Crate base64 

Fast base64 encoding and decoding with SIMD acceleration, constant-time operations, and const fn support.

Four alphabet variants are available via Alphabet:

Variant	Characters	Padding
Standard	A-Za-z0-9+/	=
StandardNoPadding	A-Za-z0-9+/	none
Url	A-Za-z0-9-_	=
UrlNoPadding	A-Za-z0-9-_	none

Feature flags

Flag	Description
std	std::error::Error trait impls (enabled by default)
alloc	String/Vec-returning convenience APIs
serde	Serde serialize/deserialize helpers

Performance

The encode_into and decode_into functions automatically dispatch to SIMD-accelerated paths (AVX2 on x86/x86_64, NEON on aarch64). When a constant-time guarantee is required, use encode_into_constant_time or decode_into_constant_time.

const fn support

encode_array and decode_array are const fn, enabling base64 encoding and decoding at compile time.

Examples

use base64::{Alphabet, encode, decode};

let encoded = encode(b"hello world", Alphabet::Standard);
assert_eq!(encoded, "aGVsbG8gd29ybGQ=");

let decoded = decode(b"aGVsbG8gd29ybGQ=", Alphabet::Standard).unwrap();
assert_eq!(decoded, b"hello world");

let url = encode(b"hello world", Alphabet::Url);
assert_eq!(url, "aGVsbG8gd29ybGQ=");

Enums

Alphabet

The base64 alphabet used for encoding and decoding.

DecodeError

Errors that can occur during base64 decoding.

EncodeError

Errors that can occur during base64 encoding.

Functions

decodealloc

Decode Decodes a base64 string into bytes.

decode_array

Decodes a base64 string into a fixed-size array at compile time.

decode_into

Decodes a base64 string into an existing buffer.

decode_into_constant_time

Constant-time base64 decoding. Processes all input data without secret-dependent branches or memory accesses, making it suitable for cryptographic applications.

encodealloc

Encodes bytes to a base64 string using the given Alphabet.

encode_array

Encodes data into a fixed-size array at compile time.

encode_into

Encodes bytes into an existing buffer.

encode_into_constant_time

Constant-time base64 encoding. Processes all input data without secret-dependent branches or memory accesses, making it suitable for cryptographic applications.

encode_into_stringalloc

Appends the base64-encoded representation of data to a String.

encoded_length

Encode Returns the size in bytes of the input data after base64 encoding.