ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])

• key <string> | <Buffer> | <TypedArray> | <DataView>
• curve <string>
• inputEncoding <string> key 字符串的编码。
• outputEncoding <string> 返回值的编码。
• format <string> 默认值: 'uncompressed'
• 返回: <Buffer> | <string>

将 key 和 curve 指定的 EC Diffie-Hellman 公钥转换为 format 指定的格式。 format 参数指定点编码，可以是 'compressed'、'uncompressed' 或 'hybrid'。 提供的密钥使用指定的 inputEncoding 进行解释，返回的密钥使用指定的 outputEncoding 进行编码。

使用 crypto.getCurves() 获取可用曲线名称的列表。 在最近的 OpenSSL 版本中，openssl ecparam -list_curves 还将显示每个可用椭圆曲线的名称和描述。

如果未指定 format，该点将以 'uncompressed' 格式返回。

如果未提供 inputEncoding，则 key 应为 Buffer、TypedArray 或 DataView。

示例（解压缩密钥）：

const { createECDH, ECDH } = require('crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// 转换后的密钥和未压缩的公钥应该是一样的
console.log(uncompressedKey === ecdh.getPublicKey('hex'));

• key <string> | <Buffer> | <TypedArray> | <DataView>
• curve <string>
• inputEncoding <string> The encoding of the key string.
• outputEncoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string>

Converts the EC Diffie-Hellman public key specified by key and curve to the format specified by format. The format argument specifies point encoding and can be 'compressed', 'uncompressed' or 'hybrid'. The supplied key is interpreted using the specified inputEncoding, and the returned key is encoded using the specified outputEncoding.

Use crypto.getCurves() to obtain a list of available curve names. On recent OpenSSL releases, openssl ecparam -list_curves will also display the name and description of each available elliptic curve.

If format is not specified the point will be returned in 'uncompressed' format.

If the inputEncoding is not provided, key is expected to be a Buffer, TypedArray, or DataView.

Example (uncompressing a key):

const { createECDH, ECDH } = require('crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// The converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));