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Diffstat (limited to 'core/src/main/java/org/bouncycastle/pqc/crypto/mceliece/McEliecePKCSCipher.java')
| -rw-r--r-- | core/src/main/java/org/bouncycastle/pqc/crypto/mceliece/McEliecePKCSCipher.java | 224 |
1 files changed, 0 insertions, 224 deletions
diff --git a/core/src/main/java/org/bouncycastle/pqc/crypto/mceliece/McEliecePKCSCipher.java b/core/src/main/java/org/bouncycastle/pqc/crypto/mceliece/McEliecePKCSCipher.java deleted file mode 100644 index 7a6be1be..00000000 --- a/core/src/main/java/org/bouncycastle/pqc/crypto/mceliece/McEliecePKCSCipher.java +++ /dev/null @@ -1,224 +0,0 @@ -package org.bouncycastle.pqc.crypto.mceliece; - -import java.security.SecureRandom; - -import org.bouncycastle.crypto.CipherParameters; -import org.bouncycastle.crypto.params.ParametersWithRandom; -import org.bouncycastle.pqc.crypto.MessageEncryptor; -import org.bouncycastle.pqc.math.linearalgebra.GF2Matrix; -import org.bouncycastle.pqc.math.linearalgebra.GF2Vector; -import org.bouncycastle.pqc.math.linearalgebra.GF2mField; -import org.bouncycastle.pqc.math.linearalgebra.GoppaCode; -import org.bouncycastle.pqc.math.linearalgebra.Permutation; -import org.bouncycastle.pqc.math.linearalgebra.PolynomialGF2mSmallM; -import org.bouncycastle.pqc.math.linearalgebra.Vector; - -/** - * This class implements the McEliece Public Key cryptosystem (McEliecePKCS). It - * was first described in R.J. McEliece, "A public key cryptosystem based on - * algebraic coding theory", DSN progress report, 42-44:114-116, 1978. The - * McEliecePKCS is the first cryptosystem which is based on error correcting - * codes. The trapdoor for the McEliece cryptosystem using Goppa codes is the - * knowledge of the Goppa polynomial used to generate the code. - */ -public class McEliecePKCSCipher - implements MessageEncryptor -{ - - /** - * The OID of the algorithm. - */ - public static final String OID = "1.3.6.1.4.1.8301.3.1.3.4.1"; - - - // the source of randomness - private SecureRandom sr; - - // the McEliece main parameters - private int n, k, t; - - // The maximum number of bytes the cipher can decrypt - public int maxPlainTextSize; - - // The maximum number of bytes the cipher can encrypt - public int cipherTextSize; - - McElieceKeyParameters key; - - - public void init(boolean forSigning, - CipherParameters param) - { - - if (forSigning) - { - if (param instanceof ParametersWithRandom) - { - ParametersWithRandom rParam = (ParametersWithRandom)param; - - this.sr = rParam.getRandom(); - this.key = (McEliecePublicKeyParameters)rParam.getParameters(); - this.initCipherEncrypt((McEliecePublicKeyParameters)key); - - } - else - { - this.sr = new SecureRandom(); - this.key = (McEliecePublicKeyParameters)param; - this.initCipherEncrypt((McEliecePublicKeyParameters)key); - } - } - else - { - this.key = (McEliecePrivateKeyParameters)param; - this.initCipherDecrypt((McEliecePrivateKeyParameters)key); - } - - } - - - /** - * Return the key size of the given key object. - * - * @param key the McElieceKeyParameters object - * @return the keysize of the given key object - */ - - public int getKeySize(McElieceKeyParameters key) - { - - if (key instanceof McEliecePublicKeyParameters) - { - return ((McEliecePublicKeyParameters)key).getN(); - - } - if (key instanceof McEliecePrivateKeyParameters) - { - return ((McEliecePrivateKeyParameters)key).getN(); - } - throw new IllegalArgumentException("unsupported type"); - - } - - - public void initCipherEncrypt(McEliecePublicKeyParameters pubKey) - { - this.sr = sr != null ? sr : new SecureRandom(); - n = pubKey.getN(); - k = pubKey.getK(); - t = pubKey.getT(); - cipherTextSize = n >> 3; - maxPlainTextSize = (k >> 3); - } - - - public void initCipherDecrypt(McEliecePrivateKeyParameters privKey) - { - n = privKey.getN(); - k = privKey.getK(); - - maxPlainTextSize = (k >> 3); - cipherTextSize = n >> 3; - } - - /** - * Encrypt a plain text. - * - * @param input the plain text - * @return the cipher text - */ - public byte[] messageEncrypt(byte[] input) - { - GF2Vector m = computeMessageRepresentative(input); - GF2Vector z = new GF2Vector(n, t, sr); - - GF2Matrix g = ((McEliecePublicKeyParameters)key).getG(); - Vector mG = g.leftMultiply(m); - GF2Vector mGZ = (GF2Vector)mG.add(z); - - return mGZ.getEncoded(); - } - - private GF2Vector computeMessageRepresentative(byte[] input) - { - byte[] data = new byte[maxPlainTextSize + ((k & 0x07) != 0 ? 1 : 0)]; - System.arraycopy(input, 0, data, 0, input.length); - data[input.length] = 0x01; - return GF2Vector.OS2VP(k, data); - } - - /** - * Decrypt a cipher text. - * - * @param input the cipher text - * @return the plain text - * @throws Exception if the cipher text is invalid. - */ - public byte[] messageDecrypt(byte[] input) - throws Exception - { - GF2Vector vec = GF2Vector.OS2VP(n, input); - McEliecePrivateKeyParameters privKey = (McEliecePrivateKeyParameters)key; - GF2mField field = privKey.getField(); - PolynomialGF2mSmallM gp = privKey.getGoppaPoly(); - GF2Matrix sInv = privKey.getSInv(); - Permutation p1 = privKey.getP1(); - Permutation p2 = privKey.getP2(); - GF2Matrix h = privKey.getH(); - PolynomialGF2mSmallM[] qInv = privKey.getQInv(); - - // compute permutation P = P1 * P2 - Permutation p = p1.rightMultiply(p2); - - // compute P^-1 - Permutation pInv = p.computeInverse(); - - // compute c P^-1 - GF2Vector cPInv = (GF2Vector)vec.multiply(pInv); - - // compute syndrome of c P^-1 - GF2Vector syndrome = (GF2Vector)h.rightMultiply(cPInv); - - // decode syndrome - GF2Vector z = GoppaCode.syndromeDecode(syndrome, field, gp, qInv); - GF2Vector mSG = (GF2Vector)cPInv.add(z); - - // multiply codeword with P1 and error vector with P - mSG = (GF2Vector)mSG.multiply(p1); - z = (GF2Vector)z.multiply(p); - - // extract mS (last k columns of mSG) - GF2Vector mS = mSG.extractRightVector(k); - - // compute plaintext vector - GF2Vector mVec = (GF2Vector)sInv.leftMultiply(mS); - - // compute and return plaintext - return computeMessage(mVec); - } - - private byte[] computeMessage(GF2Vector mr) - throws Exception - { - byte[] mrBytes = mr.getEncoded(); - // find first non-zero byte - int index; - for (index = mrBytes.length - 1; index >= 0 && mrBytes[index] == 0; index--) - { - ; - } - - // check if padding byte is valid - if (mrBytes[index] != 0x01) - { - throw new Exception("Bad Padding: invalid ciphertext"); - } - - // extract and return message - byte[] mBytes = new byte[index]; - System.arraycopy(mrBytes, 0, mBytes, 0, index); - return mBytes; - } - - -} |