Hybrid KEM Decapsulate

Category: Post-Quantum Cryptography · Node Type ID: pqc-hybridkem-decaps

Decapsulates shared secret using hybrid secret key and ciphertext

Overview

Decapsulates a 1,120-byte X25519 + ML-KEM-768 hybrid ciphertext using the recipient's 2,432-byte Hybrid Secret Key, recovering the exact same 32-byte combined Recovered Shared Secret produced by Hybrid KEM Encapsulate.

When to Use

Recovering the 32-byte combined shared secret on the recipient side of an X25519 + ML-KEM-768 hybrid key exchange.

Parameter Configuration

Hybrid KEM Decapsulate has no configurable parameters.

Port I/O Specification

See Ports & Connections for general wiring rules, data type colors, and dynamic port creation.

Input Ports

Port Nature: Fixed Input Ports (2 total).

Port Name	Port ID	Data Type	Required	Visibility Condition	Description
`Hybrid Secret Key`	`secretKey`	`Bytes`	Required	Always visible	Recipient's 2,432-byte `Hybrid Secret Key`.
`Hybrid Ciphertext`	`ciphertext`	`Bytes`	Required	Always visible	1,120-byte `Hybrid Ciphertext` received from the sender.

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Recovered Shared Secret`	`sharedSecret`	`Bytes`	Always visible	Recovered 32-byte combined shared secret.

Error Cases

When any of the following conditions occurs at runtime, this node transitions to an ERROR state and downstream nodes connected to its outputs do not execute.

Error Code	Default Engine Message	Trigger Condition
`INVALID_KEY_MATERIAL`	Invalid key length or format	Raised when `Hybrid Secret Key` is not 2,432 bytes or `Hybrid Ciphertext` is not 1,120 bytes.

Examples

Decapsulating a Hybrid KEM Ciphertext

Recover the 32-byte hybrid shared secret on the recipient side.

Connect Hybrid Secret Key from Hybrid KEM KeyGen and Hybrid Ciphertext from Hybrid KEM Encapsulate to Hybrid KEM Decapsulate.