diff options
Diffstat (limited to 'core/src/main/java/org/bouncycastle/crypto/encodings/ISO9796d1Encoding.java')
| -rw-r--r-- | core/src/main/java/org/bouncycastle/crypto/encodings/ISO9796d1Encoding.java | 287 |
1 files changed, 0 insertions, 287 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/encodings/ISO9796d1Encoding.java b/core/src/main/java/org/bouncycastle/crypto/encodings/ISO9796d1Encoding.java deleted file mode 100644 index ec91e1ac..00000000 --- a/core/src/main/java/org/bouncycastle/crypto/encodings/ISO9796d1Encoding.java +++ /dev/null @@ -1,287 +0,0 @@ -package org.bouncycastle.crypto.encodings; - -import java.math.BigInteger; - -import org.bouncycastle.crypto.AsymmetricBlockCipher; -import org.bouncycastle.crypto.CipherParameters; -import org.bouncycastle.crypto.InvalidCipherTextException; -import org.bouncycastle.crypto.params.ParametersWithRandom; -import org.bouncycastle.crypto.params.RSAKeyParameters; - -/** - * ISO 9796-1 padding. Note in the light of recent results you should - * only use this with RSA (rather than the "simpler" Rabin keys) and you - * should never use it with anything other than a hash (ie. even if the - * message is small don't sign the message, sign it's hash) or some "random" - * value. See your favorite search engine for details. - */ -public class ISO9796d1Encoding - implements AsymmetricBlockCipher -{ - private static final BigInteger SIXTEEN = BigInteger.valueOf(16L); - private static final BigInteger SIX = BigInteger.valueOf(6L); - - private static byte[] shadows = { 0xe, 0x3, 0x5, 0x8, 0x9, 0x4, 0x2, 0xf, - 0x0, 0xd, 0xb, 0x6, 0x7, 0xa, 0xc, 0x1 }; - private static byte[] inverse = { 0x8, 0xf, 0x6, 0x1, 0x5, 0x2, 0xb, 0xc, - 0x3, 0x4, 0xd, 0xa, 0xe, 0x9, 0x0, 0x7 }; - - private AsymmetricBlockCipher engine; - private boolean forEncryption; - private int bitSize; - private int padBits = 0; - private BigInteger modulus; - - public ISO9796d1Encoding( - AsymmetricBlockCipher cipher) - { - this.engine = cipher; - } - - public AsymmetricBlockCipher getUnderlyingCipher() - { - return engine; - } - - public void init( - boolean forEncryption, - CipherParameters param) - { - RSAKeyParameters kParam = null; - - if (param instanceof ParametersWithRandom) - { - ParametersWithRandom rParam = (ParametersWithRandom)param; - - kParam = (RSAKeyParameters)rParam.getParameters(); - } - else - { - kParam = (RSAKeyParameters)param; - } - - engine.init(forEncryption, param); - - modulus = kParam.getModulus(); - bitSize = modulus.bitLength(); - - this.forEncryption = forEncryption; - } - - /** - * return the input block size. The largest message we can process - * is (key_size_in_bits + 3)/16, which in our world comes to - * key_size_in_bytes / 2. - */ - public int getInputBlockSize() - { - int baseBlockSize = engine.getInputBlockSize(); - - if (forEncryption) - { - return (baseBlockSize + 1) / 2; - } - else - { - return baseBlockSize; - } - } - - /** - * return the maximum possible size for the output. - */ - public int getOutputBlockSize() - { - int baseBlockSize = engine.getOutputBlockSize(); - - if (forEncryption) - { - return baseBlockSize; - } - else - { - return (baseBlockSize + 1) / 2; - } - } - - /** - * set the number of bits in the next message to be treated as - * pad bits. - */ - public void setPadBits( - int padBits) - { - if (padBits > 7) - { - throw new IllegalArgumentException("padBits > 7"); - } - - this.padBits = padBits; - } - - /** - * retrieve the number of pad bits in the