fromPem static method
Parses a PEM string into a private key.
Throws if pem is not a single PRIVATE KEY block holding an xDSA
private key. The block starts at the first byte, uses strict base64 and
ends all its lines in LF or all in CRLF.
Implementation
static SecretKey fromPem(String pem) =>
SecretKey._(ffi.XdsaSecretKey.fromPem(pem: pem));