package gnu.java.security.sig.rsa;
+import gnu.java.security.Configuration;
import gnu.java.security.hash.HashFactory;
import gnu.java.security.hash.IMessageDigest;
import gnu.java.security.util.Util;
-import java.io.PrintWriter;
import java.util.Arrays;
+import java.util.logging.Logger;
/**
- * <p>An implementation of the EMSA-PSS encoding/decoding scheme.</p>
- *
- * <p>EMSA-PSS coincides with EMSA4 in IEEE P1363a D5 except that EMSA-PSS acts
- * on octet strings and not on bit strings. In particular, the bit lengths of
- * the hash and the salt must be multiples of 8 in EMSA-PSS. Moreover, EMSA4
- * outputs an integer of a desired bit length rather than an octet string.</p>
- *
- * <p>EMSA-PSS is parameterized by the choice of hash function Hash and mask
+ * An implementation of the EMSA-PSS encoding/decoding scheme.
+ * <p>
+ * EMSA-PSS coincides with EMSA4 in IEEE P1363a D5 except that EMSA-PSS acts on
+ * octet strings and not on bit strings. In particular, the bit lengths of the
+ * hash and the salt must be multiples of 8 in EMSA-PSS. Moreover, EMSA4 outputs
+ * an integer of a desired bit length rather than an octet string.
+ * <p>
+ * EMSA-PSS is parameterized by the choice of hash function Hash and mask
* generation function MGF. In this submission, MGF is based on a Hash
* definition that coincides with the corresponding definitions in IEEE Std
* 1363-2000, PKCS #1 v2.0, and the draft ANSI X9.44. In PKCS #1 v2.0 and the
* draft ANSI X9.44, the recommended hash function is SHA-1, while IEEE Std
- * 1363-2000 recommends SHA-1 and RIPEMD-160.</p>
- *
- * <p>References:</p>
+ * 1363-2000 recommends SHA-1 and RIPEMD-160.
+ * <p>
+ * References:
* <ol>
- * <li><a href="http://www.cosic.esat.kuleuven.ac.be/nessie/workshop/submissions/rsa-pss.zip">
- * RSA-PSS Signature Scheme with Appendix, part B.</a><br>
- * Primitive specification and supporting documentation.<br>
- * Jakob Jonsson and Burt Kaliski.</li>
+ * <li><a
+ * href="http://www.cosic.esat.kuleuven.ac.be/nessie/workshop/submissions/rsa-pss.zip">
+ * RSA-PSS Signature Scheme with Appendix, part B.</a><br>
+ * Primitive specification and supporting documentation.<br>
+ * Jakob Jonsson and Burt Kaliski.</li>
* </ol>
*/
-public class EMSA_PSS implements Cloneable
+public class EMSA_PSS
+ implements Cloneable
{
-
- // Debugging methods and variables
- // -------------------------------------------------------------------------
-
- private static final String NAME = "emsa-pss";
-
- private static final boolean DEBUG = false;
-
- private static final int debuglevel = 5;
-
- private static final PrintWriter err = new PrintWriter(System.out, true);
-
- private static void debug(String s)
- {
- err.println(">>> " + NAME + ": " + s);
- }
-
- // Constants and variables
- // -------------------------------------------------------------------------
+ private static final Logger log = Logger.getLogger(EMSA_PSS.class.getName());
/** The underlying hash function to use with this instance. */
private IMessageDigest hash;
/** The output size of the hash function in octets. */
private int hLen;
- // Constructor(s)
- // -------------------------------------------------------------------------
-
/**
- * <p>Trivial private constructor to enforce use through Factory method.</p>
- *
+ * Trivial private constructor to enforce use through Factory method.
+ *
* @param hash the message digest instance to use with this scheme instance.
*/
private EMSA_PSS(IMessageDigest hash)
hLen = hash.hashSize();
}
- // Class methods
- // -------------------------------------------------------------------------
-
/**
- * <p>Returns an instance of this object given a designated name of a hash
- * function.</p>
- *
+ * Returns an instance of this object given a designated name of a hash
+ * function.
+ *
* @param mdName the canonical name of a hash function.
* @return an instance of this object configured for use with the designated
- * options.
+ * options.
*/
public static EMSA_PSS getInstance(String mdName)
{
return new EMSA_PSS(hash);
}
- // Instance methods
- // -------------------------------------------------------------------------
-
- // Cloneable interface implementation --------------------------------------
-
public Object clone()
{
return getInstance(hash.name());
}
- // own methods -------------------------------------------------------------
-
/**
- * <p>The encoding operation EMSA-PSS-Encode computes the hash of a message
+ * The encoding operation EMSA-PSS-Encode computes the hash of a message
* <code>M</code> using a hash function and maps the result to an encoded
* message <code>EM</code> of a specified length using a mask generation
- * function.</p>
- *
+ * function.
