Package org.apache.commons.codec.binary

Class Base64

    • Field Detail

      • BITS_PER_ENCODED_BYTE

        private static final int BITS_PER_ENCODED_BYTE
        BASE64 characters are 6 bits in length. They are formed by taking a block of 3 octets to form a 24-bit string, which is converted into 4 BASE64 characters.
        See Also:
        Constant Field Values

      • BYTES_PER_UNENCODED_BLOCK

        private static final int BYTES_PER_UNENCODED_BLOCK
        See Also:
        Constant Field Values

      • BYTES_PER_ENCODED_BLOCK

        private static final int BYTES_PER_ENCODED_BLOCK
        See Also:
        Constant Field Values

      • STANDARD_ENCODE_TABLE

        private static final byte[] STANDARD_ENCODE_TABLE
        This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet" equivalents as specified in RFC 2045 Table 1: The Base64 Alphabet.

        Thanks to "commons" project in ws.apache.org for this code. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/

      • URL_SAFE_ENCODE_TABLE

        private static final byte[] URL_SAFE_ENCODE_TABLE
        This is a copy of the STANDARD_ENCODE_TABLE above, but with + and / changed to - and _ to make the encoded Base64 results more URL-SAFE. This table is only used when the Base64's mode is set to URL-SAFE.

      • DECODE_TABLE

        private static final byte[] DECODE_TABLE
        This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in RFC 2045 Table 1: The Base64 Alphabet) into their 6-bit positive integer equivalents. Characters that are not in the Base64 or Base64 URL-safe alphabets but fall within the bounds of the array are translated to -1.

        The characters '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).

        Thanks to "commons" project in ws.apache.org for this code. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/

      • STANDARD_DECODE_TABLE

        private static final byte[] STANDARD_DECODE_TABLE
        This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in RFC 2045 Table 1: The Base64 Alphabet) into their 6-bit positive integer equivalents. Characters that are not in the Base64 alphabet but fall within the bounds of the array are translated to -1. This decoding table handles only the standard base64 characters, such as '+' and '/'. The "url-safe" characters such as '-' and '_' are not supported by the table.

      • URL_SAFE_DECODE_TABLE

        private static final byte[] URL_SAFE_DECODE_TABLE
        This array is a lookup table that translates Unicode characters drawn from the "Base64 URL-safe Alphabet" (as specified in RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet) into their 6-bit positive integer equivalents. Characters that are not in the Base64 URL-safe alphabet but fall within the bounds of the array are translated to -1. This decoding table handles only the URL-safe base64 characters, such as '-' and '_'. The standard characters such as '+' and '/' are not supported by the table.

      • MASK_6_BITS

        private static final int MASK_6_BITS
        Mask used to extract 6 bits, used when encoding
        See Also:
        Constant Field Values

      • MASK_4_BITS

        private static final int MASK_4_BITS
        Mask used to extract 4 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • MASK_2_BITS

        private static final int MASK_2_BITS
        Mask used to extract 2 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • lineSeparator

        private final byte[] lineSeparator
        Line separator for encoding. Not used when decoding. Only used if lineLength > 0.

      • encodeSize

        private final int encodeSize
        Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. encodeSize = 4 + lineSeparator.length;

      • isUrlSafe

        private final boolean isUrlSafe

      • isStandardEncodeTable

        private final boolean isStandardEncodeTable

    • Constructor Detail

      • Base64

        public Base64()
        Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.

        When encoding the line length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.

        When decoding all variants are supported.

      • Base64

        @Deprecated
public Base64​(boolean urlSafe)
        Deprecated.
        Use builder() and Base64.Builder.
        Constructs a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.

        When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.

        When decoding all variants are supported.

        Parameters:
        urlSafe - if true, URL-safe encoding is used. In most cases this should be set to false.
        Since:
        1.4

      • Base64

        @Deprecated
public Base64​(int lineLength)
        Deprecated.
        Use builder() and Base64.Builder.
        Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.

        When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.

        Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.

        When decoding all variants are supported.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        Since:
        1.4

      • Base64

        @Deprecated
public Base64​(int lineLength,
              byte[] lineSeparator)
        Deprecated.
        Use builder() and Base64.Builder.
        Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.

        When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.

        Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.

        When decoding all variants are supported.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the provided lineSeparator included some base64 characters.
        Since:
        1.4

      • Base64

        @Deprecated
public Base64​(int lineLength,
              byte[] lineSeparator,
              boolean urlSafe)
        Deprecated.
        Use builder() and Base64.Builder.
        Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.

        When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.

        Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.

        When decoding all variants are supported.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        urlSafe - Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode operations. Decoding seamlessly handles both modes. No padding is added when using the URL-safe alphabet.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base64 characters.
        Since:
        1.4

      • Base64

        @Deprecated
public Base64​(int lineLength,
              byte[] lineSeparator,
              boolean urlSafe,
              CodecPolicy decodingPolicy)
        Deprecated.
        Use builder() and Base64.Builder.
        Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.

