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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.

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package org.bouncycastle.crypto.prng.drbg;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.prng.EntropySource;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Hex;

/**
 * A SP800-90A CTR DRBG.
 */
public class CTRSP800DRBG
    implements SP80090DRBG
{
    private static final long       TDEA_RESEED_MAX = 1L << (32 - 1);
    private static final long       AES_RESEED_MAX = 1L << (48 - 1);
    private static final int        TDEA_MAX_BITS_REQUEST = 1 << (13 - 1);
    private static final int        AES_MAX_BITS_REQUEST = 1 << (19 - 1);

    private EntropySource          _entropySource;
    private BlockCipher           _engine;
    private int                   _keySizeInBits;
    private int                   _seedLength;
    private int                   _securityStrength;

    // internal state
    private byte[]                _Key;
    private byte[]                _V;
    private long                  _reseedCounter = 0;
    private boolean               _isTDEA = false;

    /**
     * Construct a SP800-90A CTR DRBG.
     * 

* Minimum entropy requirement is the security strength requested. *

* @param engine underlying block cipher to use to support DRBG * @param keySizeInBits size of the key to use with the block cipher. * @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 CTRSP800DRBG(BlockCipher engine, int keySizeInBits, int securityStrength, EntropySource entropySource, byte[] personalizationString, byte[] nonce) { _entropySource = entropySource; _engine = engine; _keySizeInBits = keySizeInBits; _securityStrength = securityStrength; _seedLength = keySizeInBits + engine.getBlockSize() * 8; _isTDEA = isTDEA(engine); if (securityStrength > 256) { throw new IllegalArgumentException("Requested security strength is not supported by the derivation function"); } if (getMaxSecurityStrength(engine, keySizeInBits) < securityStrength) { throw new IllegalArgumentException("Requested security strength is not supported by block cipher and key size"); } if (entropySource.entropySize() < securityStrength) { throw new IllegalArgumentException("Not enough entropy for security strength required"); } byte[] entropy = getEntropy(); // Get_entropy_input CTR_DRBG_Instantiate_algorithm(entropy, nonce, personalizationString); } private void CTR_DRBG_Instantiate_algorithm(byte[] entropy, byte[] nonce, byte[] personalisationString) { byte[] seedMaterial = Arrays.concatenate(entropy, nonce, personalisationString); byte[] seed = Block_Cipher_df(seedMaterial, _seedLength); int outlen = _engine.getBlockSize(); _Key = new byte[(_keySizeInBits + 7) / 8]; _V = new byte[outlen]; // _Key & _V are modified by this call CTR_DRBG_Update(seed, _Key, _V); _reseedCounter = 1; } private void CTR_DRBG_Update(byte[] seed, byte[] key, byte[] v) { byte[] temp = new byte[seed.length]; byte[] outputBlock = new byte[_engine.getBlockSize()]; int i=0; int outLen = _engine.getBlockSize(); _engine.init(true, new KeyParameter(expandKey(key))); while (i*outLen < seed.length) { addOneTo(v); _engine.processBlock(v, 0, outputBlock, 0); int bytesToCopy = ((temp.length - i * outLen) > outLen) ? outLen : (temp.length - i * outLen); System.arraycopy(outputBlock, 0, temp, i * outLen, bytesToCopy); ++i; } XOR(temp, seed, temp, 0); System.arraycopy(temp, 0, key, 0, key.length); System.arraycopy(temp, key.length, v, 0, v.length); } private void CTR_DRBG_Reseed_algorithm(byte[] additionalInput) { byte[] seedMaterial = Arrays.concatenate(getEntropy(), additionalInput); seedMaterial = Block_Cipher_df(seedMaterial, _seedLength); CTR_DRBG_Update(seedMaterial, _Key, _V); _reseedCounter = 1; } private void XOR(byte[] out, byte[] a, byte[] b, int bOff) { for (int i=0; i< out.length; i++) { out[i] = (byte)(a[i] ^ b[i+bOff]); } } private void addOneTo(byte[] longer) { int carry = 1; for (int i = 1; i <= longer.length; i++) // warning { int res = (longer[longer.length - i] & 0xff) + carry; carry = (res > 0xff) ? 