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Diffstat (limited to 'core/src/main/java/com/att/cadi/Symm.java')
| -rw-r--r-- | core/src/main/java/com/att/cadi/Symm.java | 812 |
1 files changed, 812 insertions, 0 deletions
diff --git a/core/src/main/java/com/att/cadi/Symm.java b/core/src/main/java/com/att/cadi/Symm.java new file mode 100644 index 0000000..0b34b58 --- /dev/null +++ b/core/src/main/java/com/att/cadi/Symm.java @@ -0,0 +1,812 @@ +/*******************************************************************************
+ * ============LICENSE_START====================================================
+ * * org.onap.aai
+ * * ===========================================================================
+ * * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
+ * * Copyright © 2017 Amdocs
+ * * ===========================================================================
+ * * Licensed under the Apache License, Version 2.0 (the "License");
+ * * you may not use this file except in compliance with the License.
+ * * You may obtain a copy of the License at
+ * *
+ * * http://www.apache.org/licenses/LICENSE-2.0
+ * *
+ * * Unless required by applicable law or agreed to in writing, software
+ * * distributed under the License is distributed on an "AS IS" BASIS,
+ * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * * See the License for the specific language governing permissions and
+ * * limitations under the License.
+ * * ============LICENSE_END====================================================
+ * *
+ * * ECOMP is a trademark and service mark of AT&T Intellectual Property.
+ * *
+ ******************************************************************************/
+package com.att.cadi;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.Random;
+
+import javax.crypto.CipherInputStream;
+import javax.crypto.CipherOutputStream;
+
+import com.att.cadi.Access.Level;
+import com.att.cadi.config.Config;
+
+/**
+ * Key Conversion, primarily "Base64"
+ *
+ * Base64 is required for "Basic Authorization", which is an important part of the overall CADI Package.
+ *
+ * Note: This author found that there is not a "standard" library for Base64 conversion within Java.
+ * The source code implementations available elsewhere were surprisingly inefficient, requiring, for
+ * instance, multiple string creation, on a transaction pass. Integrating other packages that might be
+ * efficient enough would put undue Jar File Dependencies given this Framework should have none-but-Java
+ * dependencies.
+ *
+ * The essential algorithm is good for a symmetrical key system, as Base64 is really just
+ * a symmetrical key that everyone knows the values.
+ *
+ * This code is quite fast, taking about .016 ms for encrypting, decrypting and even .08 for key
+ * generation. The speed quality, especially of key generation makes this a candidate for a short term token
+ * used for identity.
+ *
+ * It may be used to easily avoid placing Clear-Text passwords in configurations, etc. and contains
+ * supporting functions such as 2048 keyfile generation (see keygen). This keyfile should, of course,
+ * be set to "400" (Unix) and protected as any other mechanism requires.
+ *
+ * However, this algorithm has not been tested against hackers. Until such a time, utilize more tested
+ * packages to protect Data, especially sensitive data at rest (long term).
+ *
+ */
+public class Symm {
+ private static final byte[] DOUBLE_EQ = new byte[] {'=','='};
+ public static final String ENC = "enc:";
+ private static final SecureRandom random = new SecureRandom();
+
+ public final char[] codeset;
+ private final int splitLinesAt;
+ private final String encoding;
+ private final Convert convert;
+ private final boolean endEquals;
+ //Note: AES Encryption is not Thread Safe. It is Synchronized
+ private static AES aes = null; // only initialized from File, and only if needed for Passwords
+
+ /**
+ * This is the standard base64 Key Set.
+ * RFC 2045
+ */
+ public static final Symm base64 = new Symm(
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray()
+ ,76, Config.UTF_8,true);
+
+ public static final Symm base64noSplit = new Symm(
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray()
+ ,Integer.MAX_VALUE, Config.UTF_8,true);
+
+ /**
+ * This is the standard base64 set suitable for URLs and Filenames
+ * RFC 4648
+ */
+ public static final Symm base64url = new Symm(
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".toCharArray()
+ ,76, Config.UTF_8,true);
+
+ /**
+ * A Password set, using US-ASCII
+ * RFC 4648
+ */
+ public static final Symm encrypt = new Symm(base64url.codeset,1024, "US-ASCII", false);
+
+ /**
+ * A typical set of Password Chars
+ * Note, this is too large to fit into the algorithm. Only use with PassGen
+ */
+ private static char passChars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+!@#$%^&*(){}[]?:;,.".toCharArray();
+
+
+
+ /**
+ * Use this to create special case Case Sets and/or Line breaks
+ *
+ * If you don't know why you need this, use the Singleton Method
+ *
+ * @param codeset
+ * @param split
+ */
+ public Symm(char[] codeset, int split, String charset, boolean useEndEquals) {
+ this.codeset = codeset;
+ splitLinesAt = split;
+ encoding = charset;
+ endEquals = useEndEquals;
+ char prev = 0, curr=0, first = 0;
+ int offset=Integer.SIZE; // something that's out of range for integer array
+
+ // There can be time efficiencies gained when the underlying keyset consists mainly of ordered
+ // data (i.e. abcde...). Therefore, we'll quickly analyze the keyset. If it proves to have
+ // too much entropy, the "Unordered" algorithm, which is faster in such cases is used.
