Sealed boxes | Libsodium documentation

Only the recipient can decrypt these messages using their private key. While the recipient can verify the integrity of the message, they cannot verify the identity of the sender. A message is encrypted using an ephemeral key pair, with the secret key being erased right after the encryption process. Without knowing the secret key used for a given message, the sender cannot decrypt the message later. Furthermore, without additional data, a message cannot be correlated with the identity of its sender. The crypto_box_seal() function encrypts a message m of length mlen for a recipient whose public key is pk. It puts the ciphertext, whose length is crypto_box_SEALBYTES + mlen, into c. The function creates a new key pair for each message and attaches the public key to the ciphertext. The secret key is overwritten and is not accessible after this function returns. The crypto_box_seal_open() function decrypts the ciphertext c, whose length is clen, using the key pair (pk, sk) and puts the decry

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