Key Agreement Introduction and Algorithm Specifications

Note:

Currently in the beta phase.

Introduction to Key Agreement

To prevent malicious third parties from obtaining confidential information, the key itself cannot be directly transmitted between devices. Generally, a key agreement method is adopted to securely share the key between two (or multiple) parties. During key agreement, only the public key portion of the key is transmitted, while the private key remains stored within the device to ensure data security and confidentiality.

When performing key agreement between two devices, each party prepares an asymmetric key and exchanges the public keys of their asymmetric keys. The shared key is then derived using the peer's public key and the local private key, ensuring the same key is generated on both devices.

Note:

Lightweight devices do not support the key agreement function.

Supported Algorithms

The following are the specifications supported for key agreement.

For OpenHarmony vendor adaptation, the key management service specifications are divided into mandatory and optional specifications. Mandatory specifications are algorithm specifications that all vendors must support. For optional specifications, vendors decide whether to implement them based on actual circumstances. If needed, please refer to the specific vendor's documentation to ensure the specification is supported before use.

Developers are advised to use mandatory specifications for application development to ensure full platform compatibility.

Algorithm	Remarks	API Level	Mandatory Specification
ECDH	The agreed key type is an ECC-type key.	15+	Yes
DH	-	15+	Yes
X25519	-	15+	Yes