From f6639dd11b22c793082d9be53e049fdeb9039d60 Mon Sep 17 00:00:00 2001 From: Miguel Freitas Date: Fri, 9 Aug 2013 00:12:16 -0300 Subject: [PATCH] include implementation for ECIES (ECC + AES + SHA) for asymetric encryption --- src/key.cpp | 397 ++++++++++++++++++++++++++++++++++++++++++++++++ src/key.h | 29 ++++ src/twister.cpp | 27 ++++ 3 files changed, 453 insertions(+) diff --git a/src/key.cpp b/src/key.cpp index 1ab4c62e..787b62dc 100644 --- a/src/key.cpp +++ b/src/key.cpp @@ -5,9 +5,15 @@ #include #include #include +#include +#include +#include #include "key.h" +#ifdef DEBUG_ECIES +#include "util.h" +#endif // anonymous namespace with local implementation code (OpenSSL interaction) namespace { @@ -123,6 +129,14 @@ err: return ret; } +void * ecies_key_derivation(const void *input, size_t ilen, void *output, size_t *olen) { + if (*olen < SHA512_DIGEST_LENGTH) { + return NULL; + } + *olen = SHA512_DIGEST_LENGTH; + return SHA512(static_cast(input), ilen, static_cast(output)); +} + // RAII Wrapper around OpenSSL's EC_KEY class CECKey { private: @@ -254,6 +268,369 @@ public: ECDSA_SIG_free(sig); return ret; } + + /** + * @file /cryptron/ecies.c + * + * @brief ECIES encryption/decryption functions. + * + * $Author: Ladar Levison $ + * $Website: http://lavabit.com $ + * $Date: 2010/08/06 06:02:03 $ + * $Revision: a51931d0f81f6abe29ca91470931d41a374508a7 $ + * + */ + bool Encrypt(std::vector const &vchText, ecies_secure_t &cryptex) + { + size_t length = vchText.size(); + size_t envelope_length, block_length, key_length; + if ((key_length = EVP_CIPHER_key_length(ECIES_CIPHER)) * 2 > SHA512_DIGEST_LENGTH) { +#ifdef DEBUG_ECIES + printf("The key derivation method will not produce enough envelope key material for the chosen ciphers. {envelope = %i / required = %zu}\n", + SHA512_DIGEST_LENGTH / 8, (key_length * 2) / 8); +#endif + return false; + } + + // Create the ephemeral key used specifically for this block of data. + EC_KEY *ephemeral; + if (!(ephemeral = EC_KEY_new())) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to generate the ephemeral key.\n"); +#endif + return false; + } else { + const EC_GROUP *group = NULL; + if( !(group = EC_KEY_get0_group(pkey))) { +#ifdef DEBUG_ECIES + printf("An error occurred in EC_KEY_get0_group.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + if (EC_KEY_set_group(ephemeral, group) != 1) { +#ifdef DEBUG_ECIES + printf("EC_KEY_set_group failed.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + } + + if (EC_KEY_generate_key(ephemeral) != 1) { +#ifdef DEBUG_ECIES + printf("EC_KEY_generate_key failed.\n"); +#endif + return false; + } + + // Use the intersection of the provided keys to generate the envelope data used by the ciphers below. The ecies_key_derivation() function uses + // SHA 512 to ensure we have a sufficient amount of envelope key material and that the material created is sufficiently secure. + unsigned char envelope_key[SHA512_DIGEST_LENGTH]; + if (ECDH_compute_key(envelope_key, SHA512_DIGEST_LENGTH, + EC_KEY_get0_public_key(pkey), + ephemeral, + ecies_key_derivation) != SHA512_DIGEST_LENGTH) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to compute the envelope key.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + // Determine the envelope and block lengths so we can allocate a buffer for the result. + if ((block_length = EVP_CIPHER_block_size(ECIES_CIPHER)) == 0 || + block_length > EVP_MAX_BLOCK_LENGTH || + (envelope_length = EC_POINT_point2oct(EC_KEY_get0_group(ephemeral), EC_KEY_get0_public_key(ephemeral), + POINT_CONVERSION_COMPRESSED, NULL, 0, NULL)) == 0) { +#ifdef DEBUG_ECIES + printf("Invalid block or envelope length. {block = %zu / envelope = %zu}\n", block_length, envelope_length); +#endif + EC_KEY_free(ephemeral); + return false; + } + + // We use a conditional to pad the length if the input buffer is not evenly divisible by the block size. + cryptex.key = std::vector(envelope_length); + cryptex.mac = std::vector(EVP_MD_size(ECIES_HASHER)); + cryptex.orig = length; + cryptex.body = std::vector(length + (length % block_length ? (block_length - (length % block_length)) : 0)); + + // Store the public key portion of the ephemeral key. + if (EC_POINT_point2oct(EC_KEY_get0_group(ephemeral), + EC_KEY_get0_public_key(ephemeral), + POINT_CONVERSION_COMPRESSED, + cryptex.key.data(), envelope_length, + NULL) != envelope_length) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to record the public portion of the envelope key.