base64-0.4.2.4: A modern RFC 4648-compliant Base64 library

Copyright | (c) 2019-2020 Emily Pillmore
License | BSD-style
Maintainer | Emily Pillmore <emilypi@cohomolo.gy>
Stability | stable
Portability | non-portable
Safe Haskell | Safe
Language | Haskell2010

Data.Text.Encoding.Base64.URL

Contents

- Encoding
- Decoding
- Validation

Description

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

Synopsis

- encodeBase64 :: Text -> Text
- encodeBase64Unpadded :: Text -> Text
- decodeBase64 :: Text -> Either Text Text
- decodeBase64With :: (ByteString -> Either err Text) -> ByteString -> Either (Base64Error err) Text
- decodeBase64Unpadded :: Text -> Either Text Text
- decodeBase64UnpaddedWith :: (ByteString -> Either err Text) -> ByteString -> Either (Base64Error err) Text
- decodeBase64Padded :: Text -> Either Text Text
- decodeBase64PaddedWith :: (ByteString -> Either err Text) -> ByteString -> Either (Base64Error err) Text
- decodeBase64Lenient :: Text -> Text
- isBase64Url :: Text -> Bool
- isValidBase64Url :: Text -> Bool

# Encoding

encodeBase64 :: Text -> Text #

Encode a `Text` value in Base64url with padding.

See: RFC-4648 section 5

### Examples:

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

encodeBase64Unpadded :: Text -> Text #

Encode a `Text` value in 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 :: Text -> Either Text Text #

Decode a padded Base64url-encoded `Text` 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 encodings are optionally padded.

For a decoder that fails on unpadded input, use `decodeBase64Unpadded`

Note: This function makes sure that decoding is total by deferring to `decodeLatin1`. This will always round trip for any valid Base64-encoded text value, but it may not round trip for bad inputs. The onus is on the caller to make sure inputs are valid. If unsure, defer to `decodeBase64With` and pass in a custom decode function.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64 "PDw_Pj4="
    Right "<<?>>"

    >>> decodeBase64 "PDw_Pj4"
    Right "<<?>>"

    >>> decodeBase64 "PDw-Pg="
    Left "Base64-encoded bytestring has invalid padding"

    >>> decodeBase64 "PDw-Pg"
    Right "<<>>"

decodeBase64With #

Arguments

:: (ByteString -> Either err Text) | convert a bytestring to text (e.g. `decodeUtf8'`)
-> ByteString | Input text to decode
-> Either (Base64Error err) Text |

Attempt to decode a `ByteString` value as Base64url, converting from `ByteString` to `Text` according to some encoding function. In practice, This is something like `decodeUtf8'`, which may produce an error.

See: RFC-4648 section 4

### Examples:

    decodeBase64With decodeUtf8'
      :: Text -> Either (Base64Error UnicodeException) Text

decodeBase64Unpadded :: Text -> Either Text Text #

Decode an unpadded Base64url encoded `Text` value.

Note: This function makes sure that decoding is total by deferring to `decodeLatin1`. This will always round trip for any valid Base64-encoded text value, but it may not round trip for bad inputs. The onus is on the caller to make sure inputs are valid. If unsure, defer to `decodeBase64UnpaddedWith` and pass in a custom decode function.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64Unpadded "PDw_Pj4"
    Right "<<?>>"

    >>> decodeBase64Unpadded "PDw_Pj4="
    Left "Base64-encoded bytestring has invalid padding"

decodeBase64UnpaddedWith #

Arguments

:: (ByteString -> Either err Text) | convert a bytestring to text (e.g. `decodeUtf8'`)
-> ByteString | Input text to decode
-> Either (Base64Error err) Text |

Attempt to decode an unpadded `ByteString` value as Base64url, converting from `ByteString` to `Text` according to some encoding function. In practice, This is something like `decodeUtf8'`, which may produce an error.

See: RFC-4648 section 4

### Example:

    decodeBase64UnpaddedWith decodeUtf8'
      :: ByteString -> Either (Base64Error UnicodeException) Text

decodeBase64Padded :: Text -> Either Text Text #

Decode an padded Base64url encoded `Text` value

Note: This function makes sure that decoding is total by deferring to `decodeLatin1`. This will always round trip for any valid Base64-encoded text value, but it may not round trip for bad inputs. The onus is on the caller to make sure inputs are valid. If unsure, defer to `decodeBase64PaddedWith` and pass in a custom decode function.

See: RFC-4648 section 4

### Examples:

    >>> decodeBase64Padded "PDw_Pj4="
    Right "<<?>>"

    >>> decodeBase64Padded "PDw_Pj4"
    Left "Base64-encoded bytestring requires padding"

decodeBase64PaddedWith #

Arguments

:: (ByteString -> Either err Text) | convert a bytestring to text (e.g. `decodeUtf8'`)
-> ByteString | Input text to decode
-> Either (Base64Error err) Text |

Attempt to decode a padded `ByteString` value as Base64url, converting from `ByteString` to `Text` according to some encoding function. In practice, This is something like `decodeUtf8'`, which may produce an error.

See: RFC-4648 section 4

### Example:

    decodeBase64PaddedWith decodeUtf8'
      :: ByteString -> Either (Base64Error UnicodeException) Text

decodeBase64Lenient :: Text -> Text #

Leniently decode an unpadded Base64url-encoded `Text`. 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 :: Text -> Bool #

Tell whether a `Text` value is Base64url-encoded.

### Examples:

    >>> isBase64Url "PDw_Pj4="
    True

    >>> isBase64Url "PDw_Pj4"
    True

    >>> isBase64Url "PDw_Pj"
    False

isValidBase64Url :: Text -> Bool #

Tell whether a `Text` value 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 `Text` value, use `isBase64Url`.

### Examples:

    >>> isValidBase64Url "PDw_Pj4="
    True

    >>> isValidBase64Url "PDw_Pj"
    True

    >>> isValidBase64Url "%"
    False