SHA3
Documentation |
#include <cryptopp/sha3.h>
|
SHA3 is the Permutation-Based Hash and Extendable-Output Functions and specified in FIPS 202. The standard provides SHA3-224, SHA3-256, SHA3-384 and SHA3-512. Crypto++ provides all hashes from FIPS 202.
All Crypto++ hashes derive from HashTransformation
. The base class provides functions like Update
, Final
and Verify
. You can swap-in any hash for any other hash in your program.
Sample Programs
There are five sample programs. The first prints information about the hash. The second creates a hash using SHA3-256 class. The third creates a hash using a pipeline. The fourth and fifth examples show how to verify an existing digest.
The examples below use SHA3-256, but you can swap-in any hash function, like PanamaHash or SM3.
The first example dumps the name, digest size and internal block size of the hash.
#include "cryptlib.h" #include "sha3.h" #include <iostream> int main (int argc, char* argv[]) { using namespace CryptoPP; SHA3_256 hash; std::cout << "Name: " << hash.AlgorithmName() << std::endl; std::cout << "Digest size: " << hash.DigestSize() << std::endl; std::cout << "Block size: " << hash.BlockSize() << std::endl; return 0; }
Running the program results in the following. In general you should use DigestSize
and avoid BlockSize
. BlockSize
is usually not required by a program. In the case of SHA3 the block size is the rate r
.
$ ./test.exe Name: SHA3-256 Digest size: 32 Block size: 136
The second example creates a hash using the hash object and member functions. You add data using Update
and you calculate the hash using Final
. Calling Final
resets the hash so you don't need to do it manually.
using namespace CryptoPP; HexEncoder encoder(new FileSink(std::cout)); std::string msg = "Yoda said, Do or do not. There is no try."; std::string digest; SHA3_256 hash; hash.Update((const byte*)msg.data(), msg.size()); digest.resize(hash.DigestSize()); hash.Final((byte*)&digest[0]); std::cout << "Message: " << msg << std::endl; std::cout << "Digest: "; StringSource(digest, true, new Redirector(encoder)); std::cout << std::endl;
Running the program results in the following.
$ ./test.exe Message: Yoda said, Do or do not. There is no try. Digest: 18CEA61486D217DCDC19246FA28BBD32660CEC3771442B5C2AB93271D32B2797
You can also obtain a truncated hash rather than the full hash using TruncatedFinal
.
std::cout << "Message: " << msg << std::endl; hash.Update((const byte*)msg.data(), msg.size()); digest.resize(hash.DigestSize()/2); hash.TruncatedFinal((byte*)&digest[0], digest.size()); std::cout << "Digest: "; StringSource(digest, true, new Redirector(encoder)); std::cout << std::endl;
The program produces the following result.
$ ./test.exe Message: Yoda said, Do or do not. There is no try. Digest: 18CEA61486D217DCDC19246FA28BBD32
Using a pipeline produces the same result. It relieves you of calling Update
and Final manually. The code also uses a HashFilter
, which has its own wiki page at HashFilter.
std::string msg = "Yoda said, Do or do not. There is no try."; std::string digest; StringSource(msg, true, new HashFilter(hash, new StringSink(digest))); std::cout << "Message: " << msg << std::endl; std::cout << "Digest: "; StringSource(digest, true, new Redirector(encoder)); std::cout << std::endl;
Running the program results in the following.
$ ./test.exe Message: Yoda said, Do or do not. There is no try. Digest: 18CEA61486D217DCDC19246FA28BBD32660CEC3771442B5C2AB93271D32B2797
The fourth program verifies an existing hash using the hash object. Notice the program proceeds as if the hash is going to be calculated. But rather than calling Final
to retrieve the hash, Verify
is called to verify the existing hash.
SHA3_256 hash; hash.Update((const byte*)msg.data(), msg.size()); bool verified = hash.Verify((const byte*)digest.data()); if (verified == true) std::cout << "Verified hash over message" << std::endl; else std::cout << "Failed to verify hash over message" << std::endl;
The final program verifies an existing hash using a pipeline. The code uses a HashVerificationFilter
, which has its own wiki page at HashVerificationFilter.
bool result; StringSource(digest+msg, true, new HashVerificationFilter(hash, new ArraySink((byte*)&result, sizeof(result)))); if (result == true) std::cout << "Verified hash over message" << std::endl; else std::cout << "Failed to verify hash over message" << std::endl;
Running the program results in the following output.
$ ./test.exe Message: Yoda said, Do or do not. There is no try. Digest: 18CEA61486D217DCDC19246FA28BBD32660CEC3771442B5C2AB93271D32B2797 Verified hash over message
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