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + // The envelope key has been stored so we no longer need to keep the keys around. + EC_KEY_free(ephemeral); + + unsigned char iv[EVP_MAX_IV_LENGTH], block[EVP_MAX_BLOCK_LENGTH]; + // For now we use an empty initialization vector. + memset(iv, 0, EVP_MAX_IV_LENGTH); + + // Setup the cipher context, the body length, and store a pointer to the body buffer location. + EVP_CIPHER_CTX cipher; + EVP_CIPHER_CTX_init(&cipher); + + unsigned char *body = cryptex.body.data(); + int body_length = cryptex.body.size(); + + // Initialize the cipher with the envelope key. + if (EVP_EncryptInit_ex(&cipher, ECIES_CIPHER, NULL, envelope_key, iv) != 1 || + EVP_CIPHER_CTX_set_padding(&cipher, 0) != 1 || + EVP_EncryptUpdate(&cipher, body, &body_length, vchText.data(), length - (length % block_length)) != 1) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to secure the data using the chosen symmetric cipher.\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + // Check whether all of the data was encrypted. If they don't match up, we either have a partial block remaining, or an error occurred. + if (body_length != (int)length) { + // Make sure all that remains is a partial block, and their wasn't an error. + if (length - body_length >= block_length) { +#ifdef DEBUG_ECIES + printf("Unable to secure the data using the chosen symmetric cipher.\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + // Copy the remaining data into our partial block buffer. The memset() call ensures any extra bytes will be zero'ed out. + memset(block, 0, EVP_MAX_BLOCK_LENGTH); + memcpy(block, vchText.data() + body_length, length - body_length); + + // Advance the body pointer to the location of the remaining space, and calculate just how much room is still available. + body += body_length; + if ((body_length = cryptex.body.size() - body_length) < 0) { +#ifdef DEBUG_ECIES + printf("The symmetric cipher overflowed!\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + // Pass the final partially filled data block into the cipher as a complete block. The padding will be removed during the decryption process. + else if (EVP_EncryptUpdate(&cipher, body, &body_length, block, block_length) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to secure the data using the chosen symmetric cipher\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + } + + // Advance the pointer, then use pointer arithmetic to calculate how much of the body buffer has been used. The complex logic is needed so that we get + // the correct status regardless of whether there was a partial data block. + body += body_length; + if ((body_length = cryptex.body.size() - (body - cryptex.body.data())) < 0) { +#ifdef DEBUG_ECIES + printf("The symmetric cipher overflowed!\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + else if (EVP_EncryptFinal_ex(&cipher, body, &body_length) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to secure the data using the chosen symmetric cipher.\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + EVP_CIPHER_CTX_cleanup(&cipher); + + // Generate an authenticated hash which can be used to validate the data during decryption. + HMAC_CTX hmac; + HMAC_CTX_init(&hmac); + unsigned int mac_length = cryptex.mac.size(); + + // At the moment we are generating the hash using encrypted data. At some point we may want to validate the original text instead. + if (HMAC_Init_ex(&hmac, envelope_key + key_length, key_length, ECIES_HASHER, NULL) != 1 || + HMAC_Update(&hmac, cryptex.body.data(), cryptex.body.size()) != 1 || + HMAC_Final(&hmac, cryptex.mac.data(), &mac_length) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to generate a data authentication code.