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/* Adapted from OpenSSL's rsa_pss.c from OpenSSL 3.0.1 */
/*
* Copyright 2005-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "jni.h"
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>
#include <array>
static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
static char opensslerr[1024];
extern "C" jbyteArray Java_de_blinkt_openvpn_core_NativeUtils_rsapss(JNIEnv *env,
jclass,
jint hashtype,
jint MSBits,
jint rsa_size,
jbyteArray from) {
/*
unsigned char *EM,
const unsigned char *mHash,
const EVP_MD *Hash, const EVP_MD *mgf1Hash,
int sLen)
*/
jbyte *data = env->GetByteArrayElements(from, NULL);
int datalen = env->GetArrayLength(from);
const auto *mHash = reinterpret_cast<const unsigned char *>(data);
const EVP_MD *Hash;
if (hashtype == 0) {
Hash = EVP_md5();
} else if (hashtype == 1) {
Hash = EVP_sha1();
} else if (hashtype == 2) {
Hash = EVP_sha224();
} else if (hashtype == 3) {
Hash = EVP_sha256();
} else if (hashtype == 4) {
Hash = EVP_sha384();
} else if (hashtype == 5) {
Hash = EVP_sha512();
}
const EVP_MD *mgf1Hash = Hash;
int ret = 0;
int maskedDBLen, emLen;
unsigned char *H, *salt = nullptr, *p;
EVP_MD_CTX *ctx = nullptr;
int hLen = EVP_MD_get_size(Hash);
int sLen = hLen; /* RSA_PSS_SALTLEN_DIGEST */
std::array<unsigned char, 2048> buf{};
unsigned char *EM = buf.data();
if (hLen < 0)
goto err;
emLen = rsa_size;
if (MSBits == 0) {
*EM++ = 0;
emLen--;
}
if (emLen < hLen + 2) {
goto err;
}
if (sLen == RSA_PSS_SALTLEN_MAX) {
sLen = emLen - hLen - 2;
} else if (sLen > emLen - hLen - 2) {
goto err;
}
if (sLen > 0) {
salt = (unsigned char *) OPENSSL_malloc(sLen);
if (salt == nullptr) {
goto err;
}
if (RAND_bytes_ex(nullptr, salt, sLen, 0) <= 0)
goto err;
}
maskedDBLen = emLen - hLen - 1;
H = EM + maskedDBLen;
ctx = EVP_MD_CTX_new();
if (ctx == nullptr)
goto err;
if (!EVP_DigestInit_ex(ctx, Hash, nullptr)
|| !EVP_DigestUpdate(ctx, zeroes, sizeof(zeroes))
|| !EVP_DigestUpdate(ctx, mHash, hLen))
goto err;
if (sLen && !EVP_DigestUpdate(ctx, salt, sLen))
goto err;
if (!EVP_DigestFinal_ex(ctx, H, nullptr))
goto err;
/* Generate dbMask in place then perform XOR on it */
if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash))
goto err;
p = EM;
/*
* Initial PS XORs with all zeroes which is a NOP so just update pointer.
* Note from a test above this value is guaranteed to be non-negative.
*/
p += emLen - sLen - hLen - 2;
*p++ ^= 0x1;
if (sLen > 0) {
for (int i = 0; i < sLen; i++)
*p++ ^= salt[i];
}
if (MSBits)
EM[0] &= 0xFF >> (8 - MSBits);
/* H is already in place so just set final 0xbc */
EM[emLen - 1] = 0xbc;
ret = 1;
err:
EVP_MD_CTX_free(ctx);
OPENSSL_clear_free(salt, (size_t) sLen); /* salt != NULL implies sLen > 0 */
jbyteArray jb;
jb = env->NewByteArray(emLen);
env->SetByteArrayRegion(jb, 0, emLen, (jbyte *) EM);
return jb;
}
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