        When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.

        Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.

        When decoding all variants are supported.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        urlSafe - Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode operations. Decoding seamlessly handles both modes. No padding is added when using the URL-safe alphabet.
        decodingPolicy - The decoding policy.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base64 characters.
        Since:
        1.15

    • Method Detail

      • builder

        public static Base64.Builder builder()
        Creates a new Builder.

        To configure a new instance, use a Base64.Builder. For example: 

         Base64 base64 = Base64.builder()
   .setDecodingPolicy(CodecPolicy.LENIENT) // default is lenient, null resets to default
   .setEncodeTable(customEncodeTable)         // default is built in, null resets to default
   .setLineLength(0)                          // default is none
   .setLineSeparator('\r', '\n')              // default is CR LF, null resets to default
   .setPadding('=')                           // default is '='
   .setUrlSafe(false)                         // default is false
   .get()
        Returns:
        a new Builder.
        Since:
        1.17.0

      • calculateDecodeTable

        private static byte[] calculateDecodeTable​(byte[] encodeTable)
        Calculates a decode table for a given encode table.
        Parameters:
        encodeTable - that is used to determine decode lookup table.
        Returns:
        A new decode table.

      • decodeBase64

        public static byte[] decodeBase64​(byte[] base64Data)
        Decodes Base64 data into octets.

        This method seamlessly handles data encoded in URL-safe or normal mode. For enforcing verification against strict standard Base64 or Base64 URL-safe tables, please use decodeBase64Standard(byte[]) or decodeBase64UrlSafe(byte[]) methods respectively. This method skips unknown or unsupported bytes.

        Parameters:
        base64Data - Byte array containing Base64 data.
        Returns:
        New array containing decoded data.

      • decodeBase64

        public static byte[] decodeBase64​(java.lang.String base64String)
        Decodes a Base64 String into octets.

        This method seamlessly handles data encoded in URL-safe or normal mode. For enforcing verification against strict standard Base64 or Base64 URL-safe tables, please use decodeBase64Standard(String) or decodeBase64UrlSafe(String) methods respectively. This method skips unknown or unsupported bytes.

        Parameters:
        base64String - String containing Base64 data.
        Returns:
        New array containing decoded data.
        Since:
        1.4

      • decodeBase64Standard

        public static byte[] decodeBase64Standard​(byte[] base64Data)
        Decodes standard Base64 data into octets.

        This implementation is aligned with the RFC 2045 Table 1: The Base64 Alphabet. This method skips unknown or unsupported bytes.

        Parameters:
        base64Data - Byte array containing Base64 data.
        Returns:
        New array containing decoded data.
        Since:
        1.21

      • decodeBase64Standard

        public static byte[] decodeBase64Standard​(java.lang.String base64String)
        Decodes a standard Base64 String into octets.

        This implementation is aligned with the RFC 2045 Table 1: The Base64 Alphabet. This method skips unknown or unsupported characters.

        Parameters:
        base64String - String containing Base64 data.
        Returns:
        New array containing decoded data.
        Since:
        1.21

      • decodeBase64UrlSafe

        public static byte[] decodeBase64UrlSafe​(byte[] base64Data)
        Decodes URL-safe Base64 data into octets.

        This implementation is aligned with RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet. This method skips unknown or unsupported characters.

        Parameters:
        base64Data - Byte array containing Base64 data.
        Returns:
        New array containing decoded data.
        Since:
        1.21

      • decodeBase64UrlSafe

        public static byte[] decodeBase64UrlSafe​(java.lang.String base64String)
        Decodes a URL-safe Base64 String into octets.

        This implementation is aligned with RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet. This method skips unknown or unsupported characters.

        Parameters:
        base64String - String containing Base64 data.
        Returns:
        New array containing decoded data.
        Since:
        1.21

      • decodeInteger

        public static java.math.BigInteger decodeInteger​(byte[] array)
        Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
        Parameters:
        array - a byte array containing base64 character data.
        Returns:
        A BigInteger.
        Since:
        1.4

      • encodeBase64

        public static byte[] encodeBase64​(byte[] binaryData)
        Encodes binary data using the base64 algorithm but does not chunk the output.
        Parameters:
        binaryData - binary data to encode.
        Returns:
        byte[] containing Base64 characters in their UTF-8 representation.

      • encodeBase64

        public static byte[] encodeBase64​(byte[] binaryData,
                                  boolean isChunked)
        Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
        Parameters:
        binaryData - Array containing binary data to encode.
        isChunked - if true this encoder will chunk the base64 output into 76 character blocks.
        Returns:
        Base64-encoded data.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the input array needs an output array bigger than Integer.MAX_VALUE.

