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implementation of HMAC-MD5-128

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orignal 2014-01-23 13:03:37 -05:00
parent 6385f4554e
commit d7d3fcef94
1 changed files with 60 additions and 0 deletions
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hmac.h Normal file
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#ifndef HMAC_H__
#define HMAC_H__
#include <inttypes.h>
#include <string.h>
#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
#include <cryptopp/md5.h>
namespace i2p
{
namespace crypto
{
const uint64_t IPAD = 0x3636363636363636;
const uint64_t OPAD = 0x5C5C5C5C5C5C5C5C;
inline void HMACMD5Digest (uint8_t * msg, size_t len, uint8_t * key, uint8_t * digest)
// key is 32 bytes
// digest is 16 bytes
// block size is 64 bytes
{
size_t totalLen = len + 64 + 32;
uint8_t * buf = new uint8_t[totalLen]; // TODO: reuse buffers
// ikeypad
((uint64_t *)buf)[0] = ((uint64_t *)key)[0] ^ IPAD;
((uint64_t *)buf)[1] = ((uint64_t *)key)[1] ^ IPAD;
((uint64_t *)buf)[2] = ((uint64_t *)key)[2] ^ IPAD;
((uint64_t *)buf)[3] = ((uint64_t *)key)[3] ^ IPAD;
((uint64_t *)buf)[4] = IPAD;
((uint64_t *)buf)[5] = IPAD;
((uint64_t *)buf)[6] = IPAD;
((uint64_t *)buf)[7] = IPAD;
// concatenate with msg
memcpy (buf + 64, msg, len);
// calculate first hash
uint8_t hash[16]; // MD5
CryptoPP::Weak1::MD5().CalculateDigest (hash, buf, len + 64);
// okeypad
((uint64_t *)buf)[0] = ((uint64_t *)key)[0] ^ OPAD;
((uint64_t *)buf)[1] = ((uint64_t *)key)[1] ^ OPAD;
((uint64_t *)buf)[2] = ((uint64_t *)key)[2] ^ OPAD;
((uint64_t *)buf)[3] = ((uint64_t *)key)[3] ^ OPAD;
((uint64_t *)buf)[4] = OPAD;
((uint64_t *)buf)[5] = OPAD;
((uint64_t *)buf)[6] = OPAD;
((uint64_t *)buf)[7] = OPAD;
// copy first hash after okeypad
memcpy (buf + 64, hash, 16);
// fill next 16 bytes with zeros (first hash size assumed 32 bytes in I2P)
memset (buf + 72, 0, 16);
// calculate digest
CryptoPP::Weak1::MD5().CalculateDigest (digest, buf, totalLen);
delete[] buf;
}
}
}
#endif