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 | Trustworthy
Language | Haskell2010

Data.ByteString.Short.Base64.URL

Contents

- Encoding
- Decoding
- Validation

Description

This module contains `ShortByteString`-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 :: ShortByteString -> ShortText
- encodeBase64' :: ShortByteString -> ShortByteString
- encodeBase64Unpadded :: ShortByteString -> ShortText
- encodeBase64Unpadded' :: ShortByteString -> ShortByteString
- decodeBase64 :: ShortByteString -> Either Text ShortByteString
- decodeBase64Unpadded :: ShortByteString -> Either Text ShortByteString
- decodeBase64Padded :: ShortByteString -> Either Text ShortByteString
- decodeBase64Lenient :: ShortByteString -> ShortByteString
- isBase64Url :: ShortByteString -> Bool
- isValidBase64Url :: ShortByteString -> Bool

# Encoding

encodeBase64 :: ShortByteString -> ShortText #

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

See: RFC-4648 section 5

### Examples:

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

encodeBase64' :: ShortByteString -> ShortByteString #

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

See: RFC-4648 section 5

### Examples:

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

encodeBase64Unpadded :: ShortByteString -> ShortText #

Encode a `ShortByteString` 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' :: ShortByteString -> ShortByteString #

Encode a `ShortByteString` 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 :: ShortByteString -> Either Text ShortByteString #

Decode a padded Base64url encoded `ShortByteString` 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 on unpadded input of incorrect size, use `decodeBase64Unpadded`.

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 "<<>>"

decodeBase64Unpadded :: ShortByteString -> Either Text ShortByteString #

Decode an unpadded Base64url-encoded `ShortByteString` 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 `decodeBase64`.

See: RFC-4648 section 4

### Examples:

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

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

decodeBase64Padded :: ShortByteString -> Either Text ShortByteString #

Decode a padded Base64url-encoded `ShortByteString` 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 `decodeBase64`.

See: RFC-4648 section 4

### Examples:

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

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

decodeBase64Lenient :: ShortByteString -> ShortByteString #

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

Tell whether a `ShortByteString` is Base64url-encoded.

### Examples:

    >>> isBase64Url "PDw_Pj4="
    True

    >>> isBase64Url "PDw_Pj4"
    True

    >>> isBase64Url "PDw_Pj"
    False

isValidBase64Url :: ShortByteString -> Bool #

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

### Examples:

    >>> isValidBase64Url "PDw_Pj4="
    True

    >>> isValidBase64Url "PDw_Pj"
    True

    >>> isValidBase64Url "%"
    False