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What is an authentication value?

NOTE: This guidance reflects minor correction(s) (e.g., for grammar, typographical errors, or consistency) made on March 10, 2022.


Question: What is an authentication value?

Answer: The purpose of the authentication value is to provide a mechanism for cross-checking a transmitted electronic logging device (ELD) file’s authenticity. Below is one example of a pseudo-algorithm that could serve as the basis for generating an ELD authentication value:

  1. Extract some subject of the final ELD output file. This could be as little as a few fields or as much as the entire file (minus the ELD Authentication Value). Including the ELD Registration ID would satisfy the requirement that the ELD Authentication Value verify the ELD that generated the value.
  2. Use a standard signing algorithm. Generate a signature for this content using one of the certificates submitted during ELD registration.
  3. Convert this binary signature to a string using a string encoding algorithm that does not use any of the ELD reserved characters (comma—ASCII 44 and carriage return—ASCII 13).

Contact Info: FMCSA ELD Information, 1-800-832-5660 or 


 Note: This guidance document does not have the force and effect of law and is not meant to bind the public in any way.  It is intended only to provide information and clarity regarding existing requirements under the law or agency policies.

Regulatory Topic: ELD Guidance
Effective Date: Friday, September 1, 2017
Issued Date: Friday, September 1, 2017