accept a rand io.Reader. // // Any Reader that implements this interface is assumed to // call [Read] as its Read method. type DefaultReader interface{ defaultReader() } // ReadWithReader uses Reader to fill b with cryptographically secure random // bytes. It is intended for use in APIs that expose a rand io.Reader. func ReadWithReader(r io.Reader, b []byte) error { if _, ok := r.(DefaultReader); ok { Read(b) return nil } fips140.RecordNonApproved() _, err := io.ReadFull(r, b) return err } golang.org...

when passed to // APIs that accept a rand io.Reader. type DefaultReader interface{ defaultReader() } // ReadWithReader uses Reader to fill b with cryptographically secure random // bytes. It is intended for use in APIs that expose a rand io.Reader. // // If Reader is not the default Reader from crypto/rand, // [randutil.MaybeReadByte] and [fips140.RecordNonApproved] are called. func ReadWithReader(r io.Reader, b []byte) error { if _, ok := r.(DefaultReader); ok { Read(b) return nil } fips140.RecordNonApproved()...