      • encodeBase64

        public static byte[] encodeBase64​(byte[] binaryData,
                                  boolean isChunked,
                                  boolean urlSafe)
        Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
        Parameters:
        binaryData - Array containing binary data to encode.
        isChunked - if true this encoder will chunk the base64 output into 76 character blocks.
        urlSafe - if true this encoder will emit - and _ instead of the usual + and / characters. No padding is added when encoding using the URL-safe alphabet.
        Returns:
        Base64-encoded data.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the input array needs an output array bigger than Integer.MAX_VALUE.
        Since:
        1.4

      • encodeBase64

        public static byte[] encodeBase64​(byte[] binaryData,
                                  boolean isChunked,
                                  boolean urlSafe,
                                  int maxResultSize)
        Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
        Parameters:
        binaryData - Array containing binary data to encode.
        isChunked - if true this encoder will chunk the base64 output into 76 character blocks.
        urlSafe - if true this encoder will emit - and _ instead of the usual + and / characters. No padding is added when encoding using the URL-safe alphabet.
        maxResultSize - The maximum result size to accept.
        Returns:
        Base64-encoded data.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the input array needs an output array bigger than maxResultSize.
        Since:
        1.4

      • encodeBase64Chunked

        public static byte[] encodeBase64Chunked​(byte[] binaryData)
        Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
        Parameters:
        binaryData - binary data to encode.
        Returns:
        Base64 characters chunked in 76 character blocks.

      • encodeBase64String

        public static java.lang.String encodeBase64String​(byte[] binaryData)
        Encodes binary data using the base64 algorithm but does not chunk the output.

        We changed the behavior of this method from multi-line chunking (1.4) to single-line non-chunking (1.5).

        Parameters:
        binaryData - binary data to encode.
        Returns:
        String containing Base64 characters.
        Since:
        1.4 (NOTE: 1.4 chunked the output, whereas 1.5 does not).

      • encodeBase64URLSafe

        public static byte[] encodeBase64URLSafe​(byte[] binaryData)
        Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of + and / characters. No padding is added.
        Parameters:
        binaryData - binary data to encode.
        Returns:
        byte[] containing Base64 characters in their UTF-8 representation.
        Since:
        1.4

      • encodeBase64URLSafeString

        public static java.lang.String encodeBase64URLSafeString​(byte[] binaryData)
        Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of + and / characters. No padding is added.
        Parameters:
        binaryData - binary data to encode.
        Returns:
        String containing Base64 characters.
        Since:
        1.4

      • encodeInteger

        public static byte[] encodeInteger​(java.math.BigInteger bigInteger)
        Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
        Parameters:
        bigInteger - a BigInteger.
        Returns:
        A byte array containing base64 character data.
        Throws:
        java.lang.NullPointerException - if null is passed in.
        Since:
        1.4

      • isArrayByteBase64

        @Deprecated
public static boolean isArrayByteBase64​(byte[] arrayOctet)
        Deprecated.
        1.5 Use isBase64(byte[]), will be removed in 2.0.
        Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.
        Parameters:
        arrayOctet - byte array to test.
        Returns:
        true if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; false, otherwise.

      • isBase64

        public static boolean isBase64​(byte octet)
        Tests whether or not the octet is in the Base64 alphabet.

        This method threats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/' (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe tables, please use isBase64Standard(byte) or isBase64Url(byte) methods respectively.

        Parameters:
        octet - The value to test.
        Returns:
        true if the value is defined in the Base64 alphabet, false otherwise.
        Since:
        1.4

      • isBase64

        public static boolean isBase64​(byte[] arrayOctet)
        Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.

        This method treats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/' (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe tables, please use isBase64Standard(byte[]) or isBase64Url(byte[]) methods respectively.

        Parameters:
        arrayOctet - byte array to test.
        Returns:
        true if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; false, otherwise.
        Since:
        1.5

      • isBase64

        public static boolean isBase64​(java.lang.String base64)
        Tests a given String to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.

        This method threats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/' (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe tables, please use isBase64Standard(String) or isBase64Url(String) methods respectively.

        Parameters:
        base64 - String to test.
        Returns:
        true if all characters in the String are valid characters in the Base64 alphabet or if the String is empty; false, otherwise.
        Since:
        1.5

      • isBase64Standard

        public static boolean isBase64Standard​(byte octet)
        Tests whether or not the octet is in the standard Base64 alphabet.

        This implementation is aligned with RFC 2045 Table 1: The Base64 Alphabet.

        Parameters:
        octet - The value to test.
        Returns:
        true if the value is defined in the standard Base64 alphabet, false otherwise.
        Since:
        1.21

      • isBase64Standard

        public static boolean isBase64Standard​(byte[] arrayOctet)
        Tests a given byte array to see if it contains only valid characters within the standard Base64 alphabet. The method treats whitespace as valid.

