Trait tink_core::HybridDecrypt

pub trait HybridDecrypt: HybridDecryptBoxClone {
    fn decrypt(
        &self, 
        ciphertext: &[u8], 
        context_info: &[u8]
    ) -> Result<Vec<u8>, TinkError>;
}

HybridDecrypt is the interface for hybrid decryption.

Hybrid Encryption combines the efficiency of symmetric encryption with the convenience of public-key encryption: to encrypt a message a fresh symmetric key is generated and used to encrypt the actual plaintext data, while the recipient’s public key is used to encrypt the symmetric key only, and the final ciphertext consists of the symmetric ciphertext and the encrypted symmetric key.

WARNING

Hybrid Encryption does not provide authenticity, that is the recipient of an encrypted message does not know the identity of the sender. Similar to general public-key encryption schemes the security goal of Hybrid Encryption is to provide privacy only. In other words, Hybrid Encryption is secure if and only if the recipient can accept anonymous messages or can rely on other mechanisms to authenticate the sender.

Security guarantees

The functionality of Hybrid Encryption is represented as a pair of primitives (traits): HybridEncrypt for encryption of data, and HybridDecrypt for decryption. Implementations of these traits are secure against adaptive chosen ciphertext attacks. In addition to plaintext the encryption takes an extra parameter contextInfo, which usually is public data implicit from the context, but should be bound to the resulting ciphertext, i.e. the ciphertext allows for checking the integrity of context_info (but there are no guarantees wrt. the secrecy or authenticity of context_info).

context_info can be empty, but to ensure the correct decryption of a ciphertext the same value must be provided for the decryption operation as was used during encryption (HybridEncrypt).

A concrete implementation of this trait can implement the binding of context_info to the ciphertext in various ways, for example:

• use context_info as "associated data"-input for the employed AEAD symmetric encryption (cf. RFC 5116).
• use context_info as "CtxInfo"-input for HKDF (if the implementation uses HKDF as key derivation function, cf. RFC 5869).

Required methods

fn decrypt(
    &self,
    ciphertext: &[u8],
    context_info: &[u8]
) -> Result<Vec<u8>, TinkError>

Decrypt ciphertext verifying the integrity of context_info. Returns resulting plaintext

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Implementors

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