Modulebase64-1.0Haskell2010

Data.ByteString.Lazy.Base64

This module contains ByteString-valued combinators for implementing the RFC 4648 specification of the Base64 encoding format. This includes lenient decoding variants, as well as internal and external validation for canonicity.

7 values

Packagebase64-1.0
Exports7
LanguageHaskell2010
LicenceBSD-3-Clause
SourceBase64.hs

Encoding

2 declarations

valueencodeBase64 :: ByteString -> Base64 'StdPadded Text

Encode a ByteString value as Base64 Text with padding.

See: RFC-4648 section 4

Examples:

Example1 expression

>>> encodeBase64 "Sun""U3Vu"

valueencodeBase64' :: ByteString -> Base64 'StdPadded ByteString

Encode a ByteString value as a Base64 ByteString value with padding.

See: RFC-4648 section 4

Examples:

Example1 expression

>>> encodeBase64' "Sun""U3Vu"

Decoding

3 declarations

valuedecodeBase64 :: StdAlphabet k => Base64 k ByteString -> ByteString

Decode a padded Base64-encoded ByteString value.

See: RFC-4648 section 4

Examples:

Example1 expression

>>> decodeBase64 $ assertBase64 @'StdPadded "U3Vu""Sun"

valuedecodeBase64Untyped :: ByteString -> Either Text ByteString

Decode a padded untyped Base64-encoded ByteString value.

See: RFC-4648 section 4

Examples:

Example1 expression

>>> decodeBase64Untyped "U3Vu"Right "Sun"

Example1 expression

>>> decodeBase64Untyped "U3V"Left "Base64-encoded bytestring requires padding"

Example1 expression

>>> decodeBase64Untyped "U3V="Left "non-canonical encoding detected at offset: 2"

valuedecodeBase64Lenient :: ByteString -> ByteString

Leniently decode an unpadded Base64-encoded ByteString value. This function will not generate parse errors. If input data contains padding chars, then the input will be parsed up until the first pad character.

Note: This is not RFC 4648-compliant.

Examples:

Example1 expression

>>> decodeBase64Lenient "U3Vu""Sun"

Example1 expression

>>> decodeBase64Lenient "U3V""Su"

Example1 expression

>>> decodeBase64Lenient "U3V=""Su"

Validation

2 declarations

valueisBase64 :: ByteString -> Bool

Tell whether a ByteString value is base64 encoded.

This function will also detect non-canonical encodings such as ZE==, which are externally valid Base64-encoded values, but are internally inconsistent "impossible" values.

Examples:

Example1 expression

>>> isBase64 "U3Vu"True

Example1 expression

>>> isBase64 "U3V"False

Example1 expression

>>> isBase64 "U3V="False

valueisValidBase64 :: ByteString -> Bool

Tell whether a ByteString value is a valid Base64 format.

This will not tell you whether or not this is a correct Base64 representation, only that it conforms to the correct shape. To check whether it is a true Base64 encoded ByteString value, use isBase64.

Examples:

Example1 expression

>>> isValidBase64 "U3Vu"True

Example1 expression

>>> isValidBase64 "U3V"True

Example1 expression

>>> isValidBase64 "U3V="True

Example1 expression

>>> isValidBase64 "%"False