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XChaCha20-Poly1305 Authenticated Encryption with Associated Data.

Defined in draft-irtf-cfrg-xchacha-01. See https://tools.ietf.org/html/draft-irtf-cfrg-xchacha-01

Hierarchy

  • XChaCha20Poly1305

Implements

  • AEAD

Index

Constructors

Properties

nonceLength: 24 = NONCE_LENGTH
tagLength: 16 = TAG_LENGTH

Methods

  • open(nonce: Uint8Array, sealed: Uint8Array, associatedData?: Uint8Array, dst?: Uint8Array): null | Uint8Array
  • Authenticates sealed ciphertext (which includes authentication tag) and associated data, decrypts ciphertext and returns decrypted plaintext.

    draft-irtf-cfrg-xchacha-01 defines a 24 byte nonce (192 bits) which then uses the first 16 bytes of the nonce and the secret key with Hchacha to generate an initial subkey. The last 8 bytes of the nonce are then prefixed with 4 zero bytes and then provided with the subkey to the chacha20poly1305 implementation.

    If authentication fails, it returns null.

    If dst is given (it must be the size of plaintext + the size of tag length) the result will be put into it. Dst and plaintext must not overlap.

    Parameters

    • nonce: Uint8Array
    • sealed: Uint8Array
    • Optional associatedData: Uint8Array
    • Optional dst: Uint8Array

    Returns null | Uint8Array

  • seal(nonce: Uint8Array, plaintext: Uint8Array, associatedData?: Uint8Array, dst?: Uint8Array): Uint8Array
  • Encrypts and authenticates plaintext, authenticates associated data, and returns sealed ciphertext, which includes authentication tag.

    draft-irtf-cfrg-xchacha-01 defines a 24 byte nonce (192 bits) which uses the first 16 bytes of the nonce and the secret key with HChaCha to generate an initial subkey. The last 8 bytes of the nonce are then prefixed with 4 zero bytes and then provided with the subkey to the ChaCha20Poly1305 implementation.

    If dst is given (it must be the size of plaintext + the size of tag length) the result will be put into it. Dst and plaintext must not overlap.

    Parameters

    • nonce: Uint8Array
    • plaintext: Uint8Array
    • Optional associatedData: Uint8Array
    • Optional dst: Uint8Array

    Returns Uint8Array

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