1 : 0; longer[longer.length - i] = (byte)res; } } private byte[] getEntropy() { byte[] entropy = _entropySource.getEntropy(); if (entropy.length < (_securityStrength + 7) / 8) { throw new IllegalStateException("Insufficient entropy provided by entropy source"); } return entropy; } // -- Internal state migration --- private static final byte[] K_BITS = Hex.decode("000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"); // 1. If (number_of_bits_to_return > max_number_of_bits), then return an // ERROR_FLAG. // 2. L = len (input_string)/8. // 3. N = number_of_bits_to_return/8. // Comment: L is the bitstring represention of // the integer resulting from len (input_string)/8. // L shall be represented as a 32-bit integer. // // Comment : N is the bitstring represention of // the integer resulting from // number_of_bits_to_return/8. N shall be // represented as a 32-bit integer. // // 4. S = L || N || input_string || 0x80. // 5. While (len (S) mod outlen) // Comment : Pad S with zeros, if necessary. // 0, S = S || 0x00. // // Comment : Compute the starting value. // 6. temp = the Null string. // 7. i = 0. // 8. K = Leftmost keylen bits of 0x00010203...1D1E1F. // 9. While len (temp) < keylen + outlen, do // // IV = i || 0outlen - len (i). // // 9.1 // // temp = temp || BCC (K, (IV || S)). // // 9.2 // // i = i + 1. // // 9.3 // // Comment : i shall be represented as a 32-bit // integer, i.e., len (i) = 32. // // Comment: The 32-bit integer represenation of // i is padded with zeros to outlen bits. // // Comment: Compute the requested number of // bits. // // 10. K = Leftmost keylen bits of temp. // // 11. X = Next outlen bits of temp. // // 12. temp = the Null string. // // 13. While len (temp) < number_of_bits_to_return, do // // 13.1 X = Block_Encrypt (K, X). // // 13.2 temp = temp || X. // // 14. requested_bits = Leftmost number_of_bits_to_return of temp. // // 15. Return SUCCESS and requested_bits. private byte[] Block_Cipher_df(byte[] inputString, int bitLength) { int outLen = _engine.getBlockSize(); int L = inputString.length; // already in bytes int N = bitLength / 8; // 4 S = L || N || inputstring || 0x80 int sLen = 4 + 4 + L + 1; int blockLen = ((sLen + outLen - 1) / outLen) * outLen; byte[] S = new byte[blockLen]; copyIntToByteArray(S, L, 0); copyIntToByteArray(S, N, 4); System.arraycopy(inputString, 0, S, 8, L); S[8 + L] = (byte)0x80; // S already padded with zeros byte[] temp = new byte[_keySizeInBits / 8 + outLen]; byte[] bccOut = new byte[outLen]; byte[] IV = new byte[outLen]; int i = 0; byte[] K = new byte[_keySizeInBits / 8]; System.arraycopy(K_BITS, 0, K, 0, K.length); while (i*outLen*8 < _keySizeInBits + outLen *8) { copyIntToByteArray(IV, i, 0); BCC(bccOut, K, IV, S); int bytesToCopy = ((temp.length - i * outLen) > outLen) ? outLen : (temp.length - i * outLen); System.arraycopy(bccOut, 0, temp, i * outLen, bytesToCopy); ++i; } byte[] X = new byte[outLen]; System.arraycopy(temp, 0, K, 0, K.length); System.arraycopy(temp, K.length, X, 0, X.length); temp = new byte[bitLength / 2]; i = 0; _engine.init(true, new KeyParameter(expandKey(K))); while (i * outLen < temp.length) { _engine.processBlock(X, 0, X, 0); int bytesToCopy = ((temp.length - i * outLen) > outLen) ? outLen : (temp.length - i * outLen); System.arraycopy(X, 0, temp, i * outLen, bytesToCopy); i++; } return temp; } /* * 1. chaining_value = 0^outlen * . Comment: Set the first chaining value to outlen zeros. * 2. n = len (data)/outlen. * 3. Starting with the leftmost bits of data, split the data into n blocks of outlen bits * each, forming block(1) to block(n). * 4. For i = 1 to n do * 4.1 input_block = chaining_value ^ block(i) . * 4.2 chaining_value = Block_Encrypt (Key, input_block). * 5. output_block = chaining_value. * 6. Return output_block. */ private void BCC(byte[] bccOut, byte[] k, byte[] iV, byte[] data) { int outlen = _engine.getBlockSize(); byte[] chainingValue = new byte[outlen]; // initial values = 0 int n = data.length / outlen; byte[] inputBlock = new byte[outlen]; _engine.init(true, new KeyParameter(expandKey(k))); _engine.processBlock(iV, 0, chainingValue, 0); for (int i = 0; i < n; i++) { XOR(inputBlock, chainingValue, data, i*outlen); _engine.processBlock(inputBlock, 0, chainingValue, 0); } System.arraycopy(chainingValue, 0, bccOut, 0, bccOut.length); } private void copyIntToByteArray(byte[] buf, int value, int offSet) { buf[offSet + 0] = ((byte)(value >> 24)); buf[offSet + 1] = ((byte)(value >> 16)); buf[offSet + 2] = ((byte)(value >> 8)); buf[offSet + 3] = ((byte)(value)); } /** * Return the block size (in bits) of the DRBG. * * @return the number of bits produced on each internal round of the DRBG. */ public int getBlockSize() { return _V.length * 8; } /** * Populate a passed in array with random data. * * @param output output array for generated bits. * @param additionalInput additional input to be added to the DRBG in this step. * @param predictionResistant true if a reseed should be forced, false otherwise. * * @return number of bits generated, -1 if a reseed required. */ public int generate(byte[] output, byte[] additionalInput, boolean predictionResistant) { if (_isTDEA) { if (_reseedCounter > TDEA_RESEED_MAX) { return -1; } if (Utils.isTooLarge(output, TDEA_MAX_BITS_REQUEST / 8)) { throw new IllegalArgumentException("Number of bits per request limited to " + TDEA_MAX_BITS_REQUEST); } } else { if (_reseedCounter > AES_RESEED_MAX) { return -1; } if (Utils.isTooLarge(output, AES_MAX_BITS_REQUEST / 8)) { throw new IllegalArgumentException("Number of bits per request limited to " + AES_MAX_BITS_REQUEST); } } if (predictionResistant) { CTR_DRBG_Reseed_algorithm(additionalInput); additionalInput = null; } if (additionalInput != null) { additionalInput = Block_Cipher_df(additionalInput, _seedLength); CTR_DRBG_Update(additionalInput, _Key, _V); } else { additionalInput = new byte[_seedLength]; } byte[] out = new byte[_V.length]; _engine.init(true, new KeyParameter(expandKey(_Key))); for (int i = 0; i <= output.length / out.length; i++) { int bytesToCopy = ((output.length - i * out.length) > out.length) ? out.length : (output.length - i * _V.length); if (bytesToCopy != 0) { addOneTo(_V); _engine.processBlock(_V, 0, out, 0); System.arraycopy(out, 0, output, i * out.length, bytesToCopy); } } CTR_DRBG_Update(additionalInput, _Key, _V); _reseedCounter++; return output.length * 8; } /** * Reseed the DRBG. * * @param additionalInput additional input to be added to the DRBG in this step. */ public void reseed(byte[] additionalInput) { CTR_DRBG_Reseed_algorithm(additionalInput); } private boolean isTDEA(BlockCipher cipher) { return cipher.getAlgorithmName().equals("DESede") || cipher.getAlgorithmName().equals("TDEA"); } private int getMaxSecurityStrength(BlockCipher cipher, int keySizeInBits) { if (isTDEA(cipher) && keySizeInBits == 168) { return 112; } if (cipher.getAlgorithmName().equals("AES")) { return keySizeInBits; } return -1; } byte[] expandKey(byte[] key) { if (_isTDEA) { // expand key to 192 bits. byte[] tmp = new byte[24]; padKey(key, 0, tmp, 0); padKey(key, 7, tmp, 8); padKey(key, 14, tmp, 16); return tmp; } else { return key; } } /** * Pad out a key for TDEA, setting odd parity for each byte. * * @param keyMaster * @param keyOff * @param tmp * @param tmpOff */ private void padKey(byte[] keyMaster, int keyOff, byte[] tmp, int tmpOff) { tmp[tmpOff + 0] = (byte)(keyMaster[keyOff + 0] & 0xfe); tmp[tmpOff + 1] = (byte)((keyMaster[keyOff + 0] << 7) | ((keyMaster[keyOff + 1] & 0xfc) >>> 1)); tmp[tmpOff + 2] = (byte)((keyMaster[keyOff + 1] << 6) | ((keyMaster[keyOff + 2] & 0xf8) >>> 2)); tmp[tmpOff + 3] = (byte)((keyMaster[keyOff + 2] << 5) | ((keyMaster[keyOff + 3] & 0xf0) >>> 3)); tmp[tmpOff + 4] = (byte)((keyMaster[keyOff + 3] << 4) | ((keyMaster[keyOff + 4] & 0xe0) >>> 4)); tmp[tmpOff + 5] = (byte)((keyMaster[keyOff + 4] << 3) | ((keyMaster[keyOff + 5] & 0xc0) >>> 5)); tmp[tmpOff + 6] = (byte)((keyMaster[keyOff + 5] << 2) | ((keyMaster[keyOff + 6] & 0x80) >>> 6)); tmp[tmpOff + 7] = (byte)(keyMaster[keyOff + 6] << 1); for (int i = tmpOff; i <= tmpOff + 7; i++) { int b = tmp[i]; tmp[i] = (byte)((b & 0xfe) | ((((b >> 1) ^ (b >> 2) ^ (b >> 3) ^ (b >> 4) ^ (b >> 5) ^ (b >> 6) ^ (b >> 7)) ^ 0x01) & 0x01)); } } }




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