+ *
* @param mHash the byte sequence resulting from applying the message digest
- * algorithm Hash to the message <i>M</i>.
+ * algorithm Hash to the message <i>M</i>.
* @param emBits the maximal bit length of the integer OS2IP(EM), at least
- * <code>8.hLen + 8.sLen + 9</code>.
+ * <code>8.hLen + 8.sLen + 9</code>.
* @param salt the salt to use when encoding the output.
* @return the encoded message <code>EM</code>, an octet string of length
- * <code>emLen = CEILING(emBits / 8)</code>.
+ * <code>emLen = CEILING(emBits / 8)</code>.
* @exception IllegalArgumentException if an exception occurs.
- *
*/
public byte[] encode(byte[] mHash, int emBits, byte[] salt)
{
int sLen = salt.length;
-
// 1. If the length of M is greater than the input limitation for the hash
// function (2**61 - 1 octets for SHA-1) then output "message too long"
// and stop.
// 2. Let mHash = Hash(M), an octet string of length hLen.
if (hLen != mHash.length)
- {
- throw new IllegalArgumentException("wrong hash");
- }
+ throw new IllegalArgumentException("wrong hash");
// 3. If emBits < 8.hLen + 8.sLen + 9, output 'encoding error' and stop.
if (emBits < (8 * hLen + 8 * sLen + 9))
- {
- throw new IllegalArgumentException("encoding error");
- }
+ throw new IllegalArgumentException("encoding error");
int emLen = (emBits + 7) / 8;
// 4. Generate a random octet string salt of length sLen; if sLen = 0,
// then salt is the empty string.
synchronized (hash)
{
for (i = 0; i < 8; i++)
- {
- hash.update((byte) 0x00);
- }
+ hash.update((byte) 0x00);
+
hash.update(mHash, 0, hLen);
hash.update(salt, 0, sLen);
H = hash.digest();
System.arraycopy(salt, 0, DB, emLen - sLen - hLen - 1, sLen);
// 9. Let dbMask = MGF(H, emLen - hLen - 1).
byte[] dbMask = MGF(H, emLen - hLen - 1);
- if (DEBUG && debuglevel > 8)
+ if (Configuration.DEBUG)
{
- debug("dbMask (encode): " + Util.toString(dbMask));
- debug("DB (encode): " + Util.toString(DB));
+ log.fine("dbMask (encode): " + Util.toString(dbMask));
+ log.fine("DB (encode): " + Util.toString(DB));
}
// 10. Let maskedDB = DB XOR dbMask.
for (i = 0; i < DB.length; i++)
- {
- DB[i] = (byte) (DB[i] ^ dbMask[i]);
- }
+ DB[i] = (byte)(DB[i] ^ dbMask[i]);
// 11. Set the leftmost 8emLen - emBits bits of the leftmost octet in
// maskedDB to zero.
DB[0] &= (0xFF >>> (8 * emLen - emBits));
}
/**
- * <p>The decoding operation EMSA-PSS-Decode recovers the message hash from
- * an encoded message <code>EM</code> and compares it to the hash of
- * <code>M</code>.</p>
- *
+ * The decoding operation EMSA-PSS-Decode recovers the message hash from an
+ * encoded message <code>EM</code> and compares it to the hash of
+ * <code>M</code>.
+ *
* @param mHash the byte sequence resulting from applying the message digest
- * algorithm Hash to the message <i>M</i>.
+ * algorithm Hash to the message <i>M</i>.
* @param EM the <i>encoded message</i>, an octet string of length
- * <code>emLen = CEILING(emBits/8).
+ * <code>emLen = CEILING(emBits/8).
* @param emBits the maximal bit length of the integer OS2IP(EM), at least
* <code>8.hLen + 8.sLen + 9</code>.
* @param sLen the length, in octets, of the expected salt.
