diff options
Diffstat (limited to 'gnu/javax/crypto/cipher/TripleDES.java')
| -rw-r--r-- | gnu/javax/crypto/cipher/TripleDES.java | 83 |
1 files changed, 33 insertions, 50 deletions
diff --git a/gnu/javax/crypto/cipher/TripleDES.java b/gnu/javax/crypto/cipher/TripleDES.java index ed50d311c..7aeb4ea96 100644 --- a/gnu/javax/crypto/cipher/TripleDES.java +++ b/gnu/javax/crypto/cipher/TripleDES.java @@ -45,37 +45,34 @@ import java.util.Iterator; import java.security.InvalidKeyException; /** - * Triple-DES, 3DES, or DESede is a <i>combined cipher</i> that uses - * three iterations of the Data Encryption Standard cipher to improve - * the security (at the cost of speed) of plain DES. - * - * <p>Triple-DES runs the DES algorithm three times with three - * independent 56 bit keys. To encrypt:</p> - * - * <blockquote><i>C<sub>i</sub> = - * E<sub>k3</sub> ( E<sub>k2</sub><sup>-1</sup> ( E<sub>k1</sub> ( P<sub>i</sub> )))</i></blockquote> - * - * <p>And to decrypt:</p> - * - * <blockquote><i>P<sub>i</sub> = - * E<sub>k1</sub><sup>-1</sup> ( E<sub>k2</sub> ( E<sub>k3</sub><sup>-1</sup> ( C<sub>i</sub> )))</i></blockquote> - * - * <p>(The "ede" comes from the encryption operation, which runs - * Encrypt-Decrypt-Encrypt)</p> - * - * <p>References:</p> + * Triple-DES, 3DES, or DESede is a <i>combined cipher</i> that uses three + * iterations of the Data Encryption Standard cipher to improve the security (at + * the cost of speed) of plain DES. + * <p> + * Triple-DES runs the DES algorithm three times with three independent 56 bit + * keys. To encrypt: + * <blockquote><i>C<sub>i</sub> = E<sub>k3</sub> ( E<sub>k2</sub><sup>-1</sup> ( + * E<sub>k1</sub> ( P<sub>i</sub> )))</i> + * </blockquote> + * <p> + * And to decrypt: + * <blockquote><i>P<sub>i</sub> = E<sub>k1</sub><sup>-1</sup> ( + * E<sub>k2</sub> ( E<sub>k3</sub><sup>-1</sup> ( C<sub>i</sub> )))</i> + * </blockquote> + * <p> + * (The "ede" comes from the encryption operation, which runs + * Encrypt-Decrypt-Encrypt) + * <p> + * References: * <ol> - * <li>Bruce Schneier, <i>Applied Cryptography: Protocols, Algorithms, - * and Source Code in C, Second Edition</i>. (1996 John Wiley and Sons) - * ISBN 0-471-11709-9. Page 294--295.</li> + * <li>Bruce Schneier, <i>Applied Cryptography: Protocols, Algorithms, and + * Source Code in C, Second Edition</i>. (1996 John Wiley and Sons) ISBN + * 0-471-11709-9. Page 294--295.</li> * </ol> */ -public class TripleDES extends BaseCipher +public class TripleDES + extends BaseCipher { - - // Constants and variables. - // ----------------------------------------------------------------------- - /** Triple-DES only operates on 64 bit blocks. */ public static final int BLOCK_SIZE = 8; @@ -85,9 +82,6 @@ public class TripleDES extends BaseCipher /** The underlying DES instance. */ private DES des; - // Constructors. - // ----------------------------------------------------------------------- - /** * Default 0-arguments constructor. */ @@ -97,13 +91,10 @@ public class TripleDES extends BaseCipher des = new DES(); } - // Class methods. - // ----------------------------------------------------------------------- - /** * Transform a key so it will be parity adjusted. - * - * @param kb The key bytes to adjust. + * + * @param kb The key bytes to adjust. * @param offset The starting offset into the key bytes. * @see DES#adjustParity(byte[],int) */ @@ -116,8 +107,8 @@ public class TripleDES extends BaseCipher /** * Tests if a byte array has already been parity adjusted. - * - * @param kb The key bytes to test. + * + * @param kb The key bytes to test. * @param offset The starting offset into the key bytes. * @return <code>true</code> if the bytes in <i>kb</i> starting at * <i>offset</i> are parity adjusted. @@ -131,9 +122,6 @@ public class TripleDES extends BaseCipher && DES.isParityAdjusted(kb, offset + 16); } - // Methods implementing BaseCipher. - // ----------------------------------------------------------------------- - public Object clone() { return new TripleDES(); @@ -153,20 +141,18 @@ public class TripleDES extends BaseCipher { if (kb.length != KEY_SIZE) throw new InvalidKeyException("TripleDES key must be 24 bytes"); - - if (!isParityAdjusted(kb, 0)) + if (! isParityAdjusted(kb, 0)) adjustParity(kb, 0); - - byte[] k1 = new byte[DES.KEY_SIZE], k2 = new byte[DES.KEY_SIZE], k3 = new byte[DES.KEY_SIZE]; + byte[] k1 = new byte[DES.KEY_SIZE]; + byte[] k2 = new byte[DES.KEY_SIZE]; + byte[] k3 = new byte[DES.KEY_SIZE]; System.arraycopy(kb, 0, k1, 0, DES.KEY_SIZE); System.arraycopy(kb, DES.KEY_SIZE, k2, 0, DES.KEY_SIZE); System.arraycopy(kb, 2 * DES.KEY_SIZE, k3, 0, DES.KEY_SIZE); Context ctx = new Context(); - ctx.k1 = (DES.Context) des.makeKey(k1, bs); ctx.k2 = (DES.Context) des.makeKey(k2, bs); ctx.k3 = (DES.Context) des.makeKey(k3, bs); - return ctx; } @@ -186,11 +172,8 @@ public class TripleDES extends BaseCipher des.decrypt(temp, 0, out, o, ((Context) K).k1, bs); } - // Inner classes. - // ----------------------------------------------------------------------- - private final class Context { DES.Context k1, k2, k3; } -}
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