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/* Copyright 2015 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <common/publickey.h>
#include <string.h>
#include <string>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/rand.h>
#include <common/gnubby.h>
extern bool FLAGS_verbose;
#define VERBOSE(...) do{if(FLAGS_verbose){fprintf(stderr, __VA_ARGS__);fflush(stderr);}}while(0)
#define WARN(...) do{fprintf(stderr, __VA_ARGS__);}while(0)
#define FATAL(...) do{fprintf(stderr, __VA_ARGS__);abort();}while(0)
PublicKey::PublicKey(const std::string& filename) : key_(NULL), publicOnly_(true) {
EVP_PKEY* pkey = NULL;
BIO* bio = BIO_new(BIO_s_file());
OpenSSL_add_all_ciphers(); // needed to decrypt PEM.
if (BIO_read_filename(bio, filename.c_str()) == 1) {
pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
if (pkey) {
publicOnly_ = false;
} else {
// Try read as public key.
(void)BIO_reset(bio);
pkey = PEM_read_bio_PUBKEY(bio, NULL, NULL, NULL);
if (pkey) {
VERBOSE("read public key only, assuming gnubby for signing..\n");
}
}
}
if (!pkey) {
WARN("loadKey: failed to load RSA key from '%s'\n", filename.c_str());
}
BIO_free_all(bio);
key_ = pkey;
}
PublicKey::~PublicKey() {
if (key_) {
EVP_PKEY_free(key_);
key_ = NULL;
}
}
bool PublicKey::ok() {
return key_ != NULL;
}
size_t PublicKey::nwords() {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
size_t result = (BN_num_bytes(rsa->n) + 3) / 4;
RSA_free(rsa);
return result;
}
uint32_t PublicKey::public_exponent() {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
uint32_t result = BN_get_word(rsa->e);
RSA_free(rsa);
return result;
}
uint32_t PublicKey::n0inv() {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
BN_CTX* ctx = BN_CTX_new();
BIGNUM* r = BN_new();
BIGNUM* rem = BN_new();
BIGNUM* n0inv = BN_new();
BN_set_bit(r, 32); // 2**32
BN_div(NULL, rem, rsa->n, r, ctx); // low 32 bit
BN_mod_inverse(n0inv, rem, r, ctx);
uint32_t result = 0 - BN_get_word(n0inv);
BN_free(n0inv);
BN_free(rem);
BN_free(r);
BN_CTX_free(ctx);
RSA_free(rsa);
return result;
}
void PublicKey::print(const char* tag, size_t nwords, BIGNUM* n) {
BN_CTX* ctx = BN_CTX_new();
BIGNUM* N = BN_new();
BIGNUM* r = BN_new();
BIGNUM* d = BN_new();
BIGNUM* rem = BN_new();
BN_set_bit(r, 32); // 2^32
BN_copy(N, n);
printf("const uint32_t %s[%lu + 1] = {", tag, nwords);
printf("0x%08x, ", n0inv());
for (size_t i = 0; i < nwords; ++i) {
if (i) printf(", ");
BN_div(N, rem, N, r, ctx);
printf("0x%08lx", BN_get_word(rem));
}
printf("};\n");
BN_free(rem);
BN_free(d);
BN_free(r);
BN_free(N);
BN_CTX_free(ctx);
}
void PublicKey::print(const char* tag, size_t nwords,
uint8_t* data, size_t len) {
BIGNUM* n = BN_bin2bn(data, len, NULL);
print(tag, nwords, n);
BN_free(n);
}
void PublicKey::print(const char* tag) {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
print(tag, rwords(), rsa->n);
RSA_free(rsa);
}
/*static*/
void PublicKey::toArray(uint32_t* dst, size_t nwords, BIGNUM* n) {
BN_CTX* ctx = BN_CTX_new();
BIGNUM* N = BN_new();
BIGNUM* r = BN_new();
BIGNUM* d = BN_new();
BIGNUM* rem = BN_new();
BN_set_bit(r, 32); // 2^32
BN_copy(N, n);
for (size_t i = 0; i < nwords; ++i) {
BN_div(N, rem, N, r, ctx);
*dst++ = BN_get_word(rem);
}
BN_free(rem);
BN_free(d);
BN_free(r);
BN_free(N);
BN_CTX_free(ctx);
}
void PublicKey::modToArray(uint32_t* dst, size_t nwords) {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
toArray(dst, nwords, rsa->n);
RSA_free(rsa);
}
int PublicKey::encrypt(uint8_t* msg, int msglen, uint8_t* out) {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
int result =
RSA_public_encrypt(msglen, msg, out, rsa, RSA_PKCS1_OAEP_PADDING);
RSA_free(rsa);
return result;
}
int PublicKey::decrypt(uint8_t* msg, int msglen, uint8_t* out) {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
int result =
RSA_private_decrypt(msglen, msg, out, rsa, RSA_PKCS1_OAEP_PADDING);
RSA_free(rsa);
return result;
}
int PublicKey::raw(uint8_t* in, int inlen, BIGNUM** out) {
RSA* rsa = EVP_PKEY_get1_RSA(key_);
BN_CTX* ctx = BN_CTX_new();
BIGNUM* m = BN_new();
BIGNUM* r = BN_new();
BN_bin2bn(in, inlen, m);
int result = BN_mod_exp(r, m, rsa->d, rsa->n, ctx);
if (result == 1) {
*out = BN_dup(r);
}
BN_free(r);
BN_free(m);
BN_CTX_free(ctx);
RSA_free(rsa);
return result;
}
// Sign message.
// Produces signature * R mod N (Montgomery format).
// Returns 1 on success.
int PublicKey::sign(const void* msg, size_t msglen, BIGNUM** output) {
int result = 0;
EVP_MD_CTX* ctx = NULL;
BN_CTX* bnctx = NULL;
BIGNUM* tmp = NULL;
RSA* rsa = NULL;
uint8_t* sig = NULL;
unsigned int siglen = 0;
unsigned int tmplen = EVP_PKEY_size(key_);
ctx = EVP_MD_CTX_create();
if (!ctx) goto __fail;
EVP_MD_CTX_init(ctx);
EVP_DigestInit(ctx, EVP_sha256());
if (EVP_DigestUpdate(ctx, msg, msglen) != 1) goto __fail;
sig = (uint8_t*)malloc(tmplen);
if (publicOnly_) {
fprintf(stderr, "gnubby signing.."); fflush(stderr);
// TODO: 2k -> gnubby, 3k -> HSM?
Gnubby gnubby;
result = gnubby.Sign(ctx, sig, &siglen, key_);
fprintf(stderr, "gnubby.Sign: %d\n", result);
} else {
VERBOSE("ossl signing..");
result = EVP_SignFinal(ctx, sig, &siglen, key_);
VERBOSE("EVP_SignFinal: %d\n", result);
}
if (result != 1) goto __fail;
tmp = BN_bin2bn(sig, siglen, NULL);
// compute R*sig mod N
rsa = EVP_PKEY_get1_RSA(key_);
if (BN_lshift(tmp, tmp, rwords() * 32) != 1) goto __fail;
bnctx = BN_CTX_new();
if (BN_mod(tmp, tmp, rsa->n, bnctx) != 1) goto __fail;
*output = BN_dup(tmp);
__fail:
if (tmp) BN_free(tmp);
if (rsa) RSA_free(rsa);
if (sig) free(sig);
if (ctx) EVP_MD_CTX_destroy(ctx);
if (bnctx) BN_CTX_free(bnctx);
return result;
}
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