last decoded message. - */ - public int getPadBits() - { - return padBits; - } - - public byte[] processBlock( - byte[] in, - int inOff, - int inLen) - throws InvalidCipherTextException - { - if (forEncryption) - { - return encodeBlock(in, inOff, inLen); - } - else - { - return decodeBlock(in, inOff, inLen); - } - } - - private byte[] encodeBlock( - byte[] in, - int inOff, - int inLen) - throws InvalidCipherTextException - { - byte[] block = new byte[(bitSize + 7) / 8]; - int r = padBits + 1; - int z = inLen; - int t = (bitSize + 13) / 16; - - for (int i = 0; i < t; i += z) - { - if (i > t - z) - { - System.arraycopy(in, inOff + inLen - (t - i), - block, block.length - t, t - i); - } - else - { - System.arraycopy(in, inOff, block, block.length - (i + z), z); - } - } - - for (int i = block.length - 2 * t; i != block.length; i += 2) - { - byte val = block[block.length - t + i / 2]; - - block[i] = (byte)((shadows[(val & 0xff) >>> 4] << 4) - | shadows[val & 0x0f]); - block[i + 1] = val; - } - - block[block.length - 2 * z] ^= r; - block[block.length - 1] = (byte)((block[block.length - 1] << 4) | 0x06); - - int maxBit = (8 - (bitSize - 1) % 8); - int offSet = 0; - - if (maxBit != 8) - { - block[0] &= 0xff >>> maxBit; - block[0] |= 0x80 >>> maxBit; - } - else - { - block[0] = 0x00; - block[1] |= 0x80; - offSet = 1; - } - - return engine.processBlock(block, offSet, block.length - offSet); - } - - /** - * @exception InvalidCipherTextException if the decrypted block is not a valid ISO 9796 bit string - */ - private byte[] decodeBlock( - byte[] in, - int inOff, - int inLen) - throws InvalidCipherTextException - { - byte[] block = engine.processBlock(in, inOff, inLen); - int r = 1; - int t = (bitSize + 13) / 16; - - BigInteger iS = new BigInteger(1, block); - BigInteger iR; - if (iS.mod(SIXTEEN).equals(SIX)) - { - iR = iS; - } - else if ((modulus.subtract(iS)).mod(SIXTEEN).equals(SIX)) - { - iR = modulus.subtract(iS); - } - else - { - throw new InvalidCipherTextException("resulting integer iS or (modulus - iS) is not congruent to 6 mod 16"); - } - - block = convertOutputDecryptOnly(iR); - - if ((block[block.length - 1] & 0x0f) != 0x6 ) - { - throw new InvalidCipherTextException("invalid forcing byte in block"); - } - - block[block.length - 1] = (byte)(((block[block.length - 1] & 0xff) >>> 4) | ((inverse[(block[block.length - 2] & 0xff) >> 4]) << 4)); - block[0] = (byte)((shadows[(block[1] & 0xff) >>> 4] << 4) - | shadows[block[1] & 0x0f]); - - boolean boundaryFound = false; - int boundary = 0; - - for (int i = block.length - 1; i >= block.length - 2 * t; i -= 2) - { - int val = ((shadows[(block[i] & 0xff) >>> 4] << 4) - | shadows[block[i] & 0x0f]); - - if (((block[i - 1] ^ val) & 0xff) != 0) - { - if (!boundaryFound) - { - boundaryFound = true; - r = (block[i - 1] ^ val) & 0xff; - boundary = i - 1; - } - else - { - throw new InvalidCipherTextException("invalid tsums in block"); - } - } - } - - block[boundary] = 0; - - byte[] nblock = new byte[(block.length - boundary) / 2]; - - for (int i = 0; i < nblock.length; i++) - { - nblock[i] = block[2 * i + boundary + 1]; - } - - padBits = r - 1; - - return nblock; - } - - private static byte[] convertOutputDecryptOnly(BigInteger result) - { - byte[] output = result.toByteArray(); - if (output[0] == 0) // have ended up with an extra zero byte, copy down. - { - byte[] tmp = new byte[output.length - 1]; - System.arraycopy(output, 1, tmp, 0, tmp.length); - return tmp; - } - return output; - } -} |