+ ArrayList<int[]> la = new ArrayList<int[]>();
+ for(int i=0;i<codeset.length;++i) {
+ curr = codeset[i];
+ if(prev+1==curr) { // is next character in set
+ prev = curr;
+ } else {
+ if(offset!=Integer.SIZE) { // add previous range
+ la.add(new int[]{first,prev,offset});
+ }
+ first = prev = curr;
+ offset = curr-i;
+ }
+ }
+ la.add(new int[]{first,curr,offset});
+ if(la.size()>codeset.length/3) {
+ convert = new Unordered(codeset);
+ } else { // too random to get speed enhancement from range algorithm
+ int[][] range = new int[la.size()][];
+ la.toArray(range);
+ convert = new Ordered(range);
+ }
+ }
+
+ public Symm copy(int lines) {
+ return new Symm(codeset,lines,encoding,endEquals);
+ }
+
+ // Only used by keygen, which is intentionally randomized. Therefore, always use unordered
+ private Symm(char[] codeset, Symm parent) {
+ this.codeset = codeset;
+ splitLinesAt = parent.splitLinesAt;
+ endEquals = parent.endEquals;
+ encoding = parent.encoding;
+ convert = new Unordered(codeset);
+ }
+
+ /**
+ * Obtain the base64() behavior of this class, for use in standard BASIC AUTH mechanism, etc.
+ * @return
+ */
+ @Deprecated
+ public static final Symm base64() {
+ return base64;
+ }
+
+ /**
+ * Obtain the base64() behavior of this class, for use in standard BASIC AUTH mechanism, etc.
+ * No Line Splitting
+ * @return
+ */
+ @Deprecated
+ public static final Symm base64noSplit() {
+ return base64noSplit;
+ }
+
+ /**
+ * Obtain the base64 "URL" behavior of this class, for use in File Names, etc. (no "/")
+ */
+ @Deprecated
+ public static final Symm base64url() {
+ return base64url;
+ }
+
+ /**
+ * Obtain a special ASCII version for Scripting, with base set of base64url use in File Names, etc. (no "/")
+ */
+ public static final Symm baseCrypt() {
+ return encrypt;
+ }
+
+ /*
+ * Note: AES Encryption is NOT thread-safe. Must surround entire use with synchronized
+ */
+ private synchronized void exec(AESExec exec) throws IOException {
+ if(aes == null) {
+ try {
+ byte[] bytes = new byte[AES.AES_KEY_SIZE/8];
+ int offset = (Math.abs(codeset[0])+47)%(codeset.length-bytes.length);
+ for(int i=0;i<bytes.length;++i) {
+ bytes[i] = (byte)codeset[i+offset];
+ }
+ aes = new AES(bytes,0,bytes.length);
+ } catch (Exception e) {
+ throw new IOException(e);
+ }
+ }
+ exec.exec(aes);
+ }
+
+ private static interface AESExec {
+ public void exec(AES aes) throws IOException;
+ }
+
+ public byte[] encode(byte[] toEncrypt) throws IOException {
+ ByteArrayOutputStream baos = new ByteArrayOutputStream((int)(toEncrypt.length*1.25));
+ encode(new ByteArrayInputStream(toEncrypt),baos);
+ return baos.toByteArray();
+ }
+
+ public byte[] decode(byte[] encrypted) throws IOException {
+ ByteArrayOutputStream baos = new ByteArrayOutputStream((int)(encrypted.length*1.25));
+ decode(new ByteArrayInputStream(encrypted),baos);
+ return baos.toByteArray();
+ }
+
+ /**
+ * Helper function for String API of "Encode"
+ * use "getBytes" with appropriate char encoding, etc.