*/
public boolean decode(byte[] mHash, byte[] EM, int emBits, int sLen)
{
- if (DEBUG && debuglevel > 8)
+ if (Configuration.DEBUG)
{
- debug("mHash: " + Util.toString(mHash));
- debug("EM: " + Util.toString(EM));
- debug("emBits: " + String.valueOf(emBits));
- debug("sLen: " + String.valueOf(sLen));
+ log.fine("mHash: " + Util.toString(mHash));
+ log.fine("EM: " + Util.toString(EM));
+ log.fine("emBits: " + String.valueOf(emBits));
+ log.fine("sLen: " + String.valueOf(sLen));
}
if (sLen < 0)
- {
- throw new IllegalArgumentException("sLen");
- }
-
+ throw new IllegalArgumentException("sLen");
// 1. If the length of M is greater than the input limitation for the hash
- // function (2**61 ? 1 octets for SHA-1) then output 'inconsistent' and
- // stop.
+ // function (2**61 ? 1 octets for SHA-1) then output 'inconsistent' and
+ // stop.
// 2. Let mHash = Hash(M), an octet string of length hLen.
if (hLen != mHash.length)
{
- if (DEBUG && debuglevel > 8)
- {
- debug("hLen != mHash.length; hLen: " + String.valueOf(hLen));
- }
+ if (Configuration.DEBUG)
+ log.fine("hLen != mHash.length; hLen: " + String.valueOf(hLen));
throw new IllegalArgumentException("wrong hash");
}
// 3. If emBits < 8.hLen + 8.sLen + 9, output 'decoding error' and stop.
if (emBits < (8 * hLen + 8 * sLen + 9))
{
- if (DEBUG && debuglevel > 8)
- {
- debug("emBits < (8hLen + 8sLen + 9); sLen: " + String.valueOf(sLen));
- }
+ if (Configuration.DEBUG)
+ log.fine("emBits < (8hLen + 8sLen + 9); sLen: "
+ + String.valueOf(sLen));
throw new IllegalArgumentException("decoding error");
}
int emLen = (emBits + 7) / 8;
// 4. If the rightmost octet of EM does not have hexadecimal value bc,
- // output 'inconsistent' and stop.
+ // output 'inconsistent' and stop.
if ((EM[EM.length - 1] & 0xFF) != 0xBC)
{
- if (DEBUG && debuglevel > 8)
- {
- debug("EM does not end with 0xBC");
- }
+ if (Configuration.DEBUG)
+ log.fine("EM does not end with 0xBC");
return false;
}
// 5. Let maskedDB be the leftmost emLen ? hLen ? 1 octets of EM, and let
- // H be the next hLen octets.
+ // H be the next hLen octets.
// 6. If the leftmost 8.emLen ? emBits bits of the leftmost octet in
- // maskedDB are not all equal to zero, output 'inconsistent' and stop.
+ // maskedDB are not all equal to zero, output 'inconsistent' and stop.
if ((EM[0] & (0xFF << (8 - (8 * emLen - emBits)))) != 0)
{
- if (DEBUG && debuglevel > 8)
- {
- debug("Leftmost 8emLen - emBits bits of EM are not 0s");
- }
+ if (Configuration.DEBUG)
+ log.fine("Leftmost 8emLen - emBits bits of EM are not 0s");
return false;
}
byte[] DB = new byte[emLen - hLen - 1];
// 8. Let DB = maskedDB XOR dbMask.
int i;
for (i = 0; i < DB.length; i++)
- {
- DB[i] = (byte) (DB[i] ^ dbMask[i]);
- }
+ DB[i] = (byte)(DB[i] ^ dbMask[i]);
// 9. Set the leftmost 8.emLen ? emBits bits of DB to zero.
DB[0] &= (0xFF >>> (8 * emLen - emBits));
- if (DEBUG && debuglevel > 8)
+ if (Configuration.DEBUG)
{
- debug("dbMask (decode): " + Util.toString(dbMask));
- debug("DB (decode): " + Util.toString(DB));
+ log.fine("dbMask (decode): " + Util.toString(dbMask));
+ log.fine("DB (decode): " + Util.toString(DB));
}
// 10. If the emLen -hLen -sLen -2 leftmost octets of DB are not zero or
- // if the octet at position emLen -hLen -sLen -1 is not equal to 0x01,
- // output 'inconsistent' and stop.
+ // if the octet at position emLen -hLen -sLen -1 is not equal to 0x01,
+ // output 'inconsistent' and stop.