        This implementation is aligned with RFC 2045 Table 1: The Base64 Alphabet.

        Parameters:
        arrayOctet - byte array to test.
        Returns:
        true if all bytes are valid characters in the standard Base64 alphabet. false, otherwise.
        Since:
        1.21

      • isBase64Standard

        public static boolean isBase64Standard​(java.lang.String base64)
        Tests a given String to see if it contains only valid characters within the standard Base64 alphabet. The method treats whitespace as valid.

        This implementation is aligned with RFC 2045 Table 1: The Base64 Alphabet.

        Parameters:
        base64 - String to test.
        Returns:
        true if all characters in the String are valid characters in the standard Base64 alphabet or if the String is empty; false, otherwise.
        Since:
        1.21

      • isBase64Url

        public static boolean isBase64Url​(byte octet)
        Tests whether or not the octet is in the URL-safe Base64 alphabet.

        This implementation is aligned with RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet.

        Parameters:
        octet - The value to test.
        Returns:
        true if the value is defined in the URL-safe Base64 alphabet, false otherwise.
        Since:
        1.21

      • isBase64Url

        public static boolean isBase64Url​(byte[] arrayOctet)
        Tests a given byte array to see if it contains only valid characters within the URL-safe Base64 alphabet. The method treats whitespace as valid.

        This implementation is aligned with RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet.

        Parameters:
        arrayOctet - byte array to test.
        Returns:
        true if all bytes are valid characters in the URL-safe Base64 alphabet, false, otherwise.
        Since:
        1.21

      • isBase64Url

        public static boolean isBase64Url​(java.lang.String base64)
        Tests a given String to see if it contains only valid characters within the URL-safe Base64 alphabet. The method treats whitespace as valid.

        This implementation is aligned with RFC 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet.

        Parameters:
        base64 - String to test.
        Returns:
        true if all characters in the String are valid characters in the URL-safe Base64 alphabet or if the String is empty; false, otherwise.
        Since:
        1.21

      • toIntegerBytes

        static byte[] toIntegerBytes​(java.math.BigInteger bigInt)
        Returns a byte-array representation of a BigInteger without sign bit.
        Parameters:
        bigInt - BigInteger to be converted.
        Returns:
        a byte array representation of the BigInteger parameter.

      • toUrlSafeEncodeTable

        static byte[] toUrlSafeEncodeTable​(boolean urlSafe)

      • decode

        void decode​(byte[] input,
            int inPos,
            int inAvail,
            BaseNCodec.Context context)

        Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.

        Ignores all non-base64 characters. This is how chunked (for example 76 character) data is handled, since CR and LF are silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.

        Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/

        Specified by:
        decode in class BaseNCodec
        Parameters:
        input - byte[] array of ASCII data to base64 decode.
        inPos - Position to start reading data from.
        inAvail - Amount of bytes available from input for decoding.
        context - the context to be used.

      • encode

        void encode​(byte[] in,
            int inPos,
            int inAvail,
            BaseNCodec.Context context)

        Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, to flush last remaining bytes (if not multiple of 3).

        No padding is added when encoding using the URL-safe alphabet.

        Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/

        Specified by:
        encode in class BaseNCodec
        Parameters:
        in - byte[] array of binary data to base64 encode.
        inPos - Position to start reading data from.
        inAvail - Amount of bytes available from input for encoding.
        context - the context to be used.

      • getLineSeparator

        byte[] getLineSeparator()
        Gets the line separator (for testing only).
        Returns:
        the line separator.

      • isInAlphabet

        protected boolean isInAlphabet​(byte octet)
        Returns whether or not the octet is in the Base64 alphabet.
        Specified by:
        isInAlphabet in class BaseNCodec
        Parameters:
        octet - The value to test.
        Returns:
        true if the value is defined in the Base64 alphabet false otherwise.

      • isUrlSafe

        public boolean isUrlSafe()
        Returns our current encode mode. True if we're URL-safe, false otherwise.
        Returns:
        true if we're in URL-safe mode, false otherwise.
        Since:
        1.4

      • validateCharacter

        private void validateCharacter​(int emptyBitsMask,
                               BaseNCodec.Context context)
        Validates whether decoding the final trailing character is possible in the context of the set of possible Base64 values.

        The character is valid if the lower bits within the provided mask are zero. This is used to test the final trailing base-64 digit is zero in the bits that will be discarded.

        Parameters:
        emptyBitsMask - The mask of the lower bits that should be empty.
        context - the context to be used.
        Throws:
        java.lang.IllegalArgumentException - if the bits being checked contain any non-zero value.

      • validateTrailingCharacter

        private void validateTrailingCharacter()
        Validates whether decoding allows an entire final trailing character that cannot be used for a complete byte.
        Throws:
        java.lang.IllegalArgumentException - if strict decoding is enabled.