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///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
#include "gsCrypt.h"
#include "gsLargeInt.h"
#include "gsSHA1.h"
// **Please refer to gsCrypt.h for public interface functions**
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
#ifdef GS_CRYPT_RSA_ES_OAEP
static gsi_i32 gsCryptRSAOAEPEncryptBuffer(const gsCryptRSAKey *publicKey, const unsigned char *plainText, gsi_u32 len, unsigned char buffer[GS_CRYPT_RSA_BYTE_SIZE]);
static gsi_i32 gsCryptRSAOAEPDecryptBuffer(const gsCryptRSAKey *privateKey, const unsigned char cipherText[GS_CRYPT_RSA_BYTE_SIZE], unsigned char *plainText, gsi_u32 *lenout);
static void gsiCryptRSAGenerateSeed(unsigned char *buffer, gsi_u32 len);
static gsi_bool gsiCryptRSAMaskData(unsigned char *data, gsi_u32 len, const unsigned char *maskSeed, gsi_u32 maskLen);
#else
static gsi_i32 gsCryptRSAPKCS1EncryptBuffer(const gsCryptRSAKey *publicKey, const unsigned char *plainText, gsi_u32 len, unsigned char buffer[GS_CRYPT_RSA_BYTE_SIZE]);
static gsi_i32 gsCryptRSAPKCS1DecryptBuffer(const gsCryptRSAKey *privateKey, const unsigned char ciperText[GS_CRYPT_RSA_BYTE_SIZE], unsigned char *plainTextOut, gsi_u32 *lenOut);
static void gsiCryptRSAGeneratePad(unsigned char *buffer, gsi_u32 len);
#endif
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
#ifdef GS_CRYPT_RSA_ES_OAEP
// generate a random seed for OAEP
void gsiCryptRSAGenerateSeed(unsigned char *buffer, gsi_u32 len)
{
unsigned int i=0;
Util_RandSeed(current_time());
for (i=0; i < len; i++)
{
//buffer[i] = 0x0c;
buffer[i] = (unsigned char)(Util_RandInt(0x00, 0xFF)+1);
GS_ASSERT(buffer[i] != 0x00);
}
}
// PKCS#1 v2.1, B.2.1 MGF1, mask generation function
// modification: generates mask and applies in place
gsi_bool gsiCryptRSAMaskData(unsigned char *data, gsi_u32 dataLen, const unsigned char* seed, gsi_u32 seedLen)
{
int i=0;
int k=0;
// The datablock may be used as the seed
unsigned char hashValue[GS_CRYPT_HASHSIZE]; // in integer form, NOT HEXSTRING
// seed should never be larger than the data block size (but it may be less)
if (seedLen > GS_CRYPT_RSA_DATABLOCKSIZE)
return gsi_false;
for (i=0; (gsi_u32)i<dataLen;i+=GS_CRYPT_HASHSIZE)
{
// Perform the hash
#if (GS_CRYPT_HASHSIZE==GS_CRYPT_MD5_HASHSIZE)
{
gsi_u32 temp=0;
// concatenate byte value of i onto seed
char seedPlusIter[GS_CRYPT_RSA_DATABLOCKSIZE+4]; // seed||i
char hashHexStr[GS_CRYPT_RSA_DATABLOCKSIZE*2+1]; // hexstr of hash "A1" rather than 0xA1
memcpy(&seedPlusIter[0], seed, seedLen);
seedPlusIter[GS_CRYPT_RSA_DATABLOCKSIZE+0] = 0x00;
seedPlusIter[GS_CRYPT_RSA_DATABLOCKSIZE+1] = 0x00;
seedPlusIter[GS_CRYPT_RSA_DATABLOCKSIZE+2] = 0x00;
seedPlusIter[GS_CRYPT_RSA_DATABLOCKSIZE+3] = (gsi_u8)(i/GS_CRYPT_HASHSIZE);
MD5Digest(seedPlusIter, seedLen+sizeof(gsi_u32), hashHexStr);
// convert from hexstr to integer form
for(k=0; k<seedLen+sizeof(gsi_u32))
{
gsi_u32 temp;
temp = sscanf(&hashHexStr[k*2], "%02X", &temp);