\n"); +#endif + HMAC_CTX_cleanup(&hmac); + return false; + } + + HMAC_CTX_cleanup(&hmac); + return true; + } + + bool Decrypt(ecies_secure_t const &cryptex, std::vector &vchText ) + { + size_t key_length; + if ((key_length = EVP_CIPHER_key_length(ECIES_CIPHER)) * 2 > SHA512_DIGEST_LENGTH) { +#ifdef DEBUG_ECIES + printf("The key derivation method will not produce enough envelope key material for the chosen ciphers. {envelope = %i / required = %zu}\n", + SHA512_DIGEST_LENGTH / 8, (key_length * 2) / 8); +#endif + return false; + } + + // Create the ephemeral key used specifically for this block of data. + EC_KEY *ephemeral; + if (!(ephemeral = EC_KEY_new())) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to generate the ephemeral key.\n"); +#endif + return false; + } else { + const EC_GROUP *group = NULL; + if( !(group = EC_KEY_get0_group(pkey))) { +#ifdef DEBUG_ECIES + printf("An error occurred in EC_KEY_get0_group.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + if (EC_KEY_set_group(ephemeral, group) != 1) { +#ifdef DEBUG_ECIES + printf("EC_KEY_set_group failed.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + EC_POINT *point = NULL; + if (!(point = EC_POINT_new(group))) { +#ifdef DEBUG_ECIES + printf("EC_POINT_new failed.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + if (EC_POINT_oct2point(group, point, cryptex.key.data(), cryptex.key.size(), NULL) != 1) { +#ifdef DEBUG_ECIES + printf("EC_POINT_oct2point failed.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + if (EC_KEY_set_public_key(ephemeral, point) != 1) { +#ifdef DEBUG_ECIES + printf("EC_KEY_set_public_key failed.\n"); +#endif + EC_POINT_free(point); + EC_KEY_free(ephemeral); + return false; + } + EC_POINT_free(point); + } + + if (EC_KEY_check_key(ephemeral) != 1) { +#ifdef DEBUG_ECIES + printf("EC_KEY_check_key ephemeral failed.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + // Use the intersection of the provided keys to generate the envelope data used by the ciphers below. The ecies_key_derivation() function uses + // SHA 512 to ensure we have a sufficient amount of envelope key material and that the material created is sufficiently secure. + unsigned char envelope_key[SHA512_DIGEST_LENGTH]; + if (ECDH_compute_key(envelope_key, SHA512_DIGEST_LENGTH, + EC_KEY_get0_public_key(ephemeral), + pkey, + ecies_key_derivation) != SHA512_DIGEST_LENGTH) { +#ifdef DEBUG_ECIES + printf("An error occurred while trying to compute the envelope key.\n"); +#endif + EC_KEY_free(ephemeral); + return false; + } + + // The envelope key material has been extracted, so we no longer need the user and ephemeral keys. + EC_KEY_free(ephemeral); + + // Use the authenticated hash of the ciphered data to ensure it was not modified after being encrypted. + HMAC_CTX hmac; + HMAC_CTX_init(&hmac); + unsigned int mac_length = EVP_MAX_MD_SIZE; + unsigned char md[EVP_MAX_MD_SIZE]; + + // At the moment we are generating the hash using encrypted data. At some point we may want to validate the original text instead. + if (HMAC_Init_ex(&hmac, envelope_key + key_length, key_length, ECIES_HASHER, NULL) != 1 || + HMAC_Update(&hmac, cryptex.body.data(), cryptex.body.size()) != 1 || + HMAC_Final(&hmac, md, &mac_length) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to generate a data authentication code.\n"); +#endif + HMAC_CTX_cleanup(&hmac); + return false; + } + + HMAC_CTX_cleanup(&hmac); + + // We can use the generated hash to ensure the encrypted data was not altered after being encrypted. + if (mac_length != cryptex.mac.size() || memcmp(md, cryptex.mac.data(), mac_length)) { +#ifdef DEBUG_ECIES + printf("The authentication code was invalid! The ciphered data has been corrupted!\n"); +#endif + return NULL; + } + + // Create a buffer to hold the result. + int output_length = cryptex.body.size(); + vchText.resize(output_length+1); + unsigned char *block, *output; + block = output = vchText.data(); + + unsigned char iv[EVP_MAX_IV_LENGTH]; + // For now we use an empty initialization vector. We also clear out the result buffer just to be on the safe side. + memset(iv, 0, EVP_MAX_IV_LENGTH); + memset(output, 0, output_length + 1); + + // Setup the cipher context, the body length, and store a pointer to the body buffer location. + EVP_CIPHER_CTX cipher; + EVP_CIPHER_CTX_init(&cipher); + + // Decrypt the data using the chosen symmetric cipher. + if (EVP_DecryptInit_ex(&cipher, ECIES_CIPHER, NULL, envelope_key, iv) != 1 || + EVP_CIPHER_CTX_set_padding(&cipher, 0) != 1 || + EVP_DecryptUpdate(&cipher, block, &output_length, cryptex.body.data(), cryptex.body.size()) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to decrypt the data using the chosen symmetric cipher.