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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8. Note: this package includes the NTRU encryption algorithms.

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package org.bouncycastle.util.encoders;

/**
 * Utilities for working with UTF-8 encodings.
 * 

* Decoding of UTF-8 is based on a presentation by Bob Steagall at CppCon2018 (see * https://github.com/BobSteagall/CppCon2018). It uses a Deterministic Finite Automaton (DFA) to * recognize and decode multi-byte code points. */ public class UTF8 { // Constants for the categorization of code units private static final byte C_ILL = 0; //- C0..C1, F5..FF ILLEGAL octets that should never appear in a UTF-8 sequence private static final byte C_CR1 = 1; //- 80..8F Continuation range 1 private static final byte C_CR2 = 2; //- 90..9F Continuation range 2 private static final byte C_CR3 = 3; //- A0..BF Continuation range 3 private static final byte C_L2A = 4; //- C2..DF Leading byte range A / 2-byte sequence private static final byte C_L3A = 5; //- E0 Leading byte range A / 3-byte sequence private static final byte C_L3B = 6; //- E1..EC, EE..EF Leading byte range B / 3-byte sequence private static final byte C_L3C = 7; //- ED Leading byte range C / 3-byte sequence private static final byte C_L4A = 8; //- F0 Leading byte range A / 4-byte sequence private static final byte C_L4B = 9; //- F1..F3 Leading byte range B / 4-byte sequence private static final byte C_L4C = 10; //- F4 Leading byte range C / 4-byte sequence // private static final byte C_ASC = 11; //- 00..7F ASCII leading byte range // Constants for the states of a DFA private static final byte S_ERR = -2; //- Error state private static final byte S_END = -1; //- End (or Accept) state private static final byte S_CS1 = 0x00; //- Continuation state 1 private static final byte S_CS2 = 0x10; //- Continuation state 2 private static final byte S_CS3 = 0x20; //- Continuation state 3 private static final byte S_P3A = 0x30; //- Partial 3-byte sequence state A private static final byte S_P3B = 0x40; //- Partial 3-byte sequence state B private static final byte S_P4A = 0x50; //- Partial 4-byte sequence state A private static final byte S_P4B = 0x60; //- Partial 4-byte sequence state B private static final short[] firstUnitTable = new short[128]; private static final byte[] transitionTable = new byte[S_P4B + 16]; private static void fill(byte[] table, int first, int last, byte b) { for (int i = first; i <= last; ++i) { table[i] = b; } } static { byte[] categories = new byte[128]; fill(categories, 0x00, 0x0F, C_CR1); fill(categories, 0x10, 0x1F, C_CR2); fill(categories, 0x20, 0x3F, C_CR3); fill(categories, 0x40, 0x41, C_ILL); fill(categories, 0x42, 0x5F, C_L2A); fill(categories, 0x60, 0x60, C_L3A); fill(categories, 0x61, 0x6C, C_L3B); fill(categories, 0x6D, 0x6D, C_L3C); fill(categories, 0x6E, 0x6F, C_L3B); fill(categories, 0x70, 0x70, C_L4A); fill(categories, 0x71, 0x73, C_L4B); fill(categories, 0x74, 0x74, C_L4C); fill(categories, 0x75, 0x7F, C_ILL); fill(transitionTable, 0, transitionTable.length - 1, S_ERR); fill(transitionTable, S_CS1 + 0x8, S_CS1 + 0xB, S_END); fill(transitionTable, S_CS2 + 0x8, S_CS2 + 0xB, S_CS1); fill(transitionTable, S_CS3 + 0x8, S_CS3 + 0xB, S_CS2); fill(transitionTable, S_P3A + 0xA, S_P3A + 0xB, S_CS1); fill(transitionTable, S_P3B + 0x8, S_P3B + 0x9, S_CS1); fill(transitionTable, S_P4A + 0x9, S_P4A + 0xB, S_CS2); fill(transitionTable, S_P4B + 0x8, S_P4B + 0x8, S_CS2); byte[] firstUnitMasks = {0x00, 0x00, 0x00, 0x00, 0x1F, 0x0F, 0x0F, 0x0F, 0x07, 0x07, 0x07}; byte[] firstUnitTransitions = {S_ERR, S_ERR, S_ERR, S_ERR, S_CS1, S_P3A, S_CS2, S_P3B, S_P4A, S_CS3, S_P4B}; for (int i = 0x00; i < 0x80; ++i) { byte category = categories[i]; int codePoint = i & firstUnitMasks[category]; byte state = firstUnitTransitions[category]; firstUnitTable[i] = (short)((codePoint << 8) | state); } } /** * Transcode a UTF-8 encoding into a UTF-16 representation. In the general case the output * {@code utf16} array should be at least as long as the input {@code utf8} one to handle * arbitrary inputs. The number of output UTF-16 code units is returned, or -1 if any errors are * encountered (in which case an arbitrary amount of data may have been written into the output * array). Errors that will be detected are malformed UTF-8, including incomplete, truncated or * "overlong" encodings, and unmappable code points. In particular, no unmatched surrogates will * be produced. An error will also result if {@code utf16} is found to be too small to store the * complete output. * * @param utf8 A non-null array containing a well-formed UTF-8 encoding. * @param utf16 A non-null array, at least as long as the {@code utf8} array in order to ensure * the output will fit. * @return The number of UTF-16 code units written to {@code utf16} (beginning from index 0), or * else -1 if the input was either malformed or encoded any unmappable characters, or if * the {@code utf16} is too small. */ public static int transcodeToUTF16(byte[] utf8, char[] utf16) { int i = 0, j = 0; while (i < utf8.length) { byte codeUnit = utf8[i++]; if (codeUnit >= 0) { if (j >= utf16.length) { return -1; } utf16[j++] = (char)codeUnit; continue; } short first = firstUnitTable[codeUnit & 0x7F]; int codePoint = first >>> 8; byte state = (byte)first; while (state >= 0) { if (i >= utf8.length) { return -1; } codeUnit = utf8[i++]; codePoint = (codePoint << 6) | (codeUnit & 0x3F); state = transitionTable[state + ((codeUnit & 0xFF) >>> 4)]; } if (state == S_ERR) { return -1; } if (codePoint <= 0xFFFF) { if (j >= utf16.length) { return -1; } // Code points from U+D800 to U+DFFF are caught by the DFA utf16[j++] = (char)codePoint; } else { if (j >= utf16.length - 1) { return -1; } // Code points above U+10FFFF are caught by the DFA utf16[j++] = (char)(0xD7C0 + (codePoint >>> 10)); utf16[j++] = (char)(0xDC00 | (codePoint & 0x3FF)); } } return j; } }





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