Verify that the ciphertext includes a valid tag

# sodium_crypto_aead_chacha20poly1305_ietf_decrypt

(PHP 7 >= 7.2.0, PHP 8)

sodium_crypto_aead_chacha20poly1305_ietf_decrypt — Verify that the ciphertext includes a valid tag

### Description

sodium_crypto_aead_chacha20poly1305_ietf_decrypt(
string `$ciphertext`,
string `$additional_data`,
string `$nonce`,
#[\SensitiveParameter] string `$key`
): string|false

Verify then decrypt with ChaCha20-Poly1305 (IETF variant).

The IETF variant uses 96-bit nonces and 32-bit internal counters, instead of 64-bit for both.

### Parameters

`ciphertext`
  Must be in the format provided by sodium_crypto_aead_chacha20poly1305_ietf_encrypt() (ciphertext and tag, concatenated).
`additional_data`
  Additional, authenticated data. This is used in the verification of the authentication tag appended to the ciphertext, but it is not encrypted or stored in the ciphertext.
`nonce`
  A number that must be only used once, per message. 12 bytes long.
`key`
  Encryption key (256-bit).

### Return Values

Returns the plaintext on success, or `false` on failure.

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