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qpdf/libqpdf/QPDFCrypto_gnutls.cc
Jay Berkenbilt 88bedb41fe Implement gnutls crypto provider (fixes #218)
Thanks to Zdenek Dohnal <zdohnal@redhat.com> for contributing the code
used for the gnutls crypto provider.
2019-11-09 09:53:38 -05:00

278 lines
6.2 KiB
C++

#include <qpdf/QPDFCrypto_gnutls.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/QUtil.hh>
#include <cstring>
QPDFCrypto_gnutls::QPDFCrypto_gnutls() :
hash_ctx(nullptr),
cipher_ctx(nullptr),
sha2_bits(0),
encrypt(false),
cbc_mode(false),
aes_key_data(nullptr),
aes_key_len(0)
{
memset(digest, 0, sizeof(digest));
}
QPDFCrypto_gnutls::~QPDFCrypto_gnutls()
{
if (this->hash_ctx)
{
gnutls_hash_deinit(this->hash_ctx, digest);
}
if (cipher_ctx)
{
gnutls_cipher_deinit(this->cipher_ctx);
}
this->aes_key_data = nullptr;
this->aes_key_len = 0;
}
void
QPDFCrypto_gnutls::MD5_init()
{
MD5_finalize();
int code = gnutls_hash_init(&this->hash_ctx, GNUTLS_DIG_MD5);
if (code < 0)
{
this->hash_ctx = nullptr;
throw std::runtime_error(
std::string("gnutls: MD5 error: ") +
std::string(gnutls_strerror(code)));
}
}
void
QPDFCrypto_gnutls::MD5_update(unsigned char const* data, size_t len)
{
gnutls_hash(this->hash_ctx, data, len);
}
void
QPDFCrypto_gnutls::MD5_finalize()
{
if (this->hash_ctx)
{
gnutls_hash_deinit(this->hash_ctx, this->digest);
this->hash_ctx = nullptr;
}
}
void
QPDFCrypto_gnutls::MD5_digest(MD5_Digest d)
{
memcpy(d, this->digest, sizeof(MD5_Digest));
}
void
QPDFCrypto_gnutls::RC4_init(unsigned char const* key_data, int key_len)
{
RC4_finalize();
if (key_len == -1)
{
key_len = QIntC::to_int(
strlen(reinterpret_cast<char const*>(key_data)));
}
gnutls_datum_t key;
key.data = const_cast<unsigned char*>(key_data);
key.size = QIntC::to_uint(key_len);
int code = gnutls_cipher_init(
&this->cipher_ctx, GNUTLS_CIPHER_ARCFOUR_128, &key, nullptr);
if (code < 0)
{
this->cipher_ctx = nullptr;
throw std::runtime_error(
std::string("gnutls: RC4 error: ") +
std::string(gnutls_strerror(code)));
}
}
void
QPDFCrypto_gnutls::RC4_process(unsigned char* in_data, size_t len,
unsigned char* out_data)
{
if (nullptr == out_data)
{
out_data = in_data;
}
gnutls_cipher_encrypt2(this->cipher_ctx, in_data, len, out_data, len);
}
void
QPDFCrypto_gnutls::RC4_finalize()
{
if (this->cipher_ctx)
{
gnutls_cipher_deinit(this->cipher_ctx);
this->cipher_ctx = nullptr;
}
}
void
QPDFCrypto_gnutls::SHA2_init(int bits)
{
SHA2_finalize();
gnutls_digest_algorithm_t alg = GNUTLS_DIG_UNKNOWN;
switch (bits)
{
case 256:
alg = GNUTLS_DIG_SHA256;
break;
case 384:
alg = GNUTLS_DIG_SHA384;
break;
case 512:
alg = GNUTLS_DIG_SHA512;
break;
default:
badBits();
break;
}
this->sha2_bits = bits;
int code = gnutls_hash_init(&this->hash_ctx, alg);
if (code < 0)
{
this->hash_ctx = nullptr;
throw std::runtime_error(
std::string("gnutls: SHA") + QUtil::int_to_string(bits) +
" error: " + std::string(gnutls_strerror(code)));
}
}
void
QPDFCrypto_gnutls::SHA2_update(unsigned char const* data, size_t len)
{
gnutls_hash(this->hash_ctx, data, len);
}
void
QPDFCrypto_gnutls::SHA2_finalize()
{
if (this->hash_ctx)
{
gnutls_hash_deinit(this->hash_ctx, this->digest);
this->hash_ctx = nullptr;
}
}
std::string
QPDFCrypto_gnutls::SHA2_digest()
{
std::string result;
switch (this->sha2_bits)
{
case 256:
result = std::string(reinterpret_cast<char*>(this->digest), 32);
break;
case 384:
result = std::string(reinterpret_cast<char*>(this->digest), 48);
break;
case 512:
result = std::string(reinterpret_cast<char*>(this->digest), 64);
break;
default:
badBits();
break;
}
return result;
}
void
QPDFCrypto_gnutls::rijndael_init(
bool encrypt, unsigned char const* key_data, size_t key_len,
bool cbc_mode, unsigned char* cbc_block)
{
rijndael_finalize();
this->encrypt = encrypt;
this->cbc_mode = cbc_mode;
if (! cbc_mode)
{
// Save the key so we can re-initialize.
this->aes_key_data = key_data;
this->aes_key_len = key_len;
}
gnutls_cipher_algorithm_t alg = GNUTLS_CIPHER_UNKNOWN;
gnutls_datum_t cipher_key;
gnutls_datum_t iv;
cipher_key.data = const_cast<unsigned char*>(key_data);
switch(key_len)
{
case 16:
alg = GNUTLS_CIPHER_AES_128_CBC;
break;
case 32:
alg = GNUTLS_CIPHER_AES_256_CBC;
break;
case 24:
alg = GNUTLS_CIPHER_AES_192_CBC;
break;
default:
alg = GNUTLS_CIPHER_AES_128_CBC;
break;
}
cipher_key.size = QIntC::to_uint(gnutls_cipher_get_key_size(alg));
iv.data = cbc_block;
iv.size = rijndael_buf_size;
int code = gnutls_cipher_init(&this->cipher_ctx, alg, &cipher_key, &iv);
if (code < 0)
{
this->cipher_ctx = nullptr;
throw std::runtime_error(
std::string("gnutls: AES error: ") +
std::string(gnutls_strerror(code)));
}
}
void
QPDFCrypto_gnutls::rijndael_process(unsigned char* in_data,
unsigned char* out_data)
{
if (this->encrypt)
{
gnutls_cipher_encrypt2(this->cipher_ctx,
in_data, rijndael_buf_size,
out_data, rijndael_buf_size);
}
else
{
gnutls_cipher_decrypt2(this->cipher_ctx,
in_data, rijndael_buf_size,
out_data, rijndael_buf_size);
}
// Gnutls doesn't support AES in ECB (non-CBC) mode, but the
// result is the same as if you just reset the cbc block to all
// zeroes each time. We jump through a few hoops here to make this
// work.
if (! this->cbc_mode)
{
static unsigned char zeroes[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
rijndael_init(this->encrypt, this->aes_key_data, this->aes_key_len,
false, zeroes);
}
}
void
QPDFCrypto_gnutls::rijndael_finalize()
{
if (this->cipher_ctx)
{
gnutls_cipher_deinit(this->cipher_ctx);
this->cipher_ctx = nullptr;
}
}
void
QPDFCrypto_gnutls::badBits()
{
throw std::logic_error("SHA2 (gnutls) has bits != 256, 384, or 512");
}