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Diffstat (limited to 'src/org/jivesoftware/smack/util/Base32Encoder.java')
| -rw-r--r-- | src/org/jivesoftware/smack/util/Base32Encoder.java | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/src/org/jivesoftware/smack/util/Base32Encoder.java b/src/org/jivesoftware/smack/util/Base32Encoder.java new file mode 100644 index 0000000..0a4ea21 --- /dev/null +++ b/src/org/jivesoftware/smack/util/Base32Encoder.java @@ -0,0 +1,184 @@ +/** + * All rights reserved. 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. + */ +package org.jivesoftware.smack.util; + + +import java.io.ByteArrayOutputStream; +import java.io.DataOutputStream; +import java.io.IOException; + +/** + * Base32 string encoding is useful for when filenames case-insensitive filesystems are encoded. + * Base32 representation takes roughly 20% more space then Base64. + * + * @author Florian Schmaus + * Based on code by Brian Wellington (bwelling@xbill.org) + * @see <a href="http://en.wikipedia.org/wiki/Base32">Base32 Wikipedia entry<a> + * + */ +public class Base32Encoder implements StringEncoder { + + private static Base32Encoder instance = new Base32Encoder(); + private static final String ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ2345678"; + + private Base32Encoder() { + // Use getInstance() + } + + public static Base32Encoder getInstance() { + return instance; + } + + @Override + public String decode(String str) { + ByteArrayOutputStream bs = new ByteArrayOutputStream(); + byte[] raw = str.getBytes(); + for (int i = 0; i < raw.length; i++) { + char c = (char) raw[i]; + if (!Character.isWhitespace(c)) { + c = Character.toUpperCase(c); + bs.write((byte) c); + } + } + + while (bs.size() % 8 != 0) + bs.write('8'); + + byte[] in = bs.toByteArray(); + + bs.reset(); + DataOutputStream ds = new DataOutputStream(bs); + + for (int i = 0; i < in.length / 8; i++) { + short[] s = new short[8]; + int[] t = new int[5]; + + int padlen = 8; + for (int j = 0; j < 8; j++) { + char c = (char) in[i * 8 + j]; + if (c == '8') + break; + s[j] = (short) ALPHABET.indexOf(in[i * 8 + j]); + if (s[j] < 0) + return null; + padlen--; + } + int blocklen = paddingToLen(padlen); + if (blocklen < 0) + return null; + + // all 5 bits of 1st, high 3 (of 5) of 2nd + t[0] = (s[0] << 3) | s[1] >> 2; + // lower 2 of 2nd, all 5 of 3rd, high 1 of 4th + t[1] = ((s[1] & 0x03) << 6) | (s[2] << 1) | (s[3] >> 4); + // lower 4 of 4th, high 4 of 5th + t[2] = ((s[3] & 0x0F) << 4) | ((s[4] >> 1) & 0x0F); + // lower 1 of 5th, all 5 of 6th, high 2 of 7th + t[3] = (s[4] << 7) | (s[5] << 2) | (s[6] >> 3); + // lower 3 of 7th, all of 8th + t[4] = ((s[6] & 0x07) << 5) | s[7]; + + try { + for (int j = 0; j < blocklen; j++) + ds.writeByte((byte) (t[j] & 0xFF)); + } catch (IOException e) { + } + } + + return new String(bs.toByteArray()); + } + + @Override + public String encode(String str) { + byte[] b = str.getBytes(); + ByteArrayOutputStream os = new ByteArrayOutputStream(); + + for (int i = 0; i < (b.length + 4) / 5; i++) { + short s[] = new short[5]; + int t[] = new int[8]; + + int blocklen = 5; + for (int j = 0; j < 5; j++) { + if ((i * 5 + j) < b.length) + s[j] = (short) (b[i * 5 + j] & 0xFF); + else { + s[j] = 0; + blocklen--; + } + } + int padlen = lenToPadding(blocklen); + + // convert the 5 byte block into 8 characters (values 0-31). + + // upper 5 bits from first byte + t[0] = (byte) ((s[0] >> 3) & 0x1F); + // lower 3 bits from 1st byte, upper 2 bits from 2nd. + t[1] = (byte) (((s[0] & 0x07) << 2) | ((s[1] >> 6) & 0x03)); + // bits 5-1 from 2nd. + t[2] = (byte) ((s[1] >> 1) & 0x1F); + // lower 1 bit from 2nd, upper 4 from 3rd + t[3] = (byte) (((s[1] & 0x01) << 4) | ((s[2] >> 4) & 0x0F)); + // lower 4 from 3rd, upper 1 from 4th. + t[4] = (byte) (((s[2] & 0x0F) << 1) | ((s[3] >> 7) & 0x01)); + // bits 6-2 from 4th + t[5] = (byte) ((s[3] >> 2) & 0x1F); + // lower 2 from 4th, upper 3 from 5th; + t[6] = (byte) (((s[3] & 0x03) << 3) | ((s[4] >> 5) & 0x07)); + // lower 5 from 5th; + t[7] = (byte) (s[4] & 0x1F); + + // write out the actual characters. + for (int j = 0; j < t.length - padlen; j++) { + char c = ALPHABET.charAt(t[j]); + os.write(c); + } + } + return new String(os.toByteArray()); + } + + private static int lenToPadding(int blocklen) { + switch (blocklen) { + case 1: + return 6; + case 2: + return 4; + case 3: + return 3; + case 4: + return 1; + case 5: + return 0; + default: + return -1; + } + } + + private static int paddingToLen(int padlen) { + switch (padlen) { + case 6: + return 1; + case 4: + return 2; + case 3: + return 3; + case 1: + return 4; + case 0: + return 5; + default: + return -1; + } + } + +} |