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https://github.com/shadps4-emu/ext-cryptopp.git
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97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
// hkdf.h - written and placed in public domain by Jeffrey Walton. Copyright assigned to Crypto++ project
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#ifndef CRYPTOPP_HASH_KEY_DERIVATION_FUNCTION_H
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#define CRYPTOPP_HASH_KEY_DERIVATION_FUNCTION_H
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#include "cryptlib.h"
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#include "hmac.h"
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#include "hrtimer.h"
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#include "secblock.h"
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#include <cstring>
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#if GCC_DIAGNOSTIC_AWARE
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# pragma GCC diagnostic push
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# pragma GCC diagnostic ignored "-Wunused-variable"
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#endif
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NAMESPACE_BEGIN(CryptoPP)
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//! abstract base class for key derivation function
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class KeyDerivationFunction
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{
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public:
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virtual size_t MaxDerivedKeyLength() const =0;
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virtual bool UsesContext() const =0;
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//! derive key from secret
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virtual unsigned int DeriveKey(byte *derived, size_t derivedLen, const byte *secret, size_t secretLen, const byte *salt, size_t saltLen, const byte* context=NULL, size_t contextLen=0) const =0;
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// If salt is missing, then use the NULL vector. The length depends on the Hash function.
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static const byte s_NullVector[64];
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};
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const byte KeyDerivationFunction::s_NullVector[64] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
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//! General, multipurpose KDF from RFC 5869. T should be a HashTransformation class
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//! https://eprint.iacr.org/2010/264 and https://tools.ietf.org/html/rfc5869
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template <class T>
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class CRYPTOPP_DLL HKDF : public KeyDerivationFunction
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{
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public:
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size_t MaxDerivedKeyLength() const {return static_cast<size_t>(T::DIGESTSIZE) * 255;}
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bool UsesContext() const {return true;}
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unsigned int DeriveKey(byte *derived, size_t derivedLen, const byte *secret, size_t secretLen, const byte *salt, size_t saltLen, const byte* context, size_t contextLen) const;
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};
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template <class T>
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unsigned int HKDF<T>::DeriveKey(byte *derived, size_t derivedLen, const byte *secret, size_t secretLen, const byte *salt, size_t saltLen, const byte* context, size_t contextLen) const
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{
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static const size_t DIGEST_SIZE = static_cast<size_t>(T::DIGESTSIZE);
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CRYPTOPP_COMPILE_ASSERT(DIGEST_SIZE <= COUNTOF(s_NullVector));
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const unsigned int req = static_cast<unsigned int>(derivedLen);
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assert(secret && secretLen);
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assert(derived && derivedLen);
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assert(derivedLen <= MaxDerivedKeyLength());
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if(derivedLen > MaxDerivedKeyLength())
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throw InvalidArgument("HKDF: derivedLen must be less than or equal to MaxDerivedKeyLength");
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HMAC<T> hmac;
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FixedSizeSecBlock<byte, DIGEST_SIZE> prk, buffer;
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// Extract
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const byte* key = (salt ? salt : s_NullVector);
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const size_t klen = (salt ? saltLen : DIGEST_SIZE);
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hmac.SetKey(key, klen);
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hmac.CalculateDigest(prk, secret, secretLen);
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// Expand
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hmac.SetKey(prk.data(), prk.size());
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byte block = 0;
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while (derivedLen > 0)
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{
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if(block++) {hmac.Update(buffer, buffer.size());}
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if(context && contextLen) {hmac.Update(context, contextLen);}
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hmac.CalculateDigest(buffer, &block, 1);
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size_t segmentLen = STDMIN(derivedLen, DIGEST_SIZE);
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std::memcpy(derived, buffer, segmentLen);
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derived += segmentLen;
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derivedLen -= segmentLen;
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}
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return req;
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}
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NAMESPACE_END
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#if GCC_DIAGNOSTIC_AWARE
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# pragma GCC diagnostic pop
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#endif
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#endif // CRYPTOPP_HASH_KEY_DERIVATION_FUNCTION_H
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