hashValue[k] = (gsi_u8)temp;
}
}
#elif (GS_CRYPT_HASHSIZE==GS_CRYPT_SHA1_HASHSIZE)
{
gsi_u8 counter[4] = { 0x00,0x00,0x00,0x00 };
SHA1Context sha;
counter[3] = (gsi_u8)(i/GS_CRYPT_HASHSIZE); // ensure little endian int
SHA1Reset(&sha);
SHA1Input(&sha, (const unsigned char*)seed, seedLen);
SHA1Input(&sha, counter, 4);
SHA1Result(&sha, hashValue);
}
#endif
// apply the mask to data
for (k=0; k<GS_CRYPT_HASHSIZE; k++)
{
if ((gsi_u32)(i+k) >= dataLen)
return gsi_true;
data[i+k] ^= (gsi_u8)hashValue[k];
}
}
return gsi_true;
}
#else
// generate a random pad for PKCS1
// [0x01 - 0xFF]
void gsiCryptRSAGeneratePad(unsigned char *buffer, gsi_u32 len)
{
unsigned int i=0;
Util_RandSeed(current_time());
for (i=0; i < len; i++)
{
#if defined(GS_CRYPT_NO_RANDOM)
#pragma message("GS_CRYPT_NO_RANDOM defined, SSL is NOT SECURE!!!!\r\n")
buffer[i] = 0x0c;
#else
buffer[i] = (unsigned char)(Util_RandInt(0x00, 0xFF)+1);
#endif
GS_ASSERT(buffer[i] != 0x00);
}
}
#endif
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// RSA Packet = encrypt(lhash, pad, 0x01, plainText)
// lhash is constant, since labels are not supported
// pad is variable length, depending on plainText length
gsi_i32 gsCryptRSAEncryptBuffer(const gsCryptRSAKey *publicKey, const unsigned char *plainText, gsi_u32 len, unsigned char buffer[GS_CRYPT_RSA_BYTE_SIZE])
{
#ifdef GS_CRYPT_RSA_ES_OAEP
return gsCryptRSAOAEPEncryptBuffer(publicKey, plainText, len, buffer);
#else
return gsCryptRSAPKCS1EncryptBuffer(publicKey, plainText, len, buffer);
#endif
}
#ifdef GS_CRYPT_RSA_ES_OAEP
gsi_i32 gsCryptRSAOAEPEncryptBuffer(const gsCryptRSAKey *publicKey, const unsigned char *plainText, gsi_u32 len, unsigned char buffer[GS_CRYPT_RSA_BYTE_SIZE])
{
gsLargeInt_t lintRSAPacket;
gsCryptRSAOAEPPacket* packet = (gsCryptRSAOAEPPacket*)lintRSAPacket.mData;
#if (GS_CRYPT_HASHSIZE==GS_CRYPT_MD5_HASHSIZE)
const gsi_u8 lhash[GS_CRYPT_HASHSIZE] = {0xd4,0x1d,0xd4,0x1d,0x8c,0xd9,0x8f,0x00,0xb2,0x04,0xe9,0x80,0x09,0x98,0xec,0xf8,0x42,0x7e}; // hash of ""
#else
const gsi_u8 lhash[GS_CRYPT_HASHSIZE] = {0xda,0x39,0xa3,0xee,0x5e,0x6b,0x4b,0x0d,0x32,0x55,0xbf,0xef,0x95,0x60,0x18,0x90,0xaf,0xd8,0x07,0x09}; // hash of ""
#endif
const unsigned int maxPlainTextLen = GS_CRYPT_RSA_BYTE_SIZE-2*GS_CRYPT_HASHSIZE-2;
const unsigned int padSize = maxPlainTextLen-len;
// The steps below are taken from PKCS#1, section 7.1.1 "Encryption Operation"
// 1. check length
if (len > maxPlainTextLen)
return -1;
// 2. EME-OAEP encoding (pad & pad format)
// a. precalculated above (const lhash)
// b. create pad
// c. concatenate hash+pad+0x01+plainText
memcpy(packet->maskedData, lhash, GS_CRYPT_HASHSIZE);
memset(&packet->maskedData[GS_CRYPT_HASHSIZE], 0, padSize); // pad with zero bytes
packet->maskedData[GS_CRYPT_HASHSIZE+padSize] = 0x01; // RSA encoding format ID (EME-OAEP)
memcpy(&packet->maskedData[GS_CRYPT_HASHSIZE+padSize+1], plainText, len);
// d. generate random seed (seed isn't masked until h.)
