I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#include <zlib.h> // for crc32
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include "Base.h"
#include "Crypto.h"
#include "Log.h"
#include "Timestamp.h"
#include "I2PEndian.h"
#include "Ed25519.h"
#include "Blinding.h"
namespace i2p
{
namespace data
{
BlindedPublicKey::BlindedPublicKey (std::shared_ptr<const IdentityEx> identity, SigningKeyType blindedKeyType):
m_BlindedSigType (blindedKeyType)
{
if (!identity) return;
auto len = identity->GetSigningPublicKeyLen ();
m_PublicKey.resize (len);
memcpy (m_PublicKey.data (), identity->GetSigningPublicKeyBuffer (), len);
m_SigType = identity->GetSigningKeyType ();
}
BlindedPublicKey::BlindedPublicKey (const std::string& b33)
{
uint8_t addr[40]; // TODO: define length from b33
size_t l = i2p::data::Base32ToByteStream (b33.c_str (), b33.length (), addr, 40);
uint32_t checksum = crc32 (0, addr + 3, l - 3);
// checksum is Little Endian
addr[0] ^= checksum; addr[1] ^= (checksum >> 8); addr[2] ^= (checksum >> 16);
uint8_t flag = addr[0];
size_t offset = 1;
if (flag & 0x01) // two bytes signatures
{
m_SigType = bufbe16toh (addr + offset); offset += 2;
m_BlindedSigType = bufbe16toh (addr + offset); offset += 2;
}
else // one byte sig
{
m_SigType = addr[offset]; offset++;
m_BlindedSigType = addr[offset]; offset++;
}
std::unique_ptr<i2p::crypto::Verifier> blindedVerifier (i2p::data::IdentityEx::CreateVerifier (m_SigType));
if (blindedVerifier)
{
auto len = blindedVerifier->GetPublicKeyLen ();
if (offset + len <= l)
{
m_PublicKey.resize (len);
memcpy (m_PublicKey.data (), addr + offset, len);
}
else
LogPrint (eLogError, "Blinding: public key in b33 address is too short for signature type ", (int)m_SigType);
}
else
LogPrint (eLogError, "Blinding: unknown signature type ", (int)m_SigType, " in b33");
}
std::string BlindedPublicKey::ToB33 () const
{
if (m_PublicKey.size () > 32) return ""; // assume 25519
uint8_t addr[35]; char str[60]; // TODO: define actual length
addr[0] = 0; // flags
addr[1] = m_SigType; // sig type
addr[2] = m_BlindedSigType; // blinded sig type
memcpy (addr + 3, m_PublicKey.data (), m_PublicKey.size ());
uint32_t checksum = crc32 (0, addr + 3, m_PublicKey.size ());
// checksum is Little Endian
addr[0] ^= checksum; addr[1] ^= (checksum >> 8); addr[2] ^= (checksum >> 16);
auto l = ByteStreamToBase32 (addr, m_PublicKey.size () + 3, str, 60);
return std::string (str, str + l);
}
void BlindedPublicKey::GetCredential (uint8_t * credential) const
{
// A = destination's signing public key
// stA = signature type of A, 2 bytes big endian
uint16_t stA = htobe16 (GetSigType ());
// stA1 = signature type of blinded A, 2 bytes big endian
uint16_t stA1 = htobe16 (GetBlindedSigType ());
// credential = H("credential", A || stA || stA1)
H ("credential", { {GetPublicKey (), GetPublicKeyLen ()}, {(const uint8_t *)&stA, 2}, {(const uint8_t *)&stA1, 2} }, credential);
}
void BlindedPublicKey::GetSubcredential (const uint8_t * blinded, size_t len, uint8_t * subcredential) const
{
uint8_t credential[32];
GetCredential (credential);
// subcredential = H("subcredential", credential || blindedPublicKey)
H ("subcredential", { {credential, 32}, {blinded, len} }, subcredential);
}
void BlindedPublicKey::GenerateAlpha (const char * date, uint8_t * seed) const
{
uint16_t stA = htobe16 (GetSigType ()), stA1 = htobe16 (GetBlindedSigType ());
uint8_t salt[32];
//seed = HKDF(H("I2PGenerateAlpha", keydata), datestring || secret, "i2pblinding1", 64)
H ("I2PGenerateAlpha", { {GetPublicKey (), GetPublicKeyLen ()}, {(const uint8_t *)&stA, 2}, {(const uint8_t *)&stA1, 2} }, salt);
i2p::crypto::HKDF (salt, (const uint8_t *)date, 8, "i2pblinding1", seed);
}
void BlindedPublicKey::GetBlindedKey (const char * date, uint8_t * blindedKey) const
{
uint8_t seed[64];
GenerateAlpha (date, seed);
i2p::crypto::GetEd25519 ()->BlindPublicKey (GetPublicKey (), seed, blindedKey);
}
void BlindedPublicKey::BlindPrivateKey (const uint8_t * priv, const char * date, uint8_t * blindedPriv, uint8_t * blindedPub) const
{
uint8_t seed[64];
GenerateAlpha (date, seed);
i2p::crypto::GetEd25519 ()->BlindPrivateKey (priv, seed, blindedPriv, blindedPub);
}
void BlindedPublicKey::H (const std::string& p, const std::vector<std::pair<const uint8_t *, size_t> >& bufs, uint8_t * hash) const
{
SHA256_CTX ctx;
SHA256_Init (&ctx);
SHA256_Update (&ctx, p.c_str (), p.length ());
for (const auto& it: bufs)
SHA256_Update (&ctx, it.first, it.second);
SHA256_Final (hash, &ctx);
}
i2p::data::IdentHash BlindedPublicKey::GetStoreHash (const char * date) const
{
i2p::data::IdentHash hash;
if (m_BlindedSigType == i2p::data::SIGNING_KEY_TYPE_REDDSA_SHA512_ED25519 ||
m_BlindedSigType == SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519)
{
uint8_t blinded[32];
if (date)
GetBlindedKey (date, blinded);
else
{
char currentDate[9];
i2p::util::GetCurrentDate (currentDate);
GetBlindedKey (currentDate, blinded);
}
auto stA1 = htobe16 (m_BlindedSigType);
SHA256_CTX ctx;
SHA256_Init (&ctx);
SHA256_Update (&ctx, (const uint8_t *)&stA1, 2);
SHA256_Update (&ctx, blinded, 32);
SHA256_Final ((uint8_t *)hash, &ctx);
}
else
LogPrint (eLogError, "Blinding: blinded key type ", (int)m_BlindedSigType, " is not supported");
return hash;
}
}
}