diff options
Diffstat (limited to 'core/src/main/java/org/spongycastle/crypto/prng/drbg/DualECSP800DRBG.java')
| -rw-r--r-- | core/src/main/java/org/spongycastle/crypto/prng/drbg/DualECSP800DRBG.java | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/prng/drbg/DualECSP800DRBG.java b/core/src/main/java/org/spongycastle/crypto/prng/drbg/DualECSP800DRBG.java new file mode 100644 index 00000000..239ffe57 --- /dev/null +++ b/core/src/main/java/org/spongycastle/crypto/prng/drbg/DualECSP800DRBG.java @@ -0,0 +1,320 @@ +package org.spongycastle.crypto.prng.drbg; + +import java.math.BigInteger; + +import org.spongycastle.asn1.nist.NISTNamedCurves; +import org.spongycastle.crypto.Digest; +import org.spongycastle.crypto.prng.EntropySource; +import org.spongycastle.math.ec.ECCurve; +import org.spongycastle.math.ec.ECMultiplier; +import org.spongycastle.math.ec.ECPoint; +import org.spongycastle.math.ec.FixedPointCombMultiplier; +import org.spongycastle.util.Arrays; +import org.spongycastle.util.BigIntegers; + +/** + * A SP800-90A Dual EC DRBG. + */ +public class DualECSP800DRBG + implements SP80090DRBG +{ + /* + * Default P, Q values for each curve + */ + private static final BigInteger p256_Px = new BigInteger("6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296", 16); + private static final BigInteger p256_Py = new BigInteger("4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5", 16); + private static final BigInteger p256_Qx = new BigInteger("c97445f45cdef9f0d3e05e1e585fc297235b82b5be8ff3efca67c59852018192", 16); + private static final BigInteger p256_Qy = new BigInteger("b28ef557ba31dfcbdd21ac46e2a91e3c304f44cb87058ada2cb815151e610046", 16); + + private static final BigInteger p384_Px = new BigInteger("aa87ca22be8b05378eb1c71ef320ad746e1d3b628ba79b9859f741e082542a385502f25dbf55296c3a545e3872760ab7", 16); + private static final BigInteger p384_Py = new BigInteger("3617de4a96262c6f5d9e98bf9292dc29f8f41dbd289a147ce9da3113b5f0b8c00a60b1ce1d7e819d7a431d7c90ea0e5f", 16); + private static final BigInteger p384_Qx = new BigInteger("8e722de3125bddb05580164bfe20b8b432216a62926c57502ceede31c47816edd1e89769124179d0b695106428815065", 16); + private static final BigInteger p384_Qy = new BigInteger("023b1660dd701d0839fd45eec36f9ee7b32e13b315dc02610aa1b636e346df671f790f84c5e09b05674dbb7e45c803dd", 16); + + private static final BigInteger p521_Px = new BigInteger("c6858e06b70404e9cd9e3ecb662395b4429c648139053fb521f828af606b4d3dbaa14b5e77efe75928fe1dc127a2ffa8de3348b3c1856a429bf97e7e31c2e5bd66", 16); + private static final BigInteger p521_Py = new BigInteger("11839296a789a3bc0045c8a5fb42c7d1bd998f54449579b446817afbd17273e662c97ee72995ef42640c550b9013fad0761353c7086a272c24088be94769fd16650", 16); + private static final BigInteger p521_Qx = new BigInteger("1b9fa3e518d683c6b65763694ac8efbaec6fab44f2276171a42726507dd08add4c3b3f4c1ebc5b1222ddba077f722943b24c3edfa0f85fe24d0c8c01591f0be6f63", 16); + private static final BigInteger p521_Qy = new BigInteger("1f3bdba585295d9a1110d1df1f9430ef8442c5018976ff3437ef91b81dc0b8132c8d5c39c32d0e004a3092b7d327c0e7a4d26d2c7b69b58f9066652911e457779de", 16); + + private static final DualECPoints[] nistPoints; + + static + { + nistPoints = new DualECPoints[3]; + + ECCurve.Fp curve = (ECCurve.Fp)NISTNamedCurves.getByName("P-256").getCurve(); + + nistPoints[0] = new DualECPoints(128, curve.createPoint(p256_Px, p256_Py), curve.createPoint(p256_Qx, p256_Qy), 1); + + curve = (ECCurve.Fp)NISTNamedCurves.getByName("P-384").getCurve(); + + nistPoints[1] = new DualECPoints(192, curve.createPoint(p384_Px, p384_Py), curve.createPoint(p384_Qx, p384_Qy), 1); + + curve = (ECCurve.Fp)NISTNamedCurves.getByName("P-521").getCurve(); + + nistPoints[2] = new DualECPoints(256, curve.createPoint(p521_Px, p521_Py), curve.createPoint(p521_Qx, p521_Qy), 1); + } + + + private static final long RESEED_MAX = 1L << (32 - 1); + private static final int MAX_ADDITIONAL_INPUT = 1 << (13 - 1); + private static final int MAX_ENTROPY_LENGTH = 1 << (13 - 1); + private static final int MAX_PERSONALIZATION_STRING = 1 << (13 -1); + + private Digest _digest; + private long _reseedCounter; + private EntropySource _entropySource; + private int _securityStrength; + private int _seedlen; + private int _outlen; + private ECCurve.Fp _curve; + private ECPoint _P; + private ECPoint _Q; + private byte[] _s; + private int _sLength; + private ECMultiplier _fixedPointMultiplier = new FixedPointCombMultiplier(); + + /** + * Construct a SP800-90A Dual EC DRBG. + * <p> + * Minimum entropy requirement is the security strength requested. + * </p> + * @param digest source digest to use with the 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 DualECSP800DRBG(Digest digest, int securityStrength, EntropySource entropySource, byte[] personalizationString, byte[] nonce) + { + this(nistPoints, digest, securityStrength, entropySource, personalizationString, nonce); + } + + /** + * Construct a SP800-90A Dual EC DRBG. + * <p> + * Minimum entropy requirement is