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Diffstat (limited to 'bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/signedcontent/Base64.java')
| -rw-r--r-- | bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/signedcontent/Base64.java | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/signedcontent/Base64.java b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/signedcontent/Base64.java new file mode 100644 index 000000000..32d09834f --- /dev/null +++ b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/signedcontent/Base64.java @@ -0,0 +1,198 @@ +/******************************************************************************* + * Copyright (c) 2006, 2007 IBM Corporation and others. + * All rights reserved. This program and the accompanying materials + * are made available under the terms of the Eclipse Public License v1.0 + * which accompanies this distribution, and is available at + * http://www.eclipse.org/legal/epl-v10.html + * + * Contributors: + * IBM Corporation - initial API and implementation + *******************************************************************************/ +package org.eclipse.osgi.internal.signedcontent; + +public class Base64 { + + private static final byte equalSign = (byte) '='; + + static char digits[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // + 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // + 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // + 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'}; + + /** + * This method decodes the byte array in base 64 encoding into a char array + * Base 64 encoding has to be according to the specification given by the + * RFC 1521 (5.2). + * + * @param data the encoded byte array + * @return the decoded byte array + */ + public static byte[] decode(byte[] data) { + if (data.length == 0) + return data; + int lastRealDataIndex = data.length - 1; + while (data[lastRealDataIndex] == equalSign) + lastRealDataIndex--; + // original data digit is 8 bits long, but base64 digit is 6 bits long + int padBytes = data.length - 1 - lastRealDataIndex; + int byteLength = data.length * 6 / 8 - padBytes; + byte[] result = new byte[byteLength]; + // Each 4 bytes of input (encoded) we end up with 3 bytes of output + int dataIndex = 0; + int resultIndex = 0; + int allBits = 0; + // how many result chunks we can process before getting to pad bytes + int resultChunks = (lastRealDataIndex + 1) / 4; + for (int i = 0; i < resultChunks; i++) { + allBits = 0; + // Loop 4 times gathering input bits (4 * 6 = 24) + for (int j = 0; j < 4; j++) + allBits = (allBits << 6) | decodeDigit(data[dataIndex++]); + // Loop 3 times generating output bits (3 * 8 = 24) + for (int j = resultIndex + 2; j >= resultIndex; j--) { + result[j] = (byte) (allBits & 0xff); // Bottom 8 bits + allBits = allBits >>> 8; + } + resultIndex += 3; // processed 3 result bytes + } + // Now we do the extra bytes in case the original (non-encoded) data + // was not multiple of 3 bytes + switch (padBytes) { + case 1 : + // 1 pad byte means 3 (4-1) extra Base64 bytes of input, 18 + // bits, of which only 16 are meaningful + // Or: 2 bytes of result data + allBits = 0; + // Loop 3 times gathering input bits + for (int j = 0; j < 3; j++) + allBits = (allBits << 6) | decodeDigit(data[dataIndex++]); + // NOTE - The code below ends up being equivalent to allBits = + // allBits>>>2 + // But we code it in a non-optimized way for clarity + // The 4th, missing 6 bits are all 0 + allBits = allBits << 6; + // The 3rd, missing 8 bits are all 0 + allBits = allBits >>> 8; + // Loop 2 times generating output bits + for (int j = resultIndex + 1; j >= resultIndex; j--) { + result[j] = (byte) (allBits & 0xff); // Bottom 8 + // bits + allBits = allBits >>> 8; + } + break; + case 2 : + // 2 pad bytes mean 2 (4-2) extra Base64 bytes of input, 12 bits + // of data, of which only 8 are meaningful + // Or: 1 byte of result data + allBits = 0; + // Loop 2 times gathering input bits + for (int j = 0; j < 2; j++) + allBits = (allBits << 6) | decodeDigit(data[dataIndex++]); + // NOTE - The code below ends up being equivalent to allBits = + // allBits>>>4 + // But we code it in a non-optimized way for clarity + // The 3rd and 4th, missing 6 bits are all 0 + allBits = allBits << 6; + allBits = allBits << 6; + // The 3rd and 4th, missing 8 bits are all 0 + allBits = allBits >>> 8; + allBits = allBits >>> 8; + result[resultIndex] = (byte) (allBits & 0xff); // Bottom + // 8 + // bits + break; + } + return result; + } + + /** + * This method converts a Base 64 digit to its numeric value. + * + * @param data digit (character) to convert + * @return value for the digit + */ + static int decodeDigit(byte data) { + char charData = (char) data; + if (charData <= 'Z' && charData >= 'A') + return charData - 'A'; + if (charData <= 'z' && charData >= 'a') + return charData - 'a' + 26; + if (charData <= '9' && charData >= '0') + return charData - '0' + 52; + switch (charData) { + case '+' : + return 62; + case '/' : + return 63; + default : + throw new IllegalArgumentException("Invalid char to decode: " + data); //$NON-NLS-1$ + } + } + + /** + * This method encodes the byte array into a char array in base 64 according + * to the specification given by the RFC 1521 (5.2). + * + * @param data the encoded char array + * @return the byte array that needs to be encoded + */ + public static byte[] encode(byte[] data) { + int sourceChunks = data.length / 3; + int len = ((data.length + 2) / 3) * 4; + byte[] result = new byte[len]; + int extraBytes = data.length - (sourceChunks * 3); + // Each 4 bytes of input (encoded) we end up with 3 bytes of output + int dataIndex = 0; + int resultIndex = 0; + int allBits = 0; + for (int i = 0; i < sourceChunks; i++) { + allBits = 0; + // Loop 3 times gathering input bits (3 * 8 = 24) + for (int j = 0; j < 3; j++) + allBits = (allBits << 8) | (data[dataIndex++] & 0xff); + // Loop 4 times generating output bits (4 * 6 = 24) + for (int j = resultIndex + 3; j >= resultIndex; j--) { + result[j] = (byte) digits[(allBits & 0x3f)]; // Bottom + // 6 + // bits + allBits = allBits >>> 6; + } + resultIndex += 4; // processed 4 result bytes + } + // Now we do the extra bytes in case the original (non-encoded) data + // is not multiple of 4 bytes + switch (extraBytes) { + case 1 : + allBits = data[dataIndex++]; // actual byte + allBits = allBits << 8; // 8 bits of zeroes + allBits = allBits << 8; // 8 bits of zeroes + // Loop 4 times generating output bits (4 * 6 = 24) + for (int j = resultIndex + 3; j >= resultIndex; j--) { + result[j] = (byte) digits[(allBits & 0x3f)]; // Bottom + // 6 + // bits + allBits = allBits >>> 6; + } + // 2 pad tags + result[result.length - 1] = (byte) '='; + result[result.length - 2] = (byte) '='; + break; + case 2 : + allBits = data[dataIndex++]; // actual byte + allBits = (allBits << 8) | (data[dataIndex++] & 0xff); // actual + // byte + allBits = allBits << 8; // 8 bits of zeroes + // Loop 4 times generating output bits (4 * 6 = 24) + for (int j = resultIndex + 3; j >= resultIndex; j--) { + result[j] = (byte) digits[(allBits & 0x3f)]; // Bottom + // 6 + // bits + allBits = allBits >>> 6; + } + // 1 pad tag + result[result.length - 1] = (byte) '='; + break; + } + return result; + } +} |