/** * Construct a SP800-90A Hash DRBG. * <p> * Minimum entropy requirement is the security strength requested. * </p> * @param digest source digest to use for DRB stream. * @param securityStrength security strength required (in bits) * @param entropySource source of entropy to use for seeding/reseeding. * @param personalizationString personalization string to distinguish this DRBG (may be null). * @param nonce nonce to further distinguish this DRBG (may be null). */ public HashSP800Drbg(IDigest digest, int securityStrength, IEntropySource entropySource, byte[] personalizationString, byte[] nonce) { if (securityStrength > DrbgUtilities.GetMaxSecurityStrength(digest)) { throw new ArgumentException("Requested security strength is not supported by the derivation function"); } if (entropySource.EntropySize < securityStrength) { throw new ArgumentException("Not enough entropy for security strength required"); } mDigest = digest; mEntropySource = entropySource; mSecurityStrength = securityStrength; mSeedLength = (int)seedlens[digest.AlgorithmName]; // 1. seed_material = entropy_input || nonce || personalization_string. // 2. seed = Hash_df (seed_material, seedlen). // 3. V = seed. // 4. C = Hash_df ((0x00 || V), seedlen). Comment: Preceed V with a byte // of zeros. // 5. reseed_counter = 1. // 6. Return V, C, and reseed_counter as the initial_working_state byte[] entropy = GetEntropy(); byte[] seedMaterial = Arrays.ConcatenateAll(entropy, nonce, personalizationString); byte[] seed = DrbgUtilities.HashDF(mDigest, seedMaterial, mSeedLength); mV = seed; byte[] subV = new byte[mV.Length + 1]; Array.Copy(mV, 0, subV, 1, mV.Length); mC = DrbgUtilities.HashDF(mDigest, subV, mSeedLength); mReseedCounter = 1; }
/** * Reseed the DRBG. * * @param additionalInput additional input to be added to the DRBG in this step. */ public void Reseed(byte[] additionalInput) { // 1. seed_material = 0x01 || V || entropy_input || additional_input. // // 2. seed = Hash_df (seed_material, seedlen). // // 3. V = seed. // // 4. C = Hash_df ((0x00 || V), seedlen). // // 5. reseed_counter = 1. // // 6. Return V, C, and reseed_counter for the new_working_state. // // Comment: Precede with a byte of all zeros. byte[] entropy = GetEntropy(); byte[] seedMaterial = Arrays.ConcatenateAll(ONE, mV, entropy, additionalInput); byte[] seed = DrbgUtilities.HashDF(mDigest, seedMaterial, mSeedLength); mV = seed; byte[] subV = new byte[mV.Length + 1]; subV[0] = 0x00; Array.Copy(mV, 0, subV, 1, mV.Length); mC = DrbgUtilities.HashDF(mDigest, subV, mSeedLength); mReseedCounter = 1; }