// IMPORTANT (rsn): this is an error in the specs, the index of the 0x01
- // byte should be emLen -hLen -sLen -2 and not -1! authors have been
- // advised
+ // byte should be emLen -hLen -sLen -2 and not -1! authors have been advised
for (i = 0; i < (emLen - hLen - sLen - 2); i++)
{
if (DB[i] != 0)
{
- if (DEBUG && debuglevel > 8)
- {
- debug("DB[" + String.valueOf(i) + "] != 0x00");
- }
+ if (Configuration.DEBUG)
+ log.fine("DB[" + String.valueOf(i) + "] != 0x00");
return false;
}
}
if (DB[i] != 0x01)
{ // i == emLen -hLen -sLen -2
- if (DEBUG && debuglevel > 8)
- {
- debug("DB's byte at position (emLen -hLen -sLen -2); i.e. "
- + String.valueOf(i) + " is not 0x01");
- }
+ if (Configuration.DEBUG)
+ log.fine("DB's byte at position (emLen -hLen -sLen -2); i.e. "
+ + String.valueOf(i) + " is not 0x01");
return false;
}
// 11. Let salt be the last sLen octets of DB.
byte[] salt = new byte[sLen];
System.arraycopy(DB, DB.length - sLen, salt, 0, sLen);
// 12. Let M0 = 00 00 00 00 00 00 00 00 || mHash || salt;
- // M0 is an octet string of length 8 + hLen + sLen with eight initial
- // zero octets.
+ // M0 is an octet string of length 8 + hLen + sLen with eight initial
+ // zero octets.
// 13. Let H0 = Hash(M0), an octet string of length hLen.
byte[] H0;
synchronized (hash)
{
for (i = 0; i < 8; i++)
- {
- hash.update((byte) 0x00);
- }
+ hash.update((byte) 0x00);
+
hash.update(mHash, 0, hLen);
hash.update(salt, 0, sLen);
H0 = hash.digest();
return Arrays.equals(H, H0);
}
- // helper methods ----------------------------------------------------------
-
/**
- * <p>A mask generation function takes an octet string of variable length
- * and a desired output length as input, and outputs an octet string of the
- * desired length. There may be restrictions on the length of the input and
- * output octet strings, but such bounds are generally very large. Mask
- * generation functions are deterministic; the octet string output is
- * completely determined by the input octet string. The output of a mask
- * generation function should be pseudorandom, that is, it should be
- * infeasible to predict, given one part of the output but not the input,
- * another part of the output. The provable security of RSA-PSS relies on
- * the random nature of the output of the mask generation function, which in
- * turn relies on the random nature of the underlying hash function.</p>
- *
+ * A mask generation function takes an octet string of variable length and a
+ * desired output length as input, and outputs an octet string of the desired
+ * length. There may be restrictions on the length of the input and output
+ * octet strings, but such bounds are generally very large. Mask generation
+ * functions are deterministic; the octet string output is completely
+ * determined by the input octet string. The output of a mask generation
+ * function should be pseudorandom, that is, it should be infeasible to
+ * predict, given one part of the output but not the input, another part of
+ * the output. The provable security of RSA-PSS relies on the random nature of
+ * the output of the mask generation function, which in turn relies on the
+ * random nature of the underlying hash function.
+ *
* @param Z a seed.
* @param l the desired output length in octets.
* @return the mask.
* @exception IllegalArgumentException if the desired output length is too
- * long.
+ * long.
*/
private byte[] MGF(byte[] Z, int l)
{
// 1. If l > (2**32).hLen, output 'mask too long' and stop.
if (l < 1 || (l & 0xFFFFFFFFL) > ((hLen & 0xFFFFFFFFL) << 32L))
- {
- throw new IllegalArgumentException("mask too long");
- }
+ throw new IllegalArgumentException("mask too long");
// 2. Let T be the empty octet string.
byte[] result = new byte[l];
// 3. For i = 0 to CEILING(l/hLen) ? 1, do
int length;
for (int i = 0; i < limit; i++)
{
- // 3.1 Convert i to an octet string C of length 4 with the primitive
- // I2OSP: C = I2OSP(i, 4).
- // 3.2 Concatenate the hash of the seed Z and C to the octet string T:
- // T = T || Hash(Z || C)
+ // 3.1 Convert i to an octet string C of length 4 with the primitive
+ // I2OSP: C = I2OSP(i, 4).
+ // 3.2 Concatenate the hash of the seed Z and C to the octet string T:
+ // T = T || Hash(Z || C)
hashZC = (IMessageDigest) hashZ.clone();
- hashZC.update((byte) (i >>> 24));
- hashZC.update((byte) (i >>> 16));
- hashZC.update((byte) (i >>> 8));
+ hashZC.update((byte)(i >>> 24));
+ hashZC.update((byte)(i >>> 16));
+ hashZC.update((byte)(i >>> 8));
hashZC.update((byte) i);
t = hashZC.digest();
length = l - sofar;
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