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-rw-r--r--src/se/leap/leapclient/LeapSRPSession.java236
1 files changed, 134 insertions, 102 deletions
diff --git a/src/se/leap/leapclient/LeapSRPSession.java b/src/se/leap/leapclient/LeapSRPSession.java
index cecceed6..abdf6b2c 100644
--- a/src/se/leap/leapclient/LeapSRPSession.java
+++ b/src/se/leap/leapclient/LeapSRPSession.java
@@ -18,7 +18,6 @@ public class LeapSRPSession {
private BigInteger g;
private BigInteger x;
private BigInteger v;
- private byte[] s;
private BigInteger a;
private BigInteger A;
private byte[] K;
@@ -49,16 +48,14 @@ public class LeapSRPSession {
8 bytes in length.
*/
public LeapSRPSession(String username, char[] password, SRPParameters params,
- byte[] abytes)
- {
- try
- {
+ byte[] abytes) {
+ try {
// Initialize the secure random number and message digests
Util.init();
}
- catch(NoSuchAlgorithmException e)
- {
+ catch(NoSuchAlgorithmException e) {
}
+
this.params = params;
this.g = new BigInteger(1, params.g);
byte[] N_bytes = Util.trim(params.N);
@@ -75,46 +72,113 @@ public class LeapSRPSession {
}
// Calculate x = H(s | H(U | ':' | password))
- byte[] salt_bytes = params.s;
- salt_bytes = Util.trim(salt_bytes);
+ byte[] salt_bytes = Util.trim(params.s);
byte[] xb = calculatePasswordHash(username, password, salt_bytes);
- xb = Util.trim(xb);
this.x = new BigInteger(1, xb);
// Calculate v = kg^x mod N
- this.v = calculateV();
- String v_string = v.toString(16);
+ String k_string = "bf66c44a428916cad64aa7c679f3fd897ad4c375e9bbb4cbf2f5de241d618ef0";
+ this.v = calculateV(k_string);
+ //String v_string = v.toString(16);
serverHash = newDigest();
clientHash = newDigest();
// H(N)
- byte[] hn = newDigest().digest(N_bytes);
+ byte[] digest_of_n = newDigest().digest(N_bytes);
+
// H(g)
- byte[] hg = newDigest().digest(params.g);
+ byte[] digest_of_g = newDigest().digest(params.g);
+
// clientHash = H(N) xor H(g)
- byte[] hxg = xor(hn, hg, hg.length);
- String hxg_string = new BigInteger(1, hxg).toString(16);
- hxg = Util.trim(hxg);
- clientHash.update(hxg); // OK
+ byte[] xor_digest = xor(digest_of_n, digest_of_g, digest_of_g.length);
+ //String hxg_string = new BigInteger(1, xor_digest).toString(16);
+ clientHash.update(xor_digest);
+
// clientHash = H(N) xor H(g) | H(U)
- byte[] username_bytes = username.getBytes();
- username_bytes = Util.trim(username_bytes);
- byte[] username_digest = newDigest().digest(username_bytes);
+ byte[] username_digest = newDigest().digest(Util.trim(username.getBytes()));
username_digest = Util.trim(username_digest);
- String username_digest_string = new BigInteger(1, username_digest).toString(16);
- clientHash.update(username_digest); // OK
+ //String username_digest_string = new BigInteger(1, username_digest).toString(16);
+ clientHash.update(username_digest);
+
// clientHash = H(N) xor H(g) | H(U) | s
- String salt_string = new BigInteger(1, salt_bytes).toString(16);
- clientHash.update(salt_bytes); // OK
+ //String salt_string = new BigInteger(1, salt_bytes).toString(16);
+ clientHash.update(salt_bytes);
+
K = null;
}
- private BigInteger calculateV() {
- BigInteger k = new BigInteger("bf66c44a428916cad64aa7c679f3fd897ad4c375e9bbb4cbf2f5de241d618ef0", 16);
+ /**
+ * Calculates the parameter x of the SRP-6a algorithm.
