSslError();
// MGF1 MD is always SHA1.
if (!EVP_PKEY_CTX_set_rsa_mgf1_md(pkey_ctx, EVP_sha1()))
return TranslateLastOpenSslError();
return KM_ERROR_OK;
}
int RsaCryptOperation::GetOpensslPadding(keymaster_error_t* error) {
*error = KM_ERROR_OK;
switch (padding_) {
case KM_PAD_NONE:
return RSA_NO_PADDING;
case KM_PAD_RSA_PKCS1_1_5_ENCRYPT:
return RSA_PKCS1_PADDING;
case KM_PAD_RSA_OAEP:
return RSA_PKCS1_OAEP_PADDING;
default:
return -1;
}
}
struct EVP_PKEY_CTX_Delete {
void operator()(EVP_PKEY_CTX* p) { EVP_PKEY_CTX_free(p); }
};
keymaster_error_t RsaEncryptOperation::Finish(const AuthorizationSet& /* additional_params */,
const Buffer& /* signature */,
AuthorizationSet* /* output_params */,
Buffer* output) {
assert(output);
UniquePtr<EVP_PKEY_CTX, EVP_PKEY_CTX_Delete> ctx(
EVP_PKEY_CTX_new(rsa_key_, nullptr /* engine */));
if (!ctx.get())
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (EVP_PKEY_encrypt_init(ctx.get()) <= 0)
return TranslateLastOpenSslError();
keymaster_error_t error = SetRsaPaddingInEvpContext(ctx.get());
if (error != KM_ERROR_OK)
return error;
error = SetOaepDigestIfRequired(ctx.get());
if (error != KM_ERROR_OK)
return error;
size_t outlen;
if (EVP_PKEY_encrypt(ctx.get(), nullptr /* out */, &outlen, data_.peek_read(),
data_.available_read()) <= 0)
return TranslateLastOpenSslError();
if (!output->Reinitialize(outlen))
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
const uint8_t* to_encrypt = data_.peek_read();
size_t to_encrypt_len = data_.available_read();
UniquePtr<uint8_t[]> zero_padded;
if (padding_ == KM_PAD_NONE && to_encrypt_len < outlen) {
keymaster_error_t error = zero_pad_left(&zero_padded, outlen, data_);
if (error != KM_ERROR_OK)
return error;
to_encrypt = zero_padded.get();
to_encrypt_len = outlen;
}
if (EVP_PKEY_encrypt(ctx.get(), output->peek_write(), &outlen, to_encrypt, to_encrypt_len) <= 0)
return TranslateLastOpenSslError();
if (!output->advance_write(outlen))
return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
keymaster_error_t RsaDecryptOperation::Finish(const AuthorizationSet& /* additional_params */,
const Buffer& /* signature */,
AuthorizationSet* /* output_params */,
Buffer* output) {
assert(output);
UniquePtr<EVP_PKEY_CTX, EVP_PKEY_CTX_Delete> ctx(
EVP_PKEY_CTX_new(rsa_key_, nullptr /* engine */));
if (!ctx.get())
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (EVP_PKEY_decrypt_init(ctx.get()) <= 0)
return TranslateLastOpenSslError();
keymaster_error_t error = SetRsaPaddingInEvpContext(ctx.get());
if (error != KM_ERROR_OK)
return error;
error = SetOaepDigestIfRequired(ctx.get());
if (error != KM_ERROR_OK)
return error;
size_t outlen;
if (EVP_PKEY_decrypt(ctx.get(), nullptr /* out */, &outlen, data_.peek_read(),
data_.available_read()) <= 0)
return TranslateLastOpenSslError();
if (!output->Reinitialize(outlen))
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
const uint8_t* to_decrypt = data_.peek_read();
size_t to_decrypt_len = data_.available_read();
UniquePtr<uint8_t[]> zero_padded;
if (padding_ == KM_PAD_NONE && to_decrypt_len < outlen) {
keymaster_error_t error = zero_pad_left(&zero_padded, outlen, data_);
if (error != KM_ERROR_OK)
return error;
to_decrypt = zero_padded.get();
to_decrypt_len = outlen;
}
if (EVP_PKEY_decrypt(ctx.get(), output->peek_write(), &outlen, to_decrypt, to_decrypt_len) <= 0)
return TranslateLastOpenSslError();
if (!output->advance_write(outlen))
return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
} // namespace keymaster