PsaCipherDecrypt

Decrypt a short message with a symmetric cipher. Opcode: 21 (0x0015)

Parameters

Name	Type	Description
`key_name`	String	Name of the key to use for the operation
`alg`	`Cipher`	A cipher algorithm that is compatible with the type of key
`ciphertext`	Vector of bytes	IV followed by the ciphertext

key_name must allow the usage flag decrypt.
ciphertext must be the IV followed by the ciphertext.

Results

Name	Type	Description
`plaintext`	Vector of bytes	Buffer containing decrypted message

Specific response status codes

PsaErrorNotPermitted: The key does not have the decrypt flag, or it does not permit the requested algorithm.
PsaErrorInvalidPadding: The decrypted padding is incorrect. See Warning below.

Description

This function will decrypt a short message using the provided initialisation vector (IV).

Warning: In some protocols, when decrypting data, it is essential that the behavior of the application does not depend on whether the padding is correct (see Klíma et al). Protocols that use authenticated encryption are recommended for use by applications, rather than plain encryption. If the application must perform a decryption of unauthenticated data, the application writer must take care not to reveal whether the padding is invalid.

Contract

Protobuf

The Parsec Book