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// RsaPrivateKey.cpp
#include "Globals.h"
#include "RsaPrivateKey.h"
#include "mbedtls/pk.h"
cRsaPrivateKey::cRsaPrivateKey(void)
{
mbedtls_rsa_init(&m_Rsa);
m_CtrDrbg.Initialize("RSA", 3);
}
cRsaPrivateKey::cRsaPrivateKey(const cRsaPrivateKey & a_Other)
{
mbedtls_rsa_init(&m_Rsa);
mbedtls_rsa_copy(&m_Rsa, &a_Other.m_Rsa);
m_CtrDrbg.Initialize("RSA", 3);
}
cRsaPrivateKey::~cRsaPrivateKey()
{
mbedtls_rsa_free(&m_Rsa);
}
bool cRsaPrivateKey::Generate(unsigned a_KeySizeBits)
{
int res = mbedtls_rsa_gen_key(&m_Rsa, mbedtls_ctr_drbg_random, m_CtrDrbg.GetInternal(), a_KeySizeBits, 65537);
if (res != 0)
{
LOG("RSA key generation failed: -0x%x", -res);
return false;
}
return true;
}
ContiguousByteBuffer cRsaPrivateKey::GetPubKeyDER(void)
{
class cPubKey
{
public:
cPubKey(mbedtls_rsa_context * a_Rsa) :
m_IsValid(false)
{
mbedtls_pk_init(&m_Key);
if (mbedtls_pk_setup(&m_Key, mbedtls_pk_info_from_type(MBEDTLS_PK_RSA)) != 0)
{
ASSERT(!"Cannot init PrivKey context");
return;
}
if (mbedtls_rsa_copy(mbedtls_pk_rsa(m_Key), a_Rsa) != 0)
{
ASSERT(!"Cannot copy PrivKey to PK context");
return;
}
m_IsValid = true;
}
~cPubKey()
{
if (m_IsValid)
{
mbedtls_pk_free(&m_Key);
}
}
operator mbedtls_pk_context *(void) { return &m_Key; }
protected:
bool m_IsValid;
mbedtls_pk_context m_Key;
} PkCtx(&m_Rsa);
unsigned char buf[3000];
int res = mbedtls_pk_write_pubkey_der(PkCtx, buf, sizeof(buf));
if (res < 0)
{
return {};
}
return {reinterpret_cast<const std::byte *>(buf + sizeof(buf) - res), static_cast<size_t>(res)};
}
int cRsaPrivateKey::Decrypt(
const ContiguousByteBufferView a_EncryptedData,
Byte * a_DecryptedData,
size_t a_DecryptedMaxLength
)
{
const auto KeyLength = mbedtls_rsa_get_len(&m_Rsa);
if (a_EncryptedData.size() < KeyLength)
{
LOGD(
"%s: Invalid a_EncryptedLength: got %zu, exp at least %zu",
__FUNCTION__,
a_EncryptedData.size(),
KeyLength
);
ASSERT(!"Invalid a_DecryptedMaxLength!");
return -1;
}
if (a_DecryptedMaxLength < KeyLength)
{
LOGD(
"%s: Invalid a_DecryptedMaxLength: got %zu, exp at least %zu",
__FUNCTION__,
a_DecryptedMaxLength,
KeyLength
);
ASSERT(!"Invalid a_DecryptedMaxLength!");
return -1;
}
size_t DecryptedLength;
int res = mbedtls_rsa_pkcs1_decrypt(
&m_Rsa,
mbedtls_ctr_drbg_random,
m_CtrDrbg.GetInternal(),
&DecryptedLength,
reinterpret_cast<const unsigned char *>(a_EncryptedData.data()),
a_DecryptedData,
a_DecryptedMaxLength
);
if (res != 0)
{
return -1;
}
return static_cast<int>(DecryptedLength);
}
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