diff options
Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/mode/CTR.java')
| -rw-r--r-- | libjava/classpath/gnu/javax/crypto/mode/CTR.java | 127 |
1 files changed, 37 insertions, 90 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/mode/CTR.java b/libjava/classpath/gnu/javax/crypto/mode/CTR.java index 49f4b9f3c2a..0c856b483ee 100644 --- a/libjava/classpath/gnu/javax/crypto/mode/CTR.java +++ b/libjava/classpath/gnu/javax/crypto/mode/CTR.java @@ -40,59 +40,50 @@ package gnu.javax.crypto.mode; import gnu.java.security.Registry; import gnu.java.security.util.Sequence; - import gnu.javax.crypto.cipher.IBlockCipher; -import java.math.BigInteger; import java.util.Arrays; import java.util.Iterator; /** - * <p>The implementation of the Counter Mode.</p> - * - * <p>The algorithm steps are formally described as follows:</p> - * + * The implementation of the Counter Mode. + * <p> + * The algorithm steps are formally described as follows: + * * <pre> - * CTR Encryption: O[j] = E(K)(T[j]); for j = 1, 2...n; - * C[j] = P[j] ^ O[j]; for j = 1, 2...n. - * CTR Decryption: O[j] = E(K)(T[j]); for j = 1, 2...n; - * P[j] = C[j] ^ O[j]; for j = 1, 2...n. + * CTR Encryption: O[j] = E(K)(T[j]); for j = 1, 2...n; + * C[j] = P[j] ˆ O[j]; for j = 1, 2...n. + * CTR Decryption: O[j] = E(K)(T[j]); for j = 1, 2...n; + * P[j] = C[j] ˆ O[j]; for j = 1, 2...n. * </pre> - * - * <p>where <code>P</code> is the plaintext, <code>C</code> is the ciphertext, + * + * <p> + * where <code>P</code> is the plaintext, <code>C</code> is the ciphertext, * <code>E(K)</code> is the underlying block cipher encryption function - * parametrised with the session key <code>K</code>, and <code>T</code> is the - * <i>Counter</i>.</p> - * - * <p>This implementation, uses a standard incrementing function with a step of - * 1, and an initial value similar to that described in the NIST document.</p> - * - * <p>References:</p> - * + * parametrised with the session key <code>K</code>, and <code>T</code> is + * the <i>Counter</i>. + * <p> + * This implementation, uses a standard incrementing function with a step of 1, + * and an initial value similar to that described in the NIST document. + * <p> + * References: * <ol> - * <li><a href="http://csrc.nist.gov/encryption/modes/Recommendation/Modes01.pdf"> - * Recommendation for Block Cipher Modes of Operation Methods and Techniques</a>, - * Morris Dworkin.</li> + * <li><a + * href="http://csrc.nist.gov/encryption/modes/Recommendation/Modes01.pdf"> + * Recommendation for Block Cipher Modes of Operation Methods and Techniques</a>, + * Morris Dworkin.</li> * </ol> */ -public class CTR extends BaseMode implements Cloneable +public class CTR + extends BaseMode + implements Cloneable { - - // Constants and variables - // ------------------------------------------------------------------------- - - /** The current counter. */ - // private BigInteger T; private int off; - private byte[] counter, enc; - // Constructor(s) - // ------------------------------------------------------------------------- - /** - * <p>Trivial package-private constructor for use by the Factory class.</p> - * + * Trivial package-private constructor for use by the Factory class. + * * @param underlyingCipher the underlying cipher implementation. * @param cipherBlockSize the underlying cipher block size to use. */ @@ -102,8 +93,8 @@ public class CTR extends BaseMode implements Cloneable } /** - * <p>Private constructor for cloning purposes.</p> - * + * Private constructor for cloning purposes. + * * @param that the instance to clone. */ private CTR(CTR that) @@ -111,61 +102,31 @@ public class CTR extends BaseMode implements Cloneable this((IBlockCipher) that.cipher.clone(), that.cipherBlockSize); } - // Class methods - // ------------------------------------------------------------------------- - - // Cloneable interface implementation - // ------------------------------------------------------------------------- - public Object clone() { return new CTR(this); } - // Implementation of abstract methods in BaseMode - // ------------------------------------------------------------------------- - public void setup() { if (modeBlockSize > cipherBlockSize) - { - throw new IllegalArgumentException( - "mode size exceeds cipher block size"); - } + throw new IllegalArgumentException("mode size exceeds cipher block size"); off = 0; counter = new byte[cipherBlockSize]; int i = cipherBlockSize - 1; int j = iv.length - 1; while (i >= 0 && j >= 0) - { - counter[i--] = iv[j--]; - } + counter[i--] = iv[j--]; enc = new byte[cipherBlockSize]; cipher.encryptBlock(counter, 0, enc, 0); - // if (modeBlockSize != cipherBlockSize) { - // throw new IllegalArgumentException(); - // } - - // byte[] tBytes = new byte[modeBlockSize+1]; - // tBytes[0] = (byte) 0x80; - // for (int i = 0; i < modeBlockSize; i++) { - // tBytes[i+1] = (byte)(256 - modeBlockSize + i); - // } - - // T = new BigInteger(1, tBytes); } public void teardown() { if (counter != null) - { - Arrays.fill(counter, (byte) 0); - } + Arrays.fill(counter, (byte) 0); if (enc != null) - { - Arrays.fill(enc, (byte) 0); - } - // T = null; + Arrays.fill(enc, (byte) 0); } public void encryptBlock(byte[] in, int i, byte[] out, int o) @@ -183,21 +144,11 @@ public class CTR extends BaseMode implements Cloneable return new Sequence(1, cipherBlockSize).iterator(); } - // own methods - // ------------------------------------------------------------------------- - private void ctr(byte[] in, int inOffset, byte[] out, int outOffset) { - // T = T.add(BigInteger.ONE); - // byte[] O = T.toByteArray(); - // int ndx = O.length - modeBlockSize; - // cipher.encryptBlock(O, ndx, O, ndx); - // for (int i = 0; i < modeBlockSize; i++) { - // out[outOffset++] = (byte)(in[inOffset++] ^ O[ndx++]); - // } for (int i = 0; i < modeBlockSize; i++) { - out[outOffset++] = (byte) (in[inOffset++] ^ enc[off++]); + out[outOffset++] = (byte)(in[inOffset++] ^ enc[off++]); if (off == cipherBlockSize) { int j; @@ -205,17 +156,13 @@ public class CTR extends BaseMode implements Cloneable { counter[j]++; if ((counter[j] & 0xFF) != 0) - { - break; - } + break; } if (j == 0) - { - counter[cipherBlockSize - 1]++; - } + counter[cipherBlockSize - 1]++; off = 0; cipher.encryptBlock(counter, 0, enc, 0); } } } -}
\ No newline at end of file +} |
