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H and HKDF for encrypted LeaseSet2

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orignal 2019-02-27 15:52:47 -05:00
parent 2f0115c300
commit af65af5be9
2 changed files with 66 additions and 9 deletions
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66
libi2pd/LeaseSet.cpp
View file

@ -1,4 +1,6 @@
#include <string.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include "I2PEndian.h"
#include "Crypto.h"
#include "Log.h"
@ -251,15 +253,21 @@ namespace data
}
LeaseSet2::LeaseSet2 (uint8_t storeType, const uint8_t * buf, size_t len, bool storeLeases):
LeaseSet (storeLeases), m_StoreType (storeType), m_PublishedTimestamp (0)
LeaseSet (storeLeases), m_StoreType (storeType)
{
SetBuffer (buf, len);
if (storeType == NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
ReadFromBufferEncrypted (buf, len);
ReadFromBufferEncrypted (buf, len, nullptr);
else
ReadFromBuffer (buf, len);
}
LeaseSet2::LeaseSet2 (const uint8_t * buf, size_t len, std::shared_ptr<const IdentityEx> identity):
LeaseSet (true), m_StoreType (NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
{
ReadFromBufferEncrypted (buf, len, identity);
}
void LeaseSet2::Update (const uint8_t * buf, size_t len, bool verifySignature)
{
SetBuffer (buf, len);
@ -414,7 +422,7 @@ namespace data
return offset;
}
void LeaseSet2::ReadFromBufferEncrypted (const uint8_t * buf, size_t len)
void LeaseSet2::ReadFromBufferEncrypted (const uint8_t * buf, size_t len, std::shared_ptr<const IdentityEx> identity)
{
size_t offset = 0;
// blinded key
@ -424,10 +432,12 @@ namespace data
if (!blindedVerifier) return;
auto blindedKeyLen = blindedVerifier->GetPublicKeyLen ();
if (offset + blindedKeyLen >= len) return;
blindedVerifier->SetPublicKey (buf + offset); offset += blindedKeyLen;
const uint8_t * blindedPublicKey = buf + offset;
blindedVerifier->SetPublicKey (blindedPublicKey); offset += blindedKeyLen;
// expiration
if (offset + 8 >= len) return;
m_PublishedTimestamp = bufbe32toh (buf + offset); offset += 4; // published timestamp (seconds)
const uint8_t * publishedTimestamp = buf + offset;
m_PublishedTimestamp = bufbe32toh (publishedTimestamp); offset += 4; // published timestamp (seconds)
uint16_t expires = bufbe16toh (buf + offset); offset += 2; // expires (seconds)
SetExpirationTime ((m_PublishedTimestamp + expires)*1000LL); // in milliseconds
uint16_t flags = bufbe16toh (buf + offset); offset += 2; // flags
@ -443,11 +453,53 @@ namespace data
}
// outer ciphertext
if (offset + 2 > len) return;
uint16_t lenOuterCiphertext = bufbe16toh (buf + offset); offset += 2 + lenOuterCiphertext;
uint16_t lenOuterCiphertext = bufbe16toh (buf + offset); offset += 2;
const uint8_t * outerCiphertext = buf + offset;
offset += lenOuterCiphertext;
// verify signature
bool verified = m_TransientVerifier ? VerifySignature (m_TransientVerifier, buf, len, offset) :
VerifySignature (blindedVerifier, buf, len, offset);
SetIsValid (verified);
SetIsValid (verified);
// handle ciphertext
if (verified && identity && lenOuterCiphertext >= 32)
{
size_t l = identity->GetFullLen();
std::vector<uint8_t> destination (l);
l = identity->ToBuffer (destination.data(), l);
uint8_t credential[32], subcredential[36];
// credential = H("credential", Destination)
H ("credential", { {destination.data(), l} }, credential);
// subcredential = H("subcredential", credential || blindedPublicKey)
H ("subcredential", { {credential, 32}, {blindedPublicKey, blindedKeyLen} }, subcredential);
// outerInput = subcredential || publishedTimestamp
memcpy (subcredential + 32, publishedTimestamp, 4);
// outerSalt = outerCiphertext[32:end]
// keys = HKDF(outerSalt, outerInput, "ELS2_L1K", 44)
uint8_t outerKey[44];
HKDF (outerCiphertext + lenOuterCiphertext - 32, {subcredential, 36}, "ELS2_L1K", outerKey, 44);
// decrypt using chacha20
}
}
void LeaseSet2::H (const std::string& p, const std::vector<std::pair<const uint8_t *, size_t> >& bufs, uint8_t * hash)
{
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);
}
void LeaseSet2::HKDF (const uint8_t * salt, const std::pair<const uint8_t *, size_t>& ikm, const char * info, uint8_t * out, size_t outLen)
{
uint8_t prk[32], t[41]; unsigned int len;
HMAC(EVP_sha256(), salt, 32, ikm.first, ikm.second, prk, &len);
memcpy (t, info, 8); t[8] = 0x01;
HMAC(EVP_sha256(), prk, 32, t, 9, out, &len);
memcpy (t, out, 32); memcpy (t + 32, info, 8); t[40] = 0x02;
HMAC(EVP_sha256(), prk, 32, t, 41, t, &len);
memcpy (out + 32, t, outLen % 32); // outLen doesn't exceed 64
}
void LeaseSet2::Encrypt (const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx) const

9
libi2pd/LeaseSet.h
View file

@ -133,6 +133,7 @@ namespace data
public:
LeaseSet2 (uint8_t storeType, const uint8_t * buf, size_t len, bool storeLeases = true);
LeaseSet2 (const uint8_t * buf, size_t len, std::shared_ptr<const IdentityEx> identity); // store type 5, called from local netdb only
uint8_t GetStoreType () const { return m_StoreType; };
uint32_t GetPublishedTimestamp () const { return m_PublishedTimestamp; };
std::shared_ptr<const i2p::crypto::Verifier> GetTransientVerifier () const { return m_TransientVerifier; };
@ -144,7 +145,7 @@ namespace data
private:
void ReadFromBuffer (const uint8_t * buf, size_t len, bool readIdentity = true, bool verifySignature = true);
void ReadFromBufferEncrypted (const uint8_t * buf, size_t len);
void ReadFromBufferEncrypted (const uint8_t * buf, size_t len, std::shared_ptr<const IdentityEx> identity);
size_t ReadStandardLS2TypeSpecificPart (const uint8_t * buf, size_t len);
size_t ReadMetaLS2TypeSpecificPart (const uint8_t * buf, size_t len);
@ -153,10 +154,14 @@ namespace data
uint64_t ExtractTimestamp (const uint8_t * buf, size_t len) const;
// for encrypted LS
void H (const std::string& p, const std::vector<std::pair<const uint8_t *, size_t> >& bufs, uint8_t * hash);
void HKDF (const uint8_t * salt, const std::pair<const uint8_t *, size_t>& ikm, const char * info, uint8_t * out, size_t outLen); // salt - 32, info - 8
private:
uint8_t m_StoreType;
uint32_t m_PublishedTimestamp;
uint32_t m_PublishedTimestamp = 0;
std::shared_ptr<i2p::crypto::Verifier> m_TransientVerifier;
std::shared_ptr<i2p::crypto::CryptoKeyEncryptor> m_Encryptor; // for standardLS2
};