+ * @param username
+ * @param password
+ * @param salt the salt of the user
+ * @return x
+ */
+ public byte[] calculatePasswordHash(String username, char[] password, byte[] salt)
+ {
+ // Calculate x = H(s | H(U | ':' | password))
+ MessageDigest x_digest = newDigest();
+
+ // Try to convert the username to a byte[] using UTF-8
+ byte[] user = null;
+ byte[] colon = {};
+ try {
+ user = Util.trim(username.getBytes("UTF-8"));
+ colon = Util.trim(":".getBytes("UTF-8"));
+ }
+ catch(UnsupportedEncodingException e) {
+ // Use the default platform encoding
+ user = Util.trim(username.getBytes());
+ colon = Util.trim(":".getBytes());
+ }
+
+ byte[] passBytes = new byte[2*password.length];
+ int passBytesLength = 0;
+ for(int p = 0; p < password.length; p++) {
+ int c = (password[p] & 0x00FFFF);
+ // The low byte of the char
+ byte b0 = (byte) (c & 0x0000FF);
+ // The high byte of the char
+ byte b1 = (byte) ((c & 0x00FF00) >> 8);
+ passBytes[passBytesLength ++] = b0;
+ // Only encode the high byte if c is a multi-byte char
+ if( c > 255 )
+ passBytes[passBytesLength ++] = b1;
+ }
+
+ // Build the hash
+ x_digest.update(user);
+ x_digest.update(colon);
+ x_digest.update(passBytes, 0, passBytesLength);
+ byte[] h = x_digest.digest();
+ //h = Util.trim(h);
+
+ x_digest.reset();
+ x_digest.update(salt);
+ x_digest.update(h);
+ byte[] x_digest_bytes = Util.trim(x_digest.digest());
+
+ return x_digest_bytes;
+ }
+
+ /**
+ * Calculates the parameter V of the SRP-6a algorithm.
+ * @param k_string constant k predefined by the SRP server implementation.
+ * @return the value of V
+ */
+ private BigInteger calculateV(String k_string) {
+ BigInteger k = new BigInteger(k_string, 16);
return k.multiply(g.modPow(x, N)); // g^x % N
}
+ public byte[] xor(byte[] b1, byte[] b2, int length)
+ {
+ //TODO Check if length matters in the order, when b2 is smaller than b1 or viceversa
+ byte[] xor_digest = new BigInteger(1, b1).xor(new BigInteger(1, b2)).toByteArray();
+ return Util.trim(xor_digest);
+ }
+
/**
* @returns The exponential residue (parameter A) to be sent to the server.
*/
@@ -130,60 +194,81 @@ public class LeapSRPSession {
} while(a.compareTo(one) <= 0);
}
A = g.modPow(a, N);
- Abytes = A.toByteArray();
- String Abytes_string = new BigInteger(1, Abytes).toString(16);
- Abytes = Util.trim(Abytes);
+ Abytes = Util.trim(A.toByteArray());
+ //String Abytes_string = new BigInteger(1, Abytes).toString(16);
+
// clientHash = H(N) xor H(g) | H(U) | A
- clientHash.update(Abytes); // Begins with 0: second case
+ clientHash.update(Abytes);
+
// serverHash = A
serverHash.update(Abytes);
}
return Abytes;
}
+ /**
+ * Calculates the parameter M1, to be sent to the SRP server.
+ * It also updates hashes of client and server for further calculations in other methods.
+ * @param Bbytes the parameter received from the server, in bytes
+ * @return the parameter M1
+ * @throws NoSuchAlgorithmException
+ */
public byte[] response(byte[] Bbytes) throws NoSuchAlgorithmException {
// clientHash = H(N) xor H(g) | H(U) | s | A | B
- Bbytes = Util.trim(Bbytes); // Begins with 0: first case, second case
- String Bbytes_string = new BigInteger(1, Bbytes).toString(16);
- clientHash.update(Bbytes); // OK
+ Bbytes = Util.trim(Bbytes);
+ //String Bbytes_string = new BigInteger(1, Bbytes).toString(16);
+ clientHash.update(Bbytes);
+
// Calculate S = (B - kg^x) ^ (a + u * x) % N
BigInteger S = calculateS(Bbytes);
- byte[] S_bytes = S.toByteArray();
- S_bytes = Util.trim(S_bytes); // Begins with 0: first case
- String S_bytes_string = new BigInteger(1, S_bytes).toString(16);
+ byte[] S_bytes = Util.trim(S.toByteArray());
+ //String S_bytes_string = new BigInteger(1, S_bytes).toString(16);
+
// K = SessionHash(S)
String hash_algorithm = params.hashAlgorithm;
MessageDigest sessionDigest = MessageDigest.getInstance(hash_algorithm);
K = sessionDigest.digest(S_bytes);
//K = Util.trim(K);
- String K_bytes_string = new BigInteger(1, K).toString(16);
+ //String K_bytes_string = new BigInteger(1, K).toString(16);
// clientHash = H(N) xor H(g) | H(U) | A | B | K
clientHash.update(K);
byte[] M1 = clientHash.digest();
+
// serverHash = Astr + M + K
serverHash.update(M1);
serverHash.update(K);
return M1;
}
-
+ /**
+ * It calculates the parameter S used by response() to obtain session hash K.