gsiCryptRSAGenerateSeed(packet->maskedSeed, GS_CRYPT_HASHSIZE);
// e. use (still unmasked) seed to generate a mask for the datablock
// f. apply it with xor
gsiCryptRSAMaskData(packet->maskedData, GS_CRYPT_RSA_DATABLOCKSIZE, packet->maskedSeed, GS_CRYPT_HASHSIZE);
// g. use the masked datablock to generate a mask for the seed
// h. apply it with xor
gsiCryptRSAMaskData(packet->maskedSeed, GS_CRYPT_HASHSIZE, packet->maskedData, GS_CRYPT_RSA_DATABLOCKSIZE);
// i. set first byte to 0x00
packet->headerByte = 0x00;
// 3. Encryptitize
/*
lintRSAPacket.mLength = GS_CRYPT_RSA_BYTE_SIZE/sizeof(gsi_u32);
gsLargeIntReverseBytes(&lintRSAPacket);
gsLargeIntPowerMod(&lintRSAPacket, &publicKey->exponent, &publicKey->modulus, &lintRSAPacket);
gsLargeIntReverseBytes(&lintRSAPacket);
// 4. return cipher text
memcpy(buffer, lintRSAPacket.mData, GS_CRYPT_RSA_BYTE_SIZE);
*/
GS_ASSERT(0); // Section above needs revision due to byte order issues
return 0;
}
#else
gsi_i32 gsCryptRSAPKCS1EncryptBuffer(const gsCryptRSAKey *publicKey, const unsigned char *plainText, gsi_u32 len, unsigned char buffer[GS_CRYPT_RSA_BYTE_SIZE])
{
gsi_u8 buf[GS_CRYPT_RSA_BYTE_SIZE];
gsCryptRSAPKCS1Packet* packet = (gsCryptRSAPKCS1Packet*)buf;
gsLargeInt_t lintRSAPacket;
if (len > (GS_CRYPT_RSA_BYTE_SIZE-11)) // 2 byte header, 8 byte pad minimum, 1 byte separator
return -1;
// form the packet
packet->headerByte[0] = 0x00;
packet->headerByte[1] = 0x02;
gsiCryptRSAGeneratePad(packet->data, GS_CRYPT_RSA_BYTE_SIZE-len-3);
packet->data[GS_CRYPT_RSA_BYTE_SIZE-len-3] = 0x00; // separator
memcpy(&packet->data[GS_CRYPT_RSA_BYTE_SIZE-len-3+1], plainText, len);
if (gsi_is_false(gsLargeIntSetFromMemoryStream(&lintRSAPacket, (const gsi_u8*)buf, GS_CRYPT_RSA_BYTE_SIZE)) ||
gsi_is_false(gsLargeIntPowerMod(&lintRSAPacket, &publicKey->exponent, &publicKey->modulus, &lintRSAPacket)) ||
gsi_is_false(gsLargeIntWriteToMemoryStream(&lintRSAPacket, buffer)) )
{
return -1;
}
return 0;
}
#endif
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
gsi_i32 gsCryptRSADecryptBuffer(const gsCryptRSAKey *privateKey, const unsigned char cipherText[GS_CRYPT_RSA_BYTE_SIZE], unsigned char *plainText, gsi_u32 *lenout)
{
#ifdef GS_CRYPT_RSA_ES_OAEP
return gsCryptRSAOAEPDecryptBuffer(privateKey, cipherText, plainText, lenout);
#else
return gsCryptRSAPKCS1DecryptBuffer(privateKey, cipherText, plainText, lenout);
#endif
}
// Since decryption requires the privatekey, it is usually done by the server.
// Decryption is also much slower than encryption.
// This is included here as a testing utility but should probably not be used in a game client.