\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + block += output_length; + if ((output_length = cryptex.body.size() - output_length) != 0) { +#ifdef DEBUG_ECIES + printf("The symmetric cipher failed to properly decrypt the correct amount of data!\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + if (EVP_DecryptFinal_ex(&cipher, block, &output_length) != 1) { +#ifdef DEBUG_ECIES + printf("Unable to decrypt the data using the chosen symmetric cipher.\n"); +#endif + EVP_CIPHER_CTX_cleanup(&cipher); + return false; + } + + EVP_CIPHER_CTX_cleanup(&cipher); + + vchText.resize(cryptex.orig); + return true; + } }; }; // end of anonymous namespace @@ -340,6 +717,15 @@ bool CKey::SignCompact(const uint256 &hash, std::vector& vchSig) return true; } +bool CKey::Decrypt(ecies_secure_t const &cryptex, std::vector &vchText ) +{ + if (!fValid) + return false; + CECKey key; + key.SetSecretBytes(vch); + return key.Decrypt(cryptex, vchText); +} + bool CPubKey::Verify(const uint256 &hash, const std::vector& vchSig) const { if (!IsValid()) return false; @@ -394,3 +780,14 @@ bool CPubKey::Decompress() { key.GetPubKey(*this, false); return true; } + +bool CPubKey::Encrypt(std::vector const &vchText, ecies_secure_t &cryptex) +{ + if (!IsValid()) + return false; + CECKey key; + if (!key.SetPubKey(*this)) + return false; + return key.Encrypt(vchText, cryptex); +} + diff --git a/src/key.h b/src/key.h index ce469ad2..5b8fda63 100644 --- a/src/key.h +++ b/src/key.h @@ -36,6 +36,8 @@ public: CScriptID(const uint160 &in) : uint160(in) { } }; +struct ecies_secure_t; + /** An encapsulated public key. */ class CPubKey { private: @@ -161,6 +163,9 @@ public: // Turn this public key into an uncompressed public key. bool Decompress(); + + // Encrypt with public key + bool Encrypt(std::vector const &vchText, ecies_secure_t &cryptex); }; @@ -251,6 +256,30 @@ public: // 0x1D = second key with even y, 0x1E = second key with odd y, // add 0x04 for compressed keys. bool SignCompact(const uint256 &hash, std::vector& vchSig) const; + + bool Decrypt(ecies_secure_t const &cryptex, std::vector &vchText ); +}; + +/** + * @file /cryptron/ecies.h + * + * @brief ECIES module functions. + * + * $Author: Ladar Levison $ + * $Website: http://lavabit.com $ + * $Date: 2010/08/06 06:02:03 $ + * $Revision: a51931d0f81f6abe29ca91470931d41a374508a7 $ + * + */ + +#define ECIES_CIPHER EVP_aes_256_cbc() +#define ECIES_HASHER EVP_sha512() + +struct ecies_secure_t { + std::vector key; + std::vector mac; + size_t orig; + std::vector body; }; #endif diff --git a/src/twister.cpp b/src/twister.cpp index 1bc24c94..7b347c89 100644 --- a/src/twister.cpp +++ b/src/twister.cpp @@ -345,6 +345,31 @@ void ThreadSessionAlerts() } } +void encryptDecryptTest() +{ + CKey key1, key2; + key1.MakeNewKey(true); + key2.MakeNewKey(true); + + string sTextIn("Encrypted with public key, decrypted with private key"); + std::vector textIn(sTextIn.begin(), sTextIn.end()); + ecies_secure_t sec; + + bool encrypted = key1.GetPubKey().Encrypt(textIn, sec); + printf("encrypted = %d [key %d, mac %d, orig %d, body %d]\n", encrypted, + sec.key.size(), sec.mac.size(), sec.orig, sec.body.size()); + + std::vector textOut; + bool decrypt1 = key1.Decrypt(sec, textOut); + printf("decrypt1 = %d\n", decrypt1); + if( decrypt1 ) { + string s((char *)textOut.data(), textOut.size()); + printf("textOut = '%s'\n", s.c_str()); + } + + bool decrypt2 = key2.Decrypt(sec, textOut); + printf("decrypt2 = %d\n", decrypt2); +} void startSessionTorrent(boost::thread_group& threadGroup) { @@ -355,6 +380,8 @@ void startSessionTorrent(boost::thread_group& threadGroup) threadGroup.create_thread(boost::bind(&ThreadWaitExtIP)); threadGroup.create_thread(boost::bind(&ThreadMaintainDHTNodes)); threadGroup.create_thread(boost::bind(&ThreadSessionAlerts)); + + encryptDecryptTest(); } void stopSessionTorrent()