Calculating Lead Fingerprint

Learn about calculating and using a lead fingerprint in TrustedForm. For general information, check out Lead Fingerprinting.

TrustedForm will attempt to capture lead fingerprints with every certificate, allowing a consumer to be uniquely and anonymously tied to a certificate. TrustedForm stores each phone number and email address as a SHA1 hash based on the fields filled out on the offer form. Because these hashed values are hexadecimal strings, they do not collect or store personally identifiable information (PII).

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As a certificate is generated, the TrustedForm script watches the form for changes, and as the consumer enters information, it is examined for information that looks like a phone number or email address. Data identified as a phone number or email address will be converted into a SHA1 hash and stored as part of the certificate.

As part of the TrustedForm claim, you may either allow TrustedForm to calculate the fingerprints based on your lead fields, or you may calculate the fingerprints yourself, sending them in the optional fingerprint parameter (if you are claiming certificates directly via the API). If at least one of the fingerprints does not match, you will receive a warning in the claim response.

Let TrustedForm calculate the fingerprint for you

TrustedForm will calculate the fingerprints on your behalf when you pass some basic lead data in the claim call. TrustedForm will evaluate the included data and calculate SHA1 hashes of any phone numbers and email addresses, discarding the lead data once the hash is calculated.


In the following example, we include the phone_1, phone_2 and email fields in the claim request (see Claim API for details on this request). The name of the submitted fields is not relevant, and none of the fields are stored after being used in the lead fingerprint calculation.

LeadConduit and lead fingerprints

If you are a LeadConduit client, you may add the TrustedForm enhancement step to your flow. The TrustedForm enhancement step will automatically submit email and phone number fields to TrustedForm to calculate lead fingerprints. For more information on adding TrustedForm to LeadConduit, check out this walkthrough.

How to calculate fingerprints yourself

Calculate SHA1 hex digest of a phone number:

  1. Remove all non-digit characters (512-555-5785 becomes 5125555785)
  2. Trim any leading and trailing whitespace
  3. Take the SHA1 hex digest

Calculate SHA1 hex digest of an email:

  1. Downcase (convert to lowercase)
  2. Trim any leading and trailing whitespace
  3. Take the SHA1 hex digest


Given the following lead data, you'll calculate the fingerprints: fname=Tom&lname=Jones&

  1. "512-789-1111"
    1. Remove all non-digit characters and trim whitespace - 5127891111
    2. Calculate SHA1 - 12864b281c728bdca0f2102dba31308e1014fe4a
  2. "512.555.5785"
    1. Remove all non-digit characters and trim whitespace - 5125555785
    2. Calculate SHA1 - 921e1dbc260148681f6f14a966c3e3242a4d3912
  3. " ”
    1. Downcase the email - “ “
    2. Trim any leading and trailing whitespace - “”
    3. Calculate SHA1 - 03537b0556fa5ea9042b264d49def5c3457b4ed2

Include each fingerprint in its own fingerprint parameter:

Need more help?

Reach out to our support team at and they will be happy to help you with Lead Fingerprints.





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