+ *
+ * @param str
+ * @return
+ * @throws IOException
+ */
+ public String encode(String str) throws IOException {
+ byte[] array;
+ try {
+ array = str.getBytes(encoding);
+ } catch (IOException e) {
+ array = str.getBytes(); // take default
+ }
+ // Calculate expected size to avoid any buffer expansion copies within the ByteArrayOutput code
+ ByteArrayOutputStream baos = new ByteArrayOutputStream((int)(array.length*1.363)); // account for 4 bytes for 3 and a byte or two more
+
+ encode(new ByteArrayInputStream(array),baos);
+ return baos.toString(encoding);
+ }
+
+ /**
+ * Helper function for the String API of "Decode"
+ * use "getBytes" with appropriate char encoding, etc.
+ * @param str
+ * @return
+ * @throws IOException
+ */
+ public String decode(String str) throws IOException {
+ byte[] array;
+ try {
+ array = str.getBytes(encoding);
+ } catch (IOException e) {
+ array = str.getBytes(); // take default
+ }
+ // Calculate expected size to avoid any buffer expansion copies within the ByteArrayOutput code
+ ByteArrayOutputStream baos = new ByteArrayOutputStream((int)(array.length*.76)); // Decoding is 3 bytes for 4. Allocate slightly more than 3/4s
+ decode(new ByteArrayInputStream(array), baos);
+ return baos.toString(encoding);
+ }
+
+ /**
+ * Convenience Function
+ *
+ * encode String into InputStream and call encode(InputStream, OutputStream)
+ *
+ * @param string
+ * @param out
+ * @throws IOException
+ */
+ public void encode(String string, OutputStream out) throws IOException {
+ encode(new ByteArrayInputStream(string.getBytes()),out);
+ }
+
+ /**
+ * Convenience Function
+ *
+ * encode String into InputStream and call decode(InputStream, OutputStream)
+ *
+ * @param string
+ * @param out
+ * @throws IOException
+ */
+ public void decode(String string, OutputStream out) throws IOException {
+ decode(new ByteArrayInputStream(string.getBytes()),out);
+ }
+
+ public void encode(InputStream is, OutputStream os, byte[] prefix) throws IOException {
+ os.write(prefix);
+ encode(is,os);
+ }
+
+ /**
+ * encode InputStream onto Output Stream
+ *
+ * @param is
+ * @param estimate
+ * @return
+ * @throws IOException
+ */
+ public void encode(InputStream is, OutputStream os) throws IOException {
+ // StringBuilder sb = new StringBuilder((int)(estimate*1.255)); // try to get the right size of StringBuilder from start.. slightly more than 1.25 times
+ int prev=0;
+ int read, idx=0, line=0;
+ boolean go;
+ do {
+ read = is.read();
+ if(go = read>=0) {
+ if(line>=splitLinesAt) {
+ os.write('\n');
+ line = 0;
+ }
+ switch(++idx) { // 1 based reading, slightly faster ++
+ case 1: // ptr is the first 6 bits of read
+ os.write(codeset[read>>2]);
+ prev = read;
+ break;
+ case 2: // ptr is the last 2 bits of prev followed by the first 4 bits of read
+ os.write(codeset[((prev & 0x03)<<4) | (read>>4)]);
+ prev = read;
+ break;
+ default: //(3+)
+ // Char 1 is last 4 bits of prev plus the first 2 bits of read
+ // Char 2 is the last 6 bits of read
+ os.write(codeset[(((prev & 0xF)<<2) | (read>>6))]);
+ if(line==splitLinesAt) { // deal with line splitting for two characters
+ os.write('\n');
+ line=0;
+ }
+ os.write(codeset[(read & 0x3F)]);
+ ++line;
+ idx = 0;
+ prev = 0;
+ }
+ ++line;
+ } else { // deal with any remaining bits from Prev, then pad
