Crate ct_codecs

CT-Codecs

A Rust implementation of constant-time Base64 and Hexadecimal codecs, reimplemented from libsodium and libhydrogen.

Features

• Constant-time implementation for cryptographic applications where timing attacks are a concern
• Strict validation ensuring Base64 strings are not malleable
• Multiple variants of Base64: standard, URL-safe, with and without padding
• Character filtering for ignoring specific characters during decoding (like whitespace)
• Zero dependencies and no_std compatible
• Memory safety with #![forbid(unsafe_code)]

Usage Examples

Base64 Encoding

use ct_codecs::{Base64, Encoder};

fn example() -> Result<(), ct_codecs::Error> {
    let data = b"Hello, world!";
    let encoded = Base64::encode_to_string(data)?;
    assert_eq!(encoded, "SGVsbG8sIHdvcmxkIQ==");
    Ok(())
}

Base64 Decoding

use ct_codecs::{Base64, Decoder};

fn example() -> Result<(), ct_codecs::Error> {
    let encoded = "SGVsbG8sIHdvcmxkIQ==";
    let decoded = Base64::decode_to_vec(encoded, None)?;
    assert_eq!(decoded, b"Hello, world!");
    Ok(())
}

Hexadecimal Encoding/Decoding

use ct_codecs::{Hex, Encoder, Decoder};

fn example() -> Result<(), ct_codecs::Error> {
    let data = b"Hello, world!";
    let encoded = Hex::encode_to_string(data)?;
    let decoded = Hex::decode_to_vec(&encoded, None)?;
    assert_eq!(decoded, data);
    Ok(())
}

No-std Usage with Pre-allocated Buffers

use ct_codecs::{Base64, Encoder, Decoder};

fn example() -> Result<(), ct_codecs::Error> {
    let data = b"Hello, world!";
    let mut encoded_buf = [0u8; 20]; // Must be large enough
    let encoded = Base64::encode(&mut encoded_buf, data)?;
     
    let mut decoded_buf = [0u8; 13]; // Must be large enough
    let decoded = Base64::decode(&mut decoded_buf, encoded, None)?;
    assert_eq!(decoded, data);
    Ok(())
}

Structs

Base64

Standard Base64 encoder and decoder with padding.

Base64NoPadding

Standard Base64 encoder and decoder without padding.

Base64UrlSafe

URL-safe Base64 encoder and decoder with padding.

Base64UrlSafeNoPadding

URL-safe Base64 encoder and decoder without padding.

Hex

Hexadecimal encoder and decoder implementation.

Enums

Error

Error type for ct-codecs operations.

Traits

Decoder

Trait for decoding text representations back into binary data.

Encoder

Trait for encoding binary data into text representations.

Functions

verify

Constant-time equality check for two byte slices.