+ * @param Bbytes the parameter received from the server, in bytes
+ * @return the parameter S
+ */
private BigInteger calculateS(byte[] Bbytes) {
byte[] Abytes = Util.trim(A.toByteArray());
- byte[] ub = getU(Abytes, Bbytes);
+ byte[] u_bytes = getU(Abytes, Bbytes);
//ub = Util.trim(ub);
BigInteger B = new BigInteger(1, Bbytes);
- BigInteger u = new BigInteger(1, ub);
- String u_string = u.toString(16);
- BigInteger B_v = B.subtract(v);
+ BigInteger u = new BigInteger(1, u_bytes);
+ //String u_string = u.toString(16);
+
+ BigInteger B_minus_v = B.subtract(v);
BigInteger a_ux = a.add(u.multiply(x));
- String a_ux_string = a_ux.toString(16);
- BigInteger S = B_v.modPow(a_ux, N);
+ //String a_ux_string = a_ux.toString(16);
+ BigInteger S = B_minus_v.modPow(a_ux, N);
return S;
}
+ /**
+ * It calculates the parameter u used by calculateS to obtain S.
+ * @param Abytes the exponential residue sent to the server
+ * @param Bbytes the parameter received from the server, in bytes
+ * @return
+ */
public byte[] getU(byte[] Abytes, byte[] Bbytes) {
MessageDigest u_digest = newDigest();
u_digest.update(Abytes);
@@ -210,15 +295,13 @@ public class LeapSRPSession {
*/
public byte[] getSessionKey() throws SecurityException
{
- SecurityManager sm = System.getSecurityManager();
- if( sm != null )
- {
- SRPPermission p = new SRPPermission("getSessionKey");
- sm.checkPermission(p);
- }
return K;
}
+
+ /**
+ * @return a new SHA-256 digest.
+ */
public MessageDigest newDigest()
{
MessageDigest md = null;
@@ -229,55 +312,4 @@ public class LeapSRPSession {
}
return md;
}
-
- public byte[] calculatePasswordHash(String username, char[] password, byte[] salt)
- {
- // Calculate x = H(s | H(U | ':' | password))
- MessageDigest xd = newDigest();
- // Try to convert the username to a byte[] using UTF-8
- byte[] user = null;
- byte[] colon = {};
- try {
- user = username.getBytes("UTF-8");
- colon = ":".getBytes("UTF-8");
- }
- catch(UnsupportedEncodingException e) {
- // Use the default platform encoding
- user = username.getBytes();
- colon = ":".getBytes();
- }
- user = Util.trim(user);
- colon = Util.trim(colon);
- byte[] passBytes = new byte[2*password.length];
- int passBytesLength = 0;
- for(int p = 0; p < password.length; p ++) {
- int c = (password[p] & 0x00FFFF);
- // The low byte of the char
- byte b0 = (byte) (c & 0x0000FF);
- // The high byte of the char
- byte b1 = (byte) ((c & 0x00FF00) >> 8);
- passBytes[passBytesLength ++] = b0;
- // Only encode the high byte if c is a multi-byte char
- if( c > 255 )
- passBytes[passBytesLength ++] = b1;
- }
-
- // Build the hash
- xd.update(user);
- xd.update(colon);
- xd.update(passBytes, 0, passBytesLength);
- byte[] h = xd.digest();
- //h = Util.trim(h);
- xd.reset();
- xd.update(salt);
- xd.update(h);
- byte[] xb = xd.digest();
- return xb;
- }
-
- public byte[] xor(byte[] b1, byte[] b2, int length)
- {
- //TODO Check if length matters in the order, when b2 is smaller than b1 or viceversa
- return new BigInteger(1, b1).xor(new BigInteger(1, b2)).toByteArray();
- }
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-09 14:09:13 +0000