+ switch(idx) {
+ case 1: // just the last 2 bits of prev
+ os.write(codeset[(prev & 0x03)<<4]);
+ if(endEquals)os.write(DOUBLE_EQ);
+ break;
+ case 2: // just the last 4 bits of prev
+ os.write(codeset[(prev & 0xF)<<2]);
+ if(endEquals)os.write('=');
+ break;
+ }
+ idx = 0;
+ }
+
+ } while(go);
+ }
+
+ public void decode(InputStream is, OutputStream os, int skip) throws IOException {
+ is.skip(skip);
+ decode(is,os);
+ }
+
+ /**
+ * Decode InputStream onto OutputStream
+ * @param is
+ * @param os
+ * @throws IOException
+ */
+ public void decode(InputStream is, OutputStream os) throws IOException {
+ int read, idx=0;
+ int prev=0, index;
+ while((read = is.read())>=0) {
+ index = convert.convert(read);
+ if(index>=0) {
+ switch(++idx) { // 1 based cases, slightly faster ++
+ case 1: // index goes into first 6 bits of prev
+ prev = index<<2;
+ break;
+ case 2: // write second 2 bits of into prev, write byte, last 4 bits go into prev
+ os.write((byte)(prev|(index>>4)));
+ prev = index<<4;
+ break;
+ case 3: // first 4 bits of index goes into prev, write byte, last 2 bits go into prev
+ os.write((byte)(prev|(index>>2)));
+ prev = index<<6;
+ break;
+ default: // (3+) | prev and last six of index
+ os.write((byte)(prev|(index&0x3F)));
+ idx = prev = 0;
+ }
+ }
+ };
+ os.flush();
+ }
+
+ /**
+ * Interface to allow this class to choose which algorithm to find index of character in Key
+ *
+ */
+ private interface Convert {
+ public int convert(int read) throws IOException;
+ }
+
+ /**
+ * Ordered uses a range of orders to compare against, rather than requiring the investigation
+ * of every character needed.
+ *
+ */
+ private static final class Ordered implements Convert {
+ private int[][] range;
+ public Ordered(int[][] range) {
+ this.range = range;
+ }
+ public int convert(int read) throws IOException {
+ switch(read) {
+ case -1:
+ case '=':
+ case '\n':
+ return -1;
+ }
+ for(int i=0;i<range.length;++i) {
+ if(read >= range[i][0] && read<=range[i][1]) {
+ return read-range[i][2];
+ }
+ }
+ throw new IOException("Unacceptable Character in Stream");
+ }
+ }
+
+ /**
+ * Unordered, i.e. the key is purposely randomized, simply has to investigate each character
+ * until we find a match.
+ *
+ */
+ private static final class Unordered implements Convert {
+ private char[] codec;
+ public Unordered(char[] codec) {
+ this.codec = codec;
+ }
+ public int convert(int read) throws IOException {
+ switch(read) {
+ case -1:
+ case '=':
+ case '\n':
+ return -1;
+ }
+ for(int i=0;i<codec.length;++i) {
+ if(codec[i]==read)return i;
+ }
+ // don't give clue in Encryption mode
+ throw new IOException("Unacceptable Character in Stream");
+ }
+ }
+
+ /**
+ * Generate a 2048 based Key from which we extract our code base
+ *
+ * @return
+ * @throws IOException
+ */
+ public byte[] keygen() throws IOException {
+ byte inkey[] = new byte[0x600];
+ new SecureRandom().nextBytes(inkey);
+ ByteArrayOutputStream baos = new ByteArrayOutputStream(0x800);
+ base64url.encode(new ByteArrayInputStream(inkey), baos);
+ return baos.toByteArray();
+ }
+
+ // A class allowing us to be less predictable about significant digits (i.e. not picking them up from the
+ // beginning, and not picking them up in an ordered row. Gives a nice 2048 with no visible patterns.
