| // Copyright (c) HashiCorp, Inc. |
| // SPDX-License-Identifier: MPL-2.0 |
| |
| package roottoken |
| |
| import ( |
| "crypto/rand" |
| "encoding/base64" |
| "fmt" |
| |
| "github.com/hashicorp/go-secure-stdlib/base62" |
| ) |
| |
| // DefaultBase64EncodedOTPLength is the number of characters that will be randomly generated |
| // before the Base64 encoding process takes place. |
| const defaultBase64EncodedOTPLength = 16 |
| |
| // GenerateOTP generates a random token and encodes it as a Base64 or as a Base62 encoded string. |
| // Returns 0 if the generation completed without any error, 2 otherwise, along with the error. |
| func GenerateOTP(otpLength int) (string, error) { |
| switch otpLength { |
| case 0: |
| // This is the fallback case |
| buf := make([]byte, defaultBase64EncodedOTPLength) |
| readLen, err := rand.Read(buf) |
| if err != nil { |
| return "", fmt.Errorf("error reading random bytes: %s", err) |
| } |
| |
| if readLen != defaultBase64EncodedOTPLength { |
| return "", fmt.Errorf("read %d bytes when we should have read 16", readLen) |
| } |
| |
| return base64.StdEncoding.EncodeToString(buf), nil |
| default: |
| otp, err := base62.Random(otpLength) |
| if err != nil { |
| return "", fmt.Errorf("error reading random bytes: %w", err) |
| } |
| |
| return otp, nil |
| } |
| } |