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514 bytes ECIES block

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orignal 2017-11-08 21:06:58 -05:00
parent 19a03c42a5
commit 1e75de9bb8
2 changed files with 11 additions and 9 deletions
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18
libi2pd/Crypto.cpp
View File

@ -385,10 +385,11 @@ namespace crypto
auto p = EC_POINT_new (curve);
EC_POINT_mul (curve, p, k, nullptr, nullptr, ctx);
BIGNUM * x = BN_CTX_get (ctx), * y = BN_CTX_get (ctx);
EC_POINT_get_affine_coordinates_GFp (curve, p, x, y, nullptr);
bn2buf (x, encrypted, len);
bn2buf (y, encrypted + len, len);
RAND_bytes (encrypted + 2*len, 256 - 2*len);
EC_POINT_get_affine_coordinates_GFp (curve, p, x, y, nullptr);
encrypted[0] = 0;
bn2buf (x, encrypted + 1, len);
bn2buf (y, encrypted + 1 + len, len);
RAND_bytes (encrypted + 1 + 2*len, 256 - 2*len);
// ecryption key and iv
EC_POINT_mul (curve, p, nullptr, key, k, ctx);
EC_POINT_get_affine_coordinates_GFp (curve, p, x, y, nullptr);
@ -402,10 +403,11 @@ namespace crypto
memcpy (m+33, data, 222);
SHA256 (m+33, 222, m+1);
// encrypt
encrypted[257] = 0;
CBCEncryption encryption;
encryption.SetKey (shared);
encryption.SetIV (iv);
encryption.Encrypt (m, 256, encrypted + 256);
encryption.Encrypt (m, 256, encrypted + 258);
EC_POINT_free (p);
BN_CTX_end (ctx);
}
@ -419,8 +421,8 @@ namespace crypto
int len = BN_num_bytes (q);
// point for shared secret
BIGNUM * x = BN_CTX_get (ctx), * y = BN_CTX_get (ctx);
BN_bin2bn (encrypted, len, x);
BN_bin2bn (encrypted + len, len, y);
BN_bin2bn (encrypted + 1, len, x);
BN_bin2bn (encrypted + 1 + len, len, y);
auto p = EC_POINT_new (curve);
if (EC_POINT_set_affine_coordinates_GFp (curve, p, x, y, nullptr))
{
@ -437,7 +439,7 @@ namespace crypto
CBCDecryption decryption;
decryption.SetKey (shared);
decryption.SetIV (iv);
decryption.Decrypt (encrypted + 256, 256, m);
decryption.Decrypt (encrypted + 258, 256, m);
// verify and copy
uint8_t hash[32];
SHA256 (m + 33, 222, hash);

2
libi2pd/Crypto.h
View File

@ -53,7 +53,7 @@ namespace crypto
void GenerateElGamalKeyPair (uint8_t * priv, uint8_t * pub);
// ECIES
void ECIESEncrypt (const EC_GROUP * curve, const EC_POINT * key, const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx); // 222 bytes data, 512 bytes encrypted
void ECIESEncrypt (const EC_GROUP * curve, const EC_POINT * key, const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx); // 222 bytes data, 514 bytes encrypted
bool ECIESDecrypt (const EC_GROUP * curve, const BIGNUM * key, const uint8_t * encrypted, uint8_t * data, BN_CTX * ctx);
void GenerateECIESKeyPair (const EC_GROUP * curve, BIGNUM *& priv, EC_POINT *& pub);