the security strength requested. + * </p> + * @param pointSet an array of points to choose from, in order of increasing security strength + * @param digest source digest to use with the 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 DualECSP800DRBG(DualECPoints[] pointSet, Digest digest, int securityStrength, EntropySource entropySource, byte[] personalizationString, byte[] nonce) + { + _digest = digest; + _entropySource = entropySource; + _securityStrength = securityStrength; + + if (Utils.isTooLarge(personalizationString, MAX_PERSONALIZATION_STRING / 8)) + { + throw new IllegalArgumentException("Personalization string too large"); + } + + if (entropySource.entropySize() < securityStrength || entropySource.entropySize() > MAX_ENTROPY_LENGTH) + { + throw new IllegalArgumentException("EntropySource must provide between " + securityStrength + " and " + MAX_ENTROPY_LENGTH + " bits"); + } + + byte[] entropy = entropySource.getEntropy(); + byte[] seedMaterial = Arrays.concatenate(entropy, nonce, personalizationString); + + for (int i = 0; i != pointSet.length; i++) + { + if (securityStrength <= pointSet[i].getSecurityStrength()) + { + if (Utils.getMaxSecurityStrength(digest) < pointSet[i].getSecurityStrength()) + { + throw new IllegalArgumentException("Requested security strength is not supported by digest"); + } + _seedlen = pointSet[i].getSeedLen(); + _outlen = pointSet[i].getMaxOutlen() / 8; + _P = pointSet[i].getP(); + _Q = pointSet[i].getQ(); + break; + } + } + + if (_P == null) + { + throw new IllegalArgumentException("security strength cannot be greater than 256 bits"); + } + + _s = Utils.hash_df(_digest, seedMaterial, _seedlen); + _sLength = _s.length; + + _reseedCounter = 0; + } + + /** + * 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 _outlen * 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) + { + int numberOfBits = output.length*8; + int m = output.length / _outlen; + + if (Utils.isTooLarge(additionalInput, MAX_ADDITIONAL_INPUT / 8)) + { + throw new IllegalArgumentException("Additional input too large"); + } + + if (_reseedCounter + m > RESEED_MAX) + { + return -1; + } + + if (predictionResistant) + { + reseed(additionalInput); + additionalInput = null; + } + + BigInteger s; + + if (additionalInput != null) + { + // Note: we ignore the use of pad8 on the additional input as we mandate byte arrays for it. + additionalInput = Utils.hash_df(_digest, additionalInput, _seedlen); + s = new BigInteger(1, xor(_s, additionalInput)); + } + else + { + s = new BigInteger(1, _s); + } + + // make sure we start with a clean output array. + Arrays.fill(output, (byte)0); + + int outOffset = 0; + + for (int i = 0; i < m; i++) + { + s = getScalarMultipleXCoord(_P, s); + + //System.err.println("S: " + new String(Hex.encode(_s))); + + byte[] r = getScalarMultipleXCoord(_Q, s).toByteArray(); + + if (r.length > _outlen) + { + System.arraycopy(r, r.length - _outlen, output, outOffset, _outlen); + } + else + { + System.arraycopy(r, 0, output, outOffset + (_outlen - r.length), r.length); + } + + //System.err.println("R: " + new String(Hex.encode(r))); + outOffset += _outlen; + + _reseedCounter++; + } + + if (outOffset < output.length) + { + s = getScalarMultipleXCoord(_P, s); + + byte[] r = getScalarMultipleXCoord(_Q, s).toByteArray(); + + int required = output.length - outOffset; + + if (r.length > _outlen) + { + System.arraycopy(r, r.length - _outlen, output, outOffset, required); + } + else + { + System.arraycopy(r, 0, output, outOffset + (_outlen - r.length), required); + } + + _reseedCounter++; + } + + // Need to preserve length of S as unsigned int. + _s = BigIntegers.asUnsignedByteArray(_sLength, getScalarMultipleXCoord(_P, s)); + + return numberOfBits; + } + + /** + * Reseed the DRBG. + * + * @param additionalInput additional input to be added to the DRBG in this step. + */ + public void reseed(byte[] additionalInput) + { + if (Utils.isTooLarge(additionalInput, MAX_ADDITIONAL_INPUT / 8)) + { + throw new IllegalArgumentException("Additional input string too large"); + } + + byte[] entropy = _entropySource.getEntropy(); + byte[] seedMaterial = Arrays.concatenate(pad8(_s, _seedlen), entropy, additionalInput); + + _s = Utils.hash_df(_digest, seedMaterial, _seedlen); + + _reseedCounter = 0; + } + + private byte[] xor(byte[] a, byte[] b) + { + if (b == null) + { + return a; + } + + byte[] rv = new byte[a.length]; + + for (int i = 0; i != rv.length; i++) + { + rv[i] = (byte)(a[i] ^ b[i]); + } + + return rv; + } + + // Note: works in place + private byte[] pad8(byte[] s, int seedlen) + { + if (seedlen % 8 == 0) + { + return s; + } + + int shift = 8 - (seedlen % 8); + int carry = 0; + + for (int i = s.length - 1; i >= 0; i--) + { + int b = s[i] & 0xff; + s[i] = (byte)((b << shift) | (carry >> (8 - shift))); + carry = b; + } + + return s; + } + + private BigInteger getScalarMultipleXCoord(ECPoint p, BigInteger s) + { + return _fixedPointMultiplier.multiply(p, s).normalize().getAffineXCoord().toBigInteger(); + } +} |