diff --git a/doc/api/crypto.markdown b/doc/api/crypto.markdown index 6ef2de7fdc9641..fdc5123fe52dd4 100644 --- a/doc/api/crypto.markdown +++ b/doc/api/crypto.markdown @@ -719,6 +719,28 @@ console.log(sign.sign(private_key, 'hex')); // Prints the calculated signature ``` +A [`sign`][] instance can also be created by just passing in the digest +algorithm name, in which case OpenSSL will infer the full signature algorithm +from the type of the PEM-formatted private key, including algorithms that +do not have directly exposed name constants, e.g. 'ecdsa-with-SHA256'. + +Example: signing using ECDSA with SHA256 + +```js +const crypto = require('crypto'); +const sign = crypto.createSign('sha256'); + +sign.update('some data to sign'); + +const private_key = '-----BEGIN EC PRIVATE KEY-----\n' + + 'MHcCAQEEIF+jnWY1D5kbVYDNvxxo/Y+ku2uJPDwS0r/VuPZQrjjVoAoGCCqGSM49\n' + + 'AwEHoUQDQgAEurOxfSxmqIRYzJVagdZfMMSjRNNhB8i3mXyIMq704m2m52FdfKZ2\n' + + 'pQhByd5eyj3lgZ7m7jbchtdgyOF8Io/1ng==\n' + + '-----END EC PRIVATE KEY-----\n'; + +console.log(sign.sign(private_key).toString('hex')); +``` + ### sign.sign(private_key[, output_format]) Calculates the signature on all the data passed through using either