base64-1.0: A modern Base64 library

Copyright | (c) 2019-2023 Emily Pillmore
License | BSD-style
Maintainer | Emily Pillmore <emilypi@cohomolo.gy>
Stability | stable
Portability | non-portable
Safe Haskell | None
Language | Haskell2010

Data.ByteString.Base64.URL

Contents

- Encoding
- Decoding
- Validation

Description

This module contains `ByteString`-valued combinators for implementing the RFC 4648 specification of the url-safe Base64 (Base64url) encoding format. This includes strictly padded/unpadded and lenient decoding variants, as well as internal and external validation for canonicity.

Synopsis

- encodeBase64 :: ByteString -> Base64 'UrlPadded Text
- encodeBase64' :: ByteString -> Base64 'UrlPadded ByteString
- encodeBase64Unpadded :: ByteString -> Base64 'UrlUnpadded Text
- encodeBase64Unpadded' :: ByteString -> Base64 'UrlUnpadded ByteString
- decodeBase64 :: forall (k :: Alphabet). UrlAlphabet k => Base64 k ByteString -> ByteString
- decodeBase64Untyped :: ByteString -> Either Text ByteString
- decodeBase64Unpadded :: Base64 'UrlUnpadded ByteString -> ByteString
- decodeBase64UnpaddedUntyped :: ByteString -> Either Text ByteString
- decodeBase64Padded :: Base64 'UrlPadded ByteString -> ByteString
- decodeBase64PaddedUntyped :: ByteString -> Either Text ByteString
- decodeBase64Lenient :: ByteString -> ByteString
- isBase64Url :: ByteString -> Bool
- isValidBase64Url :: ByteString -> Bool

# Encoding

encodeBase64 :: ByteString -> Base64 'UrlPadded Text #

Encode a `ByteString` value as a Base64url `Text` value with padding.

See: RFC-4648 section 5

### Examples:

    >>> encodeBase64 "<<?>>"
    "PDw_Pj4="

encodeBase64' :: ByteString -> Base64 'UrlPadded ByteString #

Encode a `ByteString` as a Base64url `ByteString` value with padding.

See: RFC-4648 section 5

### Examples:

    >>> encodeBase64' "<<?>>"
    "PDw_Pj4="

encodeBase64Unpadded :: ByteString -> Base64 'UrlUnpadded Text #

Encode a `ByteString` value as Base64url `Text` without padding. Note that for Base64url, padding is optional. If you call this function, you will simply be encoding as Base64url and stripping padding chars from the output.

See: RFC-4648 section 3.2

### Examples:

    >>> encodeBase64Unpadded "<<?>>"
    "PDw_Pj4"

encodeBase64Unpadded' :: ByteString -> Base64 'UrlUnpadded ByteString #

Encode a `ByteString` value as Base64url without padding. Note that for Base64url, padding is optional. If you call this function, you will simply be encoding as Base64url and stripping padding chars from the output.

See: RFC-4648 section 3.2

### Examples:

    >>> encodeBase64Unpadded' "<<?>>"
    "PDw_Pj4"

# Decoding

decodeBase64 :: forall (k :: Alphabet). UrlAlphabet k => Base64 k ByteString -> ByteString #

Decode a Base64url encoded `ByteString` value, either padded or unpadded. The correct decoding function is dispatched based on the existence of padding.

For typed values: - If a padded value is required, use `decodeBase64Padded` - If an unpadded value is required, use `decodeBase64Unpadded`

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64 $ assertBase64 @'UrlPadded "PDw_Pj4="
    "<<?>>"

    >>> decodeBase64 $ assertBase64 @'UrlUnpadded "PDw_Pj4"
    "<<?>>"

decodeBase64Untyped :: ByteString -> Either Text ByteString #

Decode an untyped Base64url encoded `ByteString` value. If its length is not a multiple of 4, then padding chars will be added to fill out the input to a multiple of 4 for safe decoding as Base64url-encoded values are optionally padded.

For a decoder that fails to decode untyped values of incorrect size: - If a padded value is required, use `decodeBase64PaddedUntyped` - If an unpadded value is required, use `decodeBase64UnpaddedUntyped`

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64Untyped "PDw_Pj4="
    Right "<<?>>"

    >>> decodeBase64Untyped "PDw_Pj4"
    Right "<<?>>"

    >>> decodeBase64Untyped "PDw-Pg="
    Left "Base64-encoded bytestring has invalid padding"

    >>> decodeBase64Untyped "PDw-Pg"
    Right "<<>>"

decodeBase64Unpadded :: Base64 'UrlUnpadded ByteString -> ByteString #

Decode an unpadded Base64url-encoded `ByteString` value. Input strings are required to be unpadded, and will undergo validation prior to decoding to confirm.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64Unpadded $ assertBase64 @'UrlUnpadded "PDw_Pj4"
    "<<?>>"

decodeBase64UnpaddedUntyped :: ByteString -> Either Text ByteString #

Decode an unpadded, untyped Base64url-encoded `ByteString` value. Input strings are required to be unpadded, and will undergo validation prior to decoding to confirm.

In general, unless unpadded Base64url is explicitly required, it is safer to call `decodeBase64Untyped`.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64UnpaddedUntyped "PDw_Pj4"
    Right "<<?>>"

    >>> decodeBase64UnpaddedUntyped "PDw_Pj4="
    Left "Base64-encoded bytestring has invalid padding"

decodeBase64Padded :: Base64 'UrlPadded ByteString -> ByteString #

Decode a padded Base64url-encoded `ByteString` value. Input strings are required to be correctly padded, and will be validated prior to decoding to confirm.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64Padded $ assertBase64 @'UrlPadded "PDw_Pj4="
    "<<?>>"

decodeBase64PaddedUntyped :: ByteString -> Either Text ByteString #

Decode a padded, untyped Base64url-encoded `ByteString` value. Input strings are required to be correctly padded, and will be validated prior to decoding to confirm.

In general, unless padded Base64url is explicitly required, it is safer to call `decodeBase64Untyped`.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64PaddedUntyped "PDw_Pj4="
    Right "<<?>>"

decodeBase64Lenient :: ByteString -> ByteString #

Leniently decode an unpadded, untyped Base64url-encoded `ByteString`. 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:

    >>> decodeBase64Lenient "PDw_Pj4="
    "<<?>>"

    >>> decodeBase64Lenient "PDw_%%%$}Pj4"
    "<<?>>"

# Validation

isBase64Url :: ByteString -> Bool #

Tell whether a `ByteString` is encoded in padded or unpadded Base64url format.

This function will also detect non-canonical encodings such as `ZE==`, which are externally valid Base64url-encoded values, but are internally inconsistent "impossible" values.

### Examples:

    >>> isBase64Url "PDw_Pj4="
    True

    >>> isBase64Url "PDw_Pj4"
    True

    >>> isBase64Url "PDw_Pj"
    False

isValidBase64Url :: ByteString -> Bool #

Tell whether a `ByteString` is a valid Base64url format.

This will not tell you whether or not this is a correct Base64url representation, only that it conforms to the correct shape. To check whether it is a true Base64 encoded `ByteString` value, use `isBase64Url`.

### Examples:

    >>> isValidBase64Url "PDw_Pj4="
    True

    >>> isValidBase64Url "PDw_Pj"
    True

    >>> isValidBase64Url "%"
    False