+ private class Obtain {
+ private int last;
+ private int skip;
+ private int length;
+ private byte[] key;
+
+ private Obtain(Symm b64, byte[] key) {
+ skip = Math.abs(key[key.length-13]%key.length);
+ if((key.length&0x1) == (skip&0x1)) { // if both are odd or both are even
+ ++skip;
+ }
+ length = b64.codeset.length;
+ last = 17+length%59; // never start at beginning
+ this.key = key;
+ }
+
+ private int next() {
+ return Math.abs(key[(++last*skip)%key.length])%length;
+ }
+ };
+
+ /**
+ * Obtain a Symm from "keyfile" (Config.KEYFILE) property
+ *
+ * @param acesss
+ * @return
+ */
+ public static Symm obtain(Access access) {
+ Symm symm = Symm.baseCrypt();
+
+ String keyfile = access.getProperty(Config.CADI_KEYFILE,null);
+ if(keyfile!=null) {
+ File file = new File(keyfile);
+ try {
+ access.log(Level.INIT, Config.CADI_KEYFILE,"points to",file.getCanonicalPath());
+ } catch (IOException e1) {
+ access.log(Level.INIT, Config.CADI_KEYFILE,"points to",file.getAbsolutePath());
+ }
+ if(file.exists()) {
+ try {
+ FileInputStream fis = new FileInputStream(file);
+ try {
+ symm = Symm.obtain(fis);
+ } finally {
+ try {
+ fis.close();
+ } catch (IOException e) {
+ }
+ }
+ } catch (IOException e) {
+ access.log(e, "Cannot load keyfile");
+ }
+ }
+ }
+ return symm;
+ }
+ /**
+ * Create a new random key
+ */
+ public Symm obtain() throws IOException {
+ byte inkey[] = new byte[0x800];
+ new SecureRandom().nextBytes(inkey);
+ return obtain(inkey);
+ }
+
+ /**
+ * Obtain a Symm from 2048 key from a String
+ *
+ * @param key
+ * @return
+ * @throws IOException
+ */
+ public static Symm obtain(String key) throws IOException {
+ return obtain(new ByteArrayInputStream(key.getBytes()));
+ }
+
+ /**
+ * Obtain a Symm from 2048 key from a Stream
+ *
+ * @param is
+ * @return
+ * @throws IOException
+ */
+ public static Symm obtain(InputStream is) throws IOException {
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ try {
+ base64url.decode(is, baos);
+ } catch (IOException e) {
+ // don't give clue
+ throw new IOException("Invalid Key");
+ }
+ byte[] bkey = baos.toByteArray();
+ if(bkey.length<0x88) { // 2048 bit key
+ throw new IOException("Invalid key");
+ }
+ return baseCrypt().obtain(bkey);
+ }
+
+ /**
+ * Convenience for picking up Keyfile
+ *
+ * @param f
+ * @return
+ * @throws IOException
+ */
+ public static Symm obtain(File f) throws IOException {
+ FileInputStream fis = new FileInputStream(f);
+ try {
+ return obtain(fis);
+ } finally {
+ fis.close();
+ }
+ }
+ /**
+ * Decrypt into a String
+ *
+ * Convenience method
+ *
+ * @param password
+ * @return
+ * @throws IOException
+ */
+ public String enpass(String password) throws IOException {
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ enpass(password,baos);
+ return new String(baos.toByteArray());
+ }
+
+ /**
+ * Create an encrypted password, making sure that even short passwords have a minimum length.
+ *
+ * @param password
+ * @param os
+ * @throws IOException
+ */
+ public void enpass(final String password, final OutputStream os) throws IOException {
+ final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ DataOutputStream dos = new DataOutputStream(baos);
+ byte[] bytes = password.getBytes();
+ if(this.getClass().getSimpleName().startsWith("base64")) { // don't expose randomization
+ dos.write(bytes);
+ } else {
+
+ Random r = new SecureRandom();
+ int start = 0;
+ byte b;
+ for(int i=0;i<3;++i) {
+ dos.writeByte(b=(byte)r.nextInt());
+ start+=Math.abs(b);
+ }
+ start%=0x7;
+ for(int i=0;i<start;++i) {
+ dos.writeByte(r.nextInt());
+ }
+ dos.writeInt((int)System.currentTimeMillis());
+ int minlength = Math.min(0x9,bytes.length);
+ dos.writeByte(minlength); // expect truncation
+ if(bytes.length<0x9) {
+ for(int i=0;i<bytes.length;++i) {
+ dos.writeByte(r.nextInt());
+ dos.writeByte(bytes[i]);
+ }
+ // make sure it's long enough
+ for(int i=bytes.length;i<0x9;++i) {
+ dos.writeByte(r.nextInt());
+ }
+ } else {
+ dos.write(bytes);
+ }
+ }
+
+ // 7/21/2016 jg add AES Encryption to the mix
+ exec(new AESExec() {
+ @Override
+ public void exec(AES aes) throws IOException {
