O1JS Base64 Encode/Decode

This repository offers a straightforward API to encode & decode base64-encoded input bytes. It's designed to be an easy-to-use and reliable tool for encoding & decoding base64 data in various projects using o1js.

How to use the package

Install the package

npm install o1js-base64

Import the provable type Bytes from o1js

import { Bytes } from 'o1js';

Base64 Decode

1. Import the base64Decode function

import { base64Decode } from 'o1js-base64';

2. For the example of a string input:

const encodedB64 = Bytes.fromString('7xQM+vU=');
const decodedB64 = base64Decode(encodedB64, 5);

Base64 Encode

1. Import the base64Encode function

import { base64Encode } from 'o1js-base64';

2. For the example of a string input:

const inputBytes = Bytes.fromString('Childish Monderino');
const encodedB64 = base64Encode(inputBytes);

Notes

• The base64Encode and base64Decode functions are interchangeable, but base64Encode is slightly more efficient.

• The base64Decode function will throw an error if the encodedB64 length is not a multiple of 4 or contains non-base64 characters.

• Ensure to provide the accurate decoded byte length parameter when invoking the base64Decode function.

• Utilize the calculateB64DecodedBytesLength function available within the package.

  • You can find an example of its usage in this code snippet.

  • If needed, you can refer to this gist for manual calculation guidance.

• When employing the base64Decode function within a zkProgram or zkApp, it's crucial to use the appropriate provable Byte types for both input and output.

  • For reference, consider this snippet, which demonstrates a zkProgram designed to decode a base64-encoded SHA256 digest.
  • The encoded input has a length of 44, while the expected decoded output is 32 bytes long.
  • Hence, it's crucial to accurately and deterministically assign provable Byte types to match the input and output lengths.
  • Similarly, for base64 Encode, ensure the same careful consideration of Byte types.

How to build

npm run build

How to run tests

npm run test
npm run testw # watch mode

How to run coverage

npm run coverage

How to benchmark

npm run benchmark

Preview

Base64 Decode zkProgram

| Summary | | | ------------- | ---- | | Total rows | 2138 | | Generic | 1522 | | EndoMulScalar | 616 |

| Action | Time (s) | | ------- | -------- | | Compile | 1.104 | | Prove | 11.219 | | Verify | 0.844 |

Base64 Encode zkProgram

| Summary | | | ------------- | ---- | | Total rows | 1697 | | Generic | 1203 | | EndoMulScalar | 494 |

| Action | Time (s) | | ------- | -------- | | Compile | 0.667 | | Prove | 9.383 | | Verify | 1.047 |

Acknowledgement

• This repo is inspired by the circom base64 implementation.

• Big thanks to Gregor Mitscha-Baude for highlighting the inefficiency in processing full field elements.

  • By operating on UInt8 instead of full field elements, the base64Decode circuit rows were reduced by around 75% from 8081 to 2138.

License

Apache-2.0