NAME

base64 - Provides base64 encode and decode, see
RFC 2045.

DESCRIPTION

Provides base64 encode and decode, see RFC 2045.

DATA TYPES

base64_alphabet() = 


    65..90 | 97..122 | 48..57 | 43 | 47 | 45 | 95 | 61

Base 64 Encoding alphabet, see RFC 4648.

base64_mode() = standard | urlsafe

Selector for the Base 64 Encoding alphabet used for encoding and decoding. See RFC 4648 Sections 4 and 5.

options() = #{padding => boolean(), mode => base64_mode()}

Customises the behaviour of the encode and decode functions. Default value if omitted entirely or partially is #{mode => standard, padding => true}.

base64_string() = [base64_alphabet()]

Base 64 encoded string.

base64_binary() = binary()

Base 64 encoded binary.

byte_string() = [byte()]

Arbitrary sequences of octets.

EXPORTS


decode(Base64) -> Data


decode_to_string(Base64) -> DataString


mime_decode(Base64) -> Data


mime_decode_to_string(Base64) -> DataString

Types:

Base64 = base64_string() | base64_binary()
Data = binary()
DataString = byte_string()

Decodes a base64 string encoded using the standard alphabet according to RFC 4648 Section 4 to plain ASCII.

mime_decode/1 and mime_decode_to_string/1 strip away illegal characters, while decode/1 and decode_to_string/1 only strip away whitespace characters.

Checks the correct number of = padding characters at the end of the encoded string.


decode(Base64, Options) -> Data


decode_to_string(Base64, Options) -> DataString


mime_decode(Base64, Options) -> Data


mime_decode_to_string(Base64, Options) -> DataString

Types:

Base64 = base64_string() | base64_binary()
Options = options()
Data = binary()
DataString = byte_string()

Decodes a base64 string encoded using the alphabet indicated by the mode option to plain ASCII.

mime_decode/2 and mime_decode_to_string/2 strip away illegal characters, while decode/2 and decode_to_string/2 only strip away whitespace characters.

The mode option can be one of the following:

standard:: Default. Decode the given string using the standard base64 alphabet according to RFC 4648 Section 4, that is "+" and "/" are representing bytes 62 and 63 respectively, while "-" and "_" are illegal characters.
urlsafe:: Decode the given string using the alternative "URL and Filename safe" base64 alphabet according to RFC 4648 Section 5, that is "-" and "_" are representing bytes 62 and 63 respectively, while "+" and "/" are illegal characters.

The padding option can be one of the following:

true:: Default. Checks the correct number of = padding characters at the end of the encoded string.
false:: Accepts an encoded string with missing = padding characters at the end.


encode(Data) -> Base64


encode_to_string(Data) -> Base64String

Types:

Data = byte_string() | binary()
Base64 = base64_binary()
Base64String = base64_string()

Encodes a plain ASCII string into base64 using the standard alphabet according to RFC 4648 Section 4. The result is 33% larger than the data.

Always appends correct number of = padding characters to the encoded string.


encode(Data, Options) -> Base64


encode_to_string(Data, Options) -> Base64String

Types:

Data = byte_string() | binary()
Options = options()
Base64 = base64_binary()
Base64String = base64_string()

Encodes a plain ASCII string into base64 using the alphabet indicated by the mode option. The result is 33% larger than the data.

The mode option can be one of the following:

standard:: Default. Encode the given string using the standard base64 alphabet according to RFC 4648 Section 4.
urlsafe:: Encode the given string using the alternative "URL and Filename safe" base64 alphabet according to RFC 4648 Section 5.

The padding option can be one of the following:

true:: Default. Appends correct number of = padding characters to the encoded string.
false:: Skips appending = padding characters to the encoded string.