#ifndef GS_CRYPT_RSA_ES_OAEP
static gsi_i32 gsCryptRSAPKCS1DecryptBuffer(const gsCryptRSAKey *privateKey, const unsigned char cipherText[GS_CRYPT_RSA_BYTE_SIZE], unsigned char *plainText, gsi_u32 *lenout)
{
int i=0;
char* temp;
gsLargeInt_t lintRSAPacket;
lintRSAPacket.mLength = GS_CRYPT_RSA_BYTE_SIZE/GS_LARGEINT_DIGIT_SIZE_BYTES;
memcpy(lintRSAPacket.mData, cipherText, GS_CRYPT_RSA_BYTE_SIZE);
if (gsi_is_false(gsLargeIntReverseBytes(&lintRSAPacket)) || // reverse from bytebuffer to lint format
gsi_is_false(gsLargeIntPowerMod(&lintRSAPacket, &privateKey->exponent, &privateKey->modulus, &lintRSAPacket)) ||
gsi_is_false(gsLargeIntReverseBytes(&lintRSAPacket)) // reverse back into a bytebuffer
)
{
return -1;
}
// check post exponentiation length
if (lintRSAPacket.mLength < (GS_CRYPT_RSA_BYTE_SIZE/GS_LARGEINT_DIGIT_SIZE_BYTES))
return -1;
// Check the packet for legality
// 1. first byte must be 0x00
// 2. send byte must be 0x02
// 3. pad must be at least 8 bytes and end with 0x00
// 4. payload must be at least 1 byte
temp = (char*)lintRSAPacket.mData;
if (temp[0] != 0x00)
return -1;
if (temp[1] != 0x02)
return -2;
// find the start of the data (first 0x00 byte after the 1st)
temp = (char*)lintRSAPacket.mData;
for (i=2; i<GS_CRYPT_RSA_BYTE_SIZE; i++)
{
if (temp[i] == 0)
break;
}
if (i < (2+8)) // 2 byte header, 8 byte minimum pad
return -3; // pad too small
if (i == GS_CRYPT_RSA_BYTE_SIZE)
return -4; // no payload
// the rest is the msg
memcpy(plainText, (temp+i+1), GS_CRYPT_RSA_BYTE_SIZE); // +1 to skip the 0x00
*lenout = (gsi_u32)(GS_CRYPT_RSA_BYTE_SIZE-(i+1)); // +1 to skip the 0x00
return 0;
}
#else
static gsi_i32 gsCryptRSAOAEPDecryptBuffer(const gsCryptRSAKey *privateKey, const unsigned char cipherText[GS_CRYPT_RSA_BYTE_SIZE], unsigned char *plainText, gsi_u32 *lenout)
{
int i=0;
gsLargeInt_t lintRSAPacket;
gsCryptRSAOAEPPacket* packet = (gsCryptRSAOAEPPacket*)lintRSAPacket.mData;
#if (GS_CRYPT_HASHSIZE==GS_CRYPT_MD5_HASHSIZE)
const gsi_u8 lhash[GS_CRYPT_HASHSIZE] = {0xd4,0x1d,0xd4,0x1d,0x8c,0xd9,0x8f,0x00,0xb2,0x04,0xe9,0x80,0x09,0x98,0xec,0xf8,0x42,0x7e}; // hash of ""
#else
const gsi_u8 lhash[GS_CRYPT_HASHSIZE] = {0xda,0x39,0xa3,0xee,0x5e,0x6b,0x4b,0x0d,0x32,0x55,0xbf,0xef,0x95,0x60,0x18,0x90,0xaf,0xd8,0x07,0x09}; // hash of ""
#endif
lintRSAPacket.mLength = GS_CRYPT_RSA_BYTE_SIZE/4;
memcpy(lintRSAPacket.mData, cipherText, GS_CRYPT_RSA_BYTE_SIZE);
gsLargeIntReverseBytes(&lintRSAPacket); // reverse from bytebuffer to lint format
gsLargeIntPowerMod(&lintRSAPacket, &privateKey->exponent, &privateKey->modulus, &lintRSAPacket);
gsLargeIntReverseBytes(&lintRSAPacket); // reverse back into a bytebuffer
// check post exponentiation length
if (lintRSAPacket.mLength < (GS_CRYPT_RSA_BYTE_SIZE/4))
return -1;
// Check the packet for legality
// 1. "un-mask" the maskedSeed, using the maskedData
gsiCryptRSAMaskData(packet->maskedSeed, GS_CRYPT_HASHSIZE, packet->maskedData, GS_CRYPT_RSA_DATABLOCKSIZE);
// 2. "un-mask" the maskedData, using the previously unmasked maskedSeed
gsiCryptRSAMaskData(packet->maskedData, GS_CRYPT_RSA_DATABLOCKSIZE, packet->maskedSeed, GS_CRYPT_HASHSIZE);
// 3. datablock = [lhash][0x00...][0x01][M]
if (0 != memcmp(packet->maskedData, lhash, GS_CRYPT_HASHSIZE))
return -2; // label has doesn't match (mismatched hash algorithms?)