+ CipherInputStream cis = aes.inputStream(new ByteArrayInputStream(baos.toByteArray()), true);
+ try {
+ encode(cis,os);
+ } finally {
+ os.flush();
+ cis.close();
+ }
+ }
+ });
+ synchronized(ENC) {
+ }
+ }
+
+ /**
+ * Decrypt a password into a String
+ *
+ * Convenience method
+ *
+ * @param password
+ * @return
+ * @throws IOException
+ */
+ public String depass(String password) throws IOException {
+ if(password==null)return null;
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ depass(password,baos);
+ return new String(baos.toByteArray());
+ }
+
+ /**
+ * Decrypt a password
+ *
+ * Skip Symm.ENC
+ *
+ * @param password
+ * @param os
+ * @return
+ * @throws IOException
+ */
+ public long depass(final String password, final OutputStream os) throws IOException {
+ int offset = password.startsWith(ENC)?4:0;
+ final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ final ByteArrayInputStream bais = new ByteArrayInputStream(password.getBytes(),offset,password.length()-offset);
+ exec(new AESExec() {
+ @Override
+ public void exec(AES aes) throws IOException {
+ CipherOutputStream cos = aes.outputStream(baos, false);
+ decode(bais,cos);
+ cos.close(); // flush
+ }
+ });
+ byte[] bytes = baos.toByteArray();
+ DataInputStream dis = new DataInputStream(new ByteArrayInputStream(bytes));
+ long time;
+ if(this.getClass().getSimpleName().startsWith("base64")) { // don't expose randomization
+ os.write(bytes);
+ time = 0L;
+ } else {
+ int start=0;
+ for(int i=0;i<3;++i) {
+ start+=Math.abs(dis.readByte());
+ }
+ start%=0x7;
+ for(int i=0;i<start;++i) {
+ dis.readByte();
+ }
+ time = (dis.readInt() & 0xFFFF)|(System.currentTimeMillis()&0xFFFF0000);
+ int minlength = dis.readByte();
+ if(minlength<0x9){
+ DataOutputStream dos = new DataOutputStream(os);
+ for(int i=0;i<minlength;++i) {
+ dis.readByte();
+ dos.writeByte(dis.readByte());
+ }
+ } else {
+ int pre =((Byte.SIZE*3+Integer.SIZE+Byte.SIZE)/Byte.SIZE)+start;
+ os.write(bytes, pre, bytes.length-pre);
+ }
+ }
+ return time;
+ }
+
+ public static String randomGen(int numBytes) {
+ return randomGen(passChars,numBytes);
+ }
+
+ public static String randomGen(char[] chars ,int numBytes) {
+ int rint;
+ StringBuilder sb = new StringBuilder(numBytes);
+ for(int i=0;i<numBytes;++i) {
+ rint = random.nextInt(chars.length);
+ sb.append(chars[rint]);
+ }
+ return sb.toString();
+ }
+ // Internal mechanism for helping to randomize placement of characters within a Symm codeset
+ // Based on an incoming data stream (originally created randomly, but can be recreated within
+ // 2048 key), go after a particular place in the new codeset. If that codeset spot is used, then move
+ // right or left (depending on iteration) to find the next available slot. In this way, key generation
+ // is speeded up by only enacting N iterations, but adds a spreading effect of the random number stream, so that keyset is also
+ // shuffled for a good spread. It is, however, repeatable, given the same number set, allowing for
+ // quick recreation when the official stream is actually obtained.
+ public Symm obtain(byte[] key) throws IOException {
+ try {
+ byte[] bytes = new byte[AES.AES_KEY_SIZE/8];
+ int offset = (Math.abs(key[(47%key.length)])+137)%(key.length-bytes.length);
+ for(int i=0;i<bytes.length;++i) {
+ bytes[i] = key[i+offset];
+ }
+
+ aes = new AES(bytes,0,bytes.length);
+ } catch (Exception e) {
+ throw new IOException(e);
+ }
+ int filled = codeset.length;
+ char[] seq = new char[filled];
+ int end = filled--;
+
+ boolean right = true;
+ int index;
+ Obtain o = new Obtain(this,key);
+
+ while(filled>=0) {
+ index = o.next();
+ if(index<0 || index>=codeset.length) {
+ System.out.println("uh, oh");
+ }
+ if(right) { // alternate going left or right to find the next open slot (keeps it from taking too long to hit something)
+ for(int j=index;j<end;++j) {
+ if(seq[j]==0) {
+ seq[j]=codeset[filled];
+ --filled;
+ break;
+ }
+ }
+ right = false;
+ } else {
+ for(int j=index;j>=0;--j) {
+ if(seq[j]==0) {
+ seq[j]=codeset[filled];
+ --filled;
+ break;
+ }
+ }
+ right = true;
+ }
+ }
+ return new Symm(seq,this);
+ }
+}
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