base64
Copyright(c) 2019-2026 Emily Pillmore
LicenseBSD-style
MaintainerEmily Pillmore <emilypi@cohomolo.gy>
Stabilitystable
Portabilitynon-portable
Safe HaskellNone
LanguageHaskell2010

Data.Text.Lazy.Encoding.Base64.URL

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

Encoding

encodeBase64 :: Text -> Base64 'UrlPadded Text Source #

Encode a Text value in Base64url with padding.

See: RFC-4648 section 5

Examples:

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

encodeBase64Unpadded :: Text -> Base64 'UrlUnpadded Text Source #

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 :: forall (k :: Alphabet). UrlAlphabet k => Base64 k Text -> Text Source #

Decode an arbitrarily Base64url-encoded Text value.

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 :: Text -> Either Text Text Source #

Decode an untyped 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.

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 "<<>>"

decodeBase64UntypedWith Source #

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 untyped lazy 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'
  :: ByteString -> Either (Base64Error UnicodeException) Text

decodeBase64Unpadded :: Base64 'UrlUnpadded Text -> Text Source #

Decode an unpadded Base64url encoded Text value.

See: RFC-4648 section 4

Examples:

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

decodeBase64UnpaddedUntyped :: Text -> Either Text Text Source #

Decode an unpadded, untyped Base64url encoded Text value.

See: RFC-4648 section 4

Examples:

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

decodeBase64UnpaddedUntypedWith Source #

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, untyped lazy 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:

decodeBase64UnpaddedUntypedWith decodeUtf8'
  :: ByteString -> Either (Base64Error UnicodeException) Text

decodeBase64Padded :: Base64 'UrlPadded Text -> Text Source #

Decode a padded Base64url encoded Text value

See: RFC-4648 section 4

Examples:

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

decodeBase64PaddedUntyped :: Text -> Either Text Text Source #

Decode an untyped, padded Base64url encoded Text value

See: RFC-4648 section 4

Examples:

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

decodeBase64PaddedUntypedWith Source #

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, untyped lazy 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 Source #

Leniently decode an untyped 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"
"<<?>>"

Parsing

parseBase64Padded :: Text -> Either Text (Base64 'UrlPadded Text) Source #

Parse a canonical, padded Base64url-encoded Text value.

Checks the URL-safe alphabet, length, padding, and unused padding bits. Returns the original encoded value wrapped in Base64, ready for decodeBase64Padded or decodeBase64. Errors match the strict ByteString decodeBase64PaddedUntyped decoder. The input is neither decoded nor normalized in the returned value.

The entire input is validated before returning Right; the original chunk boundaries are preserved in the result.

This validates the Base64url encoding, independently of whether the decoded payload is valid UTF-8.

Examples:

>>> parseBase64Padded "PDw_Pj4="
Right "PDw_Pj4="
>>> fmap decodeBase64Padded (parseBase64Padded "PDw_Pj4=")
Right "<<?>>"
>>> parseBase64Padded "PDw_Pj4"
Left "Base64-encoded bytestring requires padding"
>>> parseBase64Padded "ZE=="
Left "non-canonical encoding detected at offset: 1"

Since: 2.1

parseBase64Unpadded :: Text -> Either Text (Base64 'UrlUnpadded Text) Source #

Parse a canonical, unpadded Base64url-encoded Text value.

Checks the URL-safe alphabet, length, padding, and unused padding bits. Returns the original encoded value wrapped in Base64, ready for decodeBase64Unpadded or decodeBase64. Errors match the strict ByteString decodeBase64UnpaddedUntyped decoder. The input is neither decoded nor normalized in the returned value.

The entire input is validated before returning Right; the original chunk boundaries are preserved in the result.

This validates the Base64url encoding, independently of whether the decoded payload is valid UTF-8.

Examples:

>>> parseBase64Unpadded "PDw_Pj4"
Right "PDw_Pj4"
>>> fmap decodeBase64Unpadded (parseBase64Unpadded "PDw_Pj4")
Right "<<?>>"
>>> parseBase64Unpadded "PDw_Pj4="
Left "Base64-encoded bytestring has invalid padding"
>>> parseBase64Unpadded "ZE"
Left "non-canonical encoding detected at offset: 1"

Since: 2.1