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Revert "Revert "SAK-49209 - Avoid double URL encoding - use Base62 fo…
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129 changes: 129 additions & 0 deletions
129
basiclti/tsugi-util/src/java/org/tsugi/util/Base62.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,129 @@ | ||
| /** | ||
| * This class provides utility methods for encoding and decoding data using the Base62 encoding scheme. | ||
| * Base62 is a binary-to-text encoding scheme that represents binary data using a set of 62 alphanumeric characters (A-Z, a-z, and 0-9). | ||
| * It is useful for converting binary data (e.g., byte arrays) into strings that are safe for use in URLs and other text-based contexts. | ||
| */ | ||
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| /* This code was written using the following ChatGPT prompts: | ||
| * | ||
| * Can you write a base62 encoder and decoder in java | ||
| * Could you make this encode and decode strings and not numbers | ||
| * Please complete the implementation details | ||
| * Please write the JavaDoc for this class. | ||
| * Please write a unit test for this class. | ||
| */ | ||
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| package org.tsugi.util; | ||
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| import java.util.HashMap; | ||
| import java.util.Map; | ||
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| public class Base62 { | ||
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| /** | ||
| * The characters used for Base62 encoding. | ||
| */ | ||
| private static final String BASE62_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; | ||
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| /** | ||
| * A mapping of characters to their corresponding index in the Base62 character set. | ||
| */ | ||
| private static final Map<Character, Integer> CHAR_TO_INDEX_MAP = new HashMap<>(); | ||
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| /** | ||
| * Initializes the CHAR_TO_INDEX_MAP with character-to-index mappings for Base62 characters. | ||
| */ | ||
| static { | ||
| for (int i = 0; i < BASE62_CHARS.length(); i++) { | ||
| CHAR_TO_INDEX_MAP.put(BASE62_CHARS.charAt(i), i); | ||
| } | ||
| } | ||
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| /** | ||
| * Encodes a given string into a Base62-encoded string. | ||
| * | ||
| * @param data The input string to be encoded. | ||
| * @return The Base62-encoded string. | ||
| */ | ||
| public static String encode(String data) { | ||
| if ( data == null ) return null; | ||
| byte[] bytes = data.getBytes(); | ||
| StringBuilder encoded = new StringBuilder(); | ||
| long value = 0; | ||
| int bits = 0; | ||
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| for (byte b : bytes) { | ||
| value = (value << 8) | (b & 0xFF); | ||
| bits += 8; | ||
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| while (bits >= 6) { | ||
| int index = (int) ((value >> (bits - 6)) & 0x3F); | ||
| encoded.append(BASE62_CHARS.charAt(index)); | ||
| bits -= 6; | ||
| } | ||
| } | ||
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| if (bits > 0) { | ||
| int index = (int) ((value << (6 - bits)) & 0x3F); | ||
| encoded.append(BASE62_CHARS.charAt(index)); | ||
| } | ||
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| return encoded.toString(); | ||
| } | ||
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| /** | ||
| * Decodes a Base62-encoded string into its original string representation. | ||
| * | ||
| * @param base62 The Base62-encoded string to be decoded. | ||
| * @return The decoded original string. | ||
| * @throws IllegalArgumentException If the input string contains invalid Base62 characters. | ||
| */ | ||
| public static String decode(String base62) throws IllegalArgumentException { | ||
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| if ( base62 == null ) return null; | ||
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| long value = 0; | ||
| int bits = 0; | ||
| byte[] bytes = new byte[base62.length() * 6 / 8]; | ||
| int byteIndex = 0; | ||
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| for (int i = 0; i < base62.length(); i++) { | ||
| char c = base62.charAt(i); | ||
| int charValue = CHAR_TO_INDEX_MAP.getOrDefault(c, -1); | ||
| if (charValue == -1) { | ||
| throw new IllegalArgumentException("Invalid character in base62 string: " + c); | ||
| } | ||
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| value = (value << 6) | charValue; | ||
| bits += 6; | ||
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| while (bits >= 8) { | ||
| bytes[byteIndex++] = (byte) ((value >> (bits - 8)) & 0xFF); | ||
| bits -= 8; | ||
| } | ||
| } | ||
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| return new String(bytes, 0, byteIndex); | ||
| } | ||
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| /** | ||
| * Decodes a Base62-encoded string into its original string representation or returning the original string | ||
| * | ||
| * This is a way to easily recover from a double decode. This is a little soft in its approach | ||
| * and only works if the strings being encoded and decoded have non-base62 characters. | ||
| * | ||
| * @param base62 The Base62-encoded string to be decoded. | ||
| * @return The decoded original string or the original string if the input string is not Base62 | ||
| */ | ||
| public static String decodeSafe(String base62) throws IllegalArgumentException { | ||
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| if ( base62 == null ) return null; | ||
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| try { | ||
| return decode(base62); | ||
| } catch (IllegalArgumentException e) { | ||
| return base62; | ||
| } | ||
| } | ||
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| } |
142 changes: 142 additions & 0 deletions
142
basiclti/tsugi-util/src/test/org/tsugi/util/Base62Test.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,142 @@ | ||
| package org.tsugi.util; | ||
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| import static org.junit.Assert.assertEquals; | ||
| import static org.junit.Assert.fail; | ||
