Class Base64

  • All Implemented Interfaces:
    BinaryDecoder, BinaryEncoder, Decoder, Encoder

    public class Base64
    extends BaseNCodec
    Provides Base64 encoding and decoding as defined by RFC 2045.

    This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.

    The class can be parameterized in the following manner with various constructors:

    • URL-safe mode: Default off.
    • Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
    • Line separator: Default is CRLF ("\r\n")

    The URL-safe parameter is only applied to encode operations. Decoding seamlessly handles both modes.

    Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).

    This class is thread-safe.

    Since:
    1.0
    See Also:
    RFC 2045
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static int BITS_PER_ENCODED_BYTE
      BASE32 characters are 6 bits in length.
      private static int BYTES_PER_ENCODED_BLOCK  
      private static int BYTES_PER_UNENCODED_BLOCK  
      private static byte[] DECODE_TABLE
      This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into their 6-bit positive integer equivalents.
      private int decodeSize
      Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      private byte[] decodeTable  
      private int encodeSize
      Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      private byte[] encodeTable
      Encode table to use: either STANDARD or URL_SAFE.
      private byte[] lineSeparator
      Line separator for encoding.
      private static int MASK_2BITS
      Mask used to extract 2 bits, used when decoding final trailing character.
      private static int MASK_4BITS
      Mask used to extract 4 bits, used when decoding final trailing character.
      private static int MASK_6BITS
      Mask used to extract 6 bits, used when encoding
      private static 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 Table 1 of RFC 2045.
      private static 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.
    • Constructor Summary

      Constructors 
      Constructor Description
      Base64()
      Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      Base64​(boolean urlSafe)
      Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
      Base64​(int lineLength)
      Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      Base64​(int lineLength, byte[] lineSeparator)
      Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      Base64​(int lineLength, byte[] lineSeparator, boolean urlSafe)
      Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      Base64​(int lineLength, byte[] lineSeparator, boolean urlSafe, CodecPolicy decodingPolicy)
      Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      (package private) void decode​(byte[] in, int inPos, int inAvail, BaseNCodec.Context context)
      Decodes all of the provided data, starting at inPos, for inAvail bytes.
      static byte[] decodeBase64​(byte[] base64Data)
      Decodes Base64 data into octets.
      static byte[] decodeBase64​(java.lang.String base64String)
      Decodes a Base64 String into octets.
      static java.math.BigInteger decodeInteger​(byte[] pArray)
      Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
      (package private) void encode​(byte[] in, int inPos, int inAvail, BaseNCodec.Context context)
      Encodes all of the provided data, starting at inPos, for inAvail bytes.
      static byte[] encodeBase64​(byte[] binaryData)
      Encodes binary data using the base64 algorithm but does not chunk the output.
      static byte[] encodeBase64​(byte[] binaryData, boolean isChunked)
      Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      static byte[] encodeBase64​(byte[] binaryData, boolean isChunked, boolean urlSafe)
      Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      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.
      static byte[] encodeBase64Chunked​(byte[] binaryData)
      Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
      static java.lang.String encodeBase64String​(byte[] binaryData)
      Encodes binary data using the base64 algorithm but does not chunk the output.
      static byte[] encodeBase64URLSafe​(byte[] binaryData)
      Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output.
      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.
      static byte[] encodeInteger​(java.math.BigInteger bigInteger)
      Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
      static boolean isArrayByteBase64​(byte[] arrayOctet)
      Deprecated.
      1.5 Use isBase64(byte[]), will be removed in 2.0.
      static boolean isBase64​(byte octet)
      Returns whether or not the octet is in the base 64 alphabet.
      static boolean isBase64​(byte[] arrayOctet)
      Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
      static boolean isBase64​(java.lang.String base64)
      Tests a given String to see if it contains only valid characters within the Base64 alphabet.
      protected boolean isInAlphabet​(byte octet)
      Returns whether or not the octet is in the Base64 alphabet.
      boolean isUrlSafe()
      Returns our current encode mode.
      (package private) static byte[] toIntegerBytes​(java.math.BigInteger bigInt)
      Returns a byte-array representation of a BigInteger without sign bit.
      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 base 64 values.
      private void validateTrailingCharacter()
      Validates whether decoding allows an entire final trailing character that cannot be used for a complete byte.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • BITS_PER_ENCODED_BYTE

        private static final int BITS_PER_ENCODED_BYTE
        BASE32 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 Table 1 of RFC 2045. Thanks to "commons" project in ws.apache.org for this code. http://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 Table 1 of RFC 2045) 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. Note: '+' 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. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      • MASK_6BITS

        private static final int MASK_6BITS
        Mask used to extract 6 bits, used when encoding
        See Also:
        Constant Field Values
      • MASK_4BITS

        private static final int MASK_4BITS
        Mask used to extract 4 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values
      • MASK_2BITS

        private static final int MASK_2BITS
        Mask used to extract 2 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values
      • encodeTable

        private final byte[] encodeTable
        Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch between the two modes.
      • decodeTable

        private final byte[] decodeTable
      • lineSeparator

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

        private final int decodeSize
        Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. decodeSize = 3 + lineSeparator.length;
      • 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;
    • Constructor Detail

      • Base64

        public Base64()
        Creates 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

        public Base64​(boolean urlSafe)
        Creates 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

        public Base64​(int lineLength)
        Creates 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 nearest multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        Since:
        1.4
      • Base64

        public Base64​(int lineLength,
                      byte[] lineSeparator)
        Creates 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 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

        public Base64​(int lineLength,
                      byte[] lineSeparator,
                      boolean urlSafe)
        Creates 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 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. Note: 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

        public Base64​(int lineLength,
                      byte[] lineSeparator,
                      boolean urlSafe,
                      CodecPolicy decodingPolicy)
        Creates 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 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. Note: 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

      • decodeBase64

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

        Note: this method seamlessly handles data encoded in URL-safe or normal mode.

        Parameters:
        base64Data - Byte array containing Base64 data
        Returns:
        Array containing decoded data.
      • decodeBase64

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

        Note: this method seamlessly handles data encoded in URL-safe or normal mode.

        Parameters:
        base64String - String containing Base64 data
        Returns:
        Array containing decoded data.
        Since:
        1.4
      • decodeInteger

        public static java.math.BigInteger decodeInteger​(byte[] pArray)
        Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
        Parameters:
        pArray - 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. Note: 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. Note: 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. NOTE: We changed the behavior of this method from multi-line chunking (commons-codec-1.4) to single-line non-chunking (commons-codec-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. Note: 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. Note: 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)
        Returns whether or not the octet is in the base 64 alphabet.
        Parameters:
        octet - The value to test
        Returns:
        true if the value is defined in the the base 64 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.
        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.
        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
      • 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
      • decode

        void decode​(byte[] in,
                    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 (e.g. 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. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/

        Specified by:
        decode in class BaseNCodec
        Parameters:
        in - 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).

        Note: 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. http://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
      • 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 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 base 64 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