i = 33;
while(i<GS_CRYPT_RSA_BYTE_SIZE && packet->maskedData[i] == 0x00)
i++; // may be zero bytes pad
if (i==GS_CRYPT_RSA_BYTE_SIZE || packet->maskedData[i] != 0x01)
return -3; // must be a 0x01 following the pad
i++;
if (i == GS_CRYPT_RSA_BYTE_SIZE)
return -4; // founnd the separator, but no message!
memcpy(plainText, &packet->maskedData[i], (size_t)(GS_CRYPT_RSA_DATABLOCKSIZE-i));
*lenout = (gsi_u32)(GS_CRYPT_RSA_DATABLOCKSIZE-i); // final length = blocksize - pad
return 0;
}
#endif
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
gsi_i32 gsCryptRSASignData(const gsCryptRSAKey *privateKey, const unsigned char *plainText, gsi_u32 plainTextLen, unsigned char *signedDataOut, gsi_u32 *lenOut)
{
const unsigned char * hash = NULL;
GSI_UNUSED(privateKey);
GSI_UNUSED(plainText);
GSI_UNUSED(plainTextLen);
GSI_UNUSED(signedDataOut);
GSI_UNUSED(lenOut);
// 1) hash data
// hash = MD5(plainText);
//GS_ASSERT(0); // not implemented yet
// 2) Sign
return gsCryptRSASignHash(privateKey, hash, GS_CRYPT_MD5_HASHSIZE, signedDataOut, lenOut);
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// The more usual use of RSA signatures
// Constructs a PKCS1 signature form of type { [0x00][0x01][0xFF..FF][0x00][hash oid][hash] } = RSA key length
gsi_i32 gsCryptRSASignHash(const gsCryptRSAKey *privateKey, const unsigned char *hash, gsi_u32 hashLen, unsigned char *signedDataOut, gsi_u32 *lenOut)
{
// Encode to PKCS1 signature form
gsi_u32 aKeyByteLength = privateKey->modulus.mLength * GS_LARGEINT_DIGIT_SIZE_BYTES; // key length in bytes
gsi_u32 aReservedLength = 3;
gsi_u32 anOidLen;
gsLargeInt_t dataToSign;
char * writeBuf = (char*)dataToSign.mData;
// Microsoft PKCS #1 headers for various hash algorithms.
gsi_u8 md5Header[18] = {0x30,0x20,0x30,0x0C,0x06,0x08,0x2A,0x86,0x48,0x86,0xF7,0x0D,0x02,0x05,0x05,0x00,0x04,0x10};
gsi_u8 sha1Header[15] = {0x30,0x21,0x30,0x09,0x06,0x05,0x2B,0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14};
if (hashLen == GS_CRYPT_MD5_HASHSIZE)
anOidLen = sizeof(md5Header);
else if (hashLen == GS_CRYPT_SHA1_HASHSIZE)
anOidLen = sizeof(sha1Header);
else
return -1; // hash algorithm could not be identified from hashLen
// Make sure the key is large enough to sign this hash
GS_ASSERT(hashLen + anOidLen + aReservedLength <= aKeyByteLength);
if (hashLen + anOidLen + aReservedLength > aKeyByteLength)
return -2; // key is too small or hash is too large
// fill in header bytes
writeBuf[0] = 0x00;
writeBuf[1] = 0x01;
// pad with 0xFF
memset(&writeBuf[2], 0xFF, aKeyByteLength - hashLen - anOidLen - aReservedLength);
// set a 0x00 at the end of the 0xFF pad
writeBuf[aKeyByteLength - hashLen - anOidLen - 1] = 0x00;
// copy in the oid
if (hashLen == GS_CRYPT_MD5_HASHSIZE)
memcpy(&writeBuf[aKeyByteLength-hashLen-anOidLen], md5Header, sizeof(md5Header));
else if (hashLen == GS_CRYPT_SHA1_HASHSIZE)
memcpy(&writeBuf[aKeyByteLength-hashLen-anOidLen], sha1Header, sizeof(sha1Header));
else
return -1; // should probably assert here
// copy in the hash
memcpy(&writeBuf[aKeyByteLength-hashLen], hash, hashLen);
// fix byte order for large int