| import static org.junit.Assert.assertFalse; | ||
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| import org.junit.Test; | ||
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| import org.tsugi.util.Base62; | ||
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| /* This code was written by ChatGPT with the following prompt | ||
| * Please write a unit test for a Base62 class | ||
| */ | ||
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| public class Base62Test { | ||
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| @Test | ||
| public void testEncodeAndDecode() { | ||
| String[] testStrings = { | ||
| "Hello, Base62!", | ||
| "Testing encoding and decoding.", | ||
| "12345", | ||
| "This is a longer string with more characters.", | ||
| "A tree 🌲 was here", | ||
| "A", | ||
| "" | ||
| }; | ||
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| for (String input : testStrings) { | ||
| String encoded = Base62.encode(input); | ||
| String decoded = Base62.decode(encoded); | ||
| assertEquals("Decoding did not produce the original string for input: " + input, input, decoded); | ||
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| try { | ||
| String urlEncoded = java.net.URLEncoder.encode(encoded, "UTF-8"); | ||
| assertEquals("UrlEncoding changed the string: " + encoded, encoded, urlEncoded); | ||
| } catch (java.io.UnsupportedEncodingException e) { | ||
| fail("Unxpected UnsupportedEncodingException for URLEncoder "+encoded); | ||
| } | ||
| } | ||
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| assertEquals("Encode of null should produce null: ", null, Base62.encode(null)); | ||
| assertEquals("Decode of null should produce null: ", null, Base62.decode(null)); | ||
| } | ||
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| @Test | ||
| public void testInvalidCharacters() { | ||
| // Test invalid characters in decoding | ||
| String invalidBase62String = "InvalidString$#@!"; | ||
| try { | ||
| Base62.decode(invalidBase62String); | ||
| fail("Expected IllegalArgumentException for invalid Base62 string"); | ||
| } catch (IllegalArgumentException e) { | ||
| // Expected exception | ||
| } | ||
| assertEquals("Encode of null should produce null: ", null, Base62.encode(null)); | ||
| } | ||
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| @Test | ||
| public void testInvalidCharactersSafe() { | ||
| // Test invalid characters in decoding | ||
| String invalidBase62String = "InvalidString$#@!"; | ||
| String decoded = Base62.decodeSafe(invalidBase62String); | ||
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| assertEquals("Safe decode of non-base22 string should return the string: ", invalidBase62String, decoded); | ||
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| String encoded = Base62.encode(invalidBase62String); | ||
| decoded = Base62.decodeSafe(encoded); | ||
| assertEquals("Safe decode of base22 string should return the decoded string: ", invalidBase62String, decoded); | ||
| } | ||
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| /** | ||
| * As is always the case, developers resist the idea of using Base62 with things like | ||
| * Base64 URL safe encoding. Which as the example below shows that whilst the resulting | ||
| * encoded strings *are* URL Encodable - they will suffer when double URL encoding happens. | ||
| */ | ||
| @Test | ||
| public void testVerifyJavaBase64UrlSafeEncodingFails() throws Exception { | ||
| String[] testStrings = { | ||
| "Hello, World!", | ||
| "12345", | ||
| "abcABC", | ||
| "A tree 🌲 was here", | ||
| "!@#$%^&*()_+{}[]|\\:;<>,.?/~`" | ||
| }; | ||
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| int failcount = 0; | ||
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| for (String input : testStrings) { | ||
| String base64UrlEncoded = java.util.Base64.getUrlEncoder().encodeToString(input.getBytes("UTF-8")); | ||
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| // URL-encode the base64 URL encoded string | ||
| String urlEncoded = java.net.URLEncoder.encode(base64UrlEncoded, "UTF-8"); | ||
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| // Compare the original encoded string with the URL-encoded string | ||
| if ( ! base64UrlEncoded.equals(urlEncoded)) failcount ++; | ||
| } | ||
| assertFalse(failcount == 0); | ||
| } | ||
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| /** | ||
| * Also suggested in code review was the serialization used by io.jsonwebtoken.io.Base64 | ||
| * which does not pad. But the writers of said code made it private on purpose - probably | ||
| * because it is not precisely Base64 because the lack of padding. | ||
| * | ||
| * This test might work if it were not for the fact that io.jsonwebtoken.io.Base64 is | ||
| * explicitly not public by its creators. Adding this import above will fail to compile: | ||
| * | ||
| * import io.jsonwebtoken.io.Base64; | ||
| * | ||
| * [ERROR] Base62Test.java:[10,25] error: Base64 is not public in io.jsonwebtoken.io; cannot be accessed from outside package | ||
| * | ||
| * The test below might work if it were not for the fact that io.jsonwebtoken.io.Base64 is | ||
| * explicitly not public by its creators. Adding this import above will fail to compile: | ||
| */ | ||
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| /* | ||
| @Test | ||
| public void testIoJsonWebTokenBase64UrlIsPrivate() throws Exception { | ||
| String[] testStrings = { | ||
| "Hello, World!", | ||
| "12345", | ||
| "abcABC", | ||
| "A tree 🌲 was here", | ||
| "!@#$%^&*()_+{}[]|\\:;<>,.?/~`" | ||
| }; | ||
| for (String input : testStrings) { | ||
| // Encode using jjwt-api base64 URL encoding | ||
| boolean linesep = false; | ||
| String base64UrlEncoded = io.jsonwebtoken.io.Base64.URL_SAFE.encodeToString(input.getBytes("UTF-8"), linesep); | ||
| // URL-encode the base64 URL encoded string | ||
| String urlEncoded = java.net.URLEncoder.encode(base64UrlEncoded, "UTF-8"); | ||
| // Compare the original encoded string with the URL-encoded string | ||
| assertEquals(base64UrlEncoded, urlEncoded); | ||
| } | ||
| } | ||
| */ | ||
| } | ||
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