dataToSign.mLength = privateKey->modulus.mLength;
gsLargeIntReverseBytes(&dataToSign);
// sign (a.k.a. encrypt)
gsLargeIntPowerMod(&dataToSign, &privateKey->exponent, &privateKey->modulus, &dataToSign);
// length of output data is always the length of the private key's modulus
GS_ASSERT(dataToSign.mLength == privateKey->modulus.mLength);
gsLargeIntReverseBytes(&dataToSign); // switch back to rawbuffer byte order
memcpy(signedDataOut, dataToSign.mData, aKeyByteLength);
*lenOut = aKeyByteLength;
return 0;
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// "data" is the text that was signed, encrypted or plaintext
// "sig" is the signature value attached to the msg (BIG-endian)
// Signature format:
// [ 0x00 0x01 0xFF ... 0x00 HashHeader Hash(Data) ]
gsi_i32 gsCryptRSAVerifySignedHash(const gsCryptRSAKey *publicKey, const unsigned char *hash, gsi_u32 hashLen, const unsigned char *sig, gsi_u32 sigLen)
{
gsLargeInt_t lintRSASignature;
gsi_u8* packet = (gsi_u8*)lintRSASignature.mData;
int i=0;
// Microsoft PKCS #1 headers for various hash algorithms.
gsi_u8 md5Header[18] = {0x30,0x20,0x30,0x0C,0x06,0x08,0x2A,0x86,0x48,0x86,0xF7,0x0D,0x02,0x05,0x05,0x00,0x04,0x10};
gsi_u8 sha1Header[15] = {0x30,0x21,0x30,0x09,0x06,0x05,0x2B,0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14};
// check parameters for common errors
if (hash==NULL || sig==NULL)
return -1;
if (sigLen != publicKey->modulus.mLength*GS_LARGEINT_DIGIT_SIZE_BYTES)
return -1;
if (hashLen != GS_CRYPT_MD5_HASHSIZE && hashLen != GS_CRYPT_SHA1_HASHSIZE)
return -1; // invalid hashsize
// "decrypt" the signature
lintRSASignature.mLength = (l_word)(sigLen / GS_LARGEINT_DIGIT_SIZE_BYTES);
memcpy(lintRSASignature.mData, sig, sigLen);
gsLargeIntReverseBytes(&lintRSASignature);
gsLargeIntPowerMod(&lintRSASignature, &publicKey->exponent, &publicKey->modulus, &lintRSASignature);
gsLargeIntReverseBytes(&lintRSASignature);
// Check format, first by 0x00, second byte 0x01
if (packet[0] != 0x00 || packet[1] != 0x01)
return -2;
// Loop through the 0xFF's
for (i=2; i<GS_CRYPT_RSA_BYTE_SIZE; i++)
{
if (packet[i] == 0x00)
break;
if (packet[i] != 0xFF)
return -3;
}
i++; // skip the 0x00 seperator byte
// Next should be the hash header (but we don't know which one!)
if ((i+sizeof(md5Header)+GS_CRYPT_MD5_HASHSIZE) == (lintRSASignature.mLength*GS_LARGEINT_DIGIT_SIZE_BYTES))
{
// MD5 Hash
// 1. verify header
if (0 != memcmp(md5Header, &packet[i], sizeof(md5Header)))
return -4;
i += sizeof(md5Header);
// 2. compare hashes
if (hashLen != GS_CRYPT_MD5_HASHSIZE)
return -5;
if (0 != memcmp(&packet[i], hash, GS_CRYPT_MD5_HASHSIZE))
return -5;
}
else if ((i+sizeof(sha1Header)+GS_CRYPT_SHA1_HASHSIZE) == (lintRSASignature.mLength*GS_LARGEINT_DIGIT_SIZE_BYTES))
{
// SHA1 Hash
// 1. verify header
if (0 != memcmp(sha1Header, &packet[i], sizeof(sha1Header)))
return -4;
i += sizeof(sha1Header);
// 2. compare hashes
if (hashLen != GS_CRYPT_SHA1_HASHSIZE)
return -5;
if (0 != memcmp(&packet[i], hash, GS_CRYPT_SHA1_HASHSIZE))
return -5;
}
else
return -4; // unsupported hash
// Signature valid!
return 0;
}
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