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Hola Greg, como puedo hacer eso? Encontré este video en youtube 

Pero no se si aplica con GLPI.

Of course they can be validated, in the case of wacom there is a solution to validate the signatures

Dynamic Signature Verification (DSV)

DSV is software that uses the assessment of dynamic data including variables such as pen direction, stroke sequence, pen up movement, pressure, speed, etc., to help verify the authenticity of signatures. By embedding a solution enabled with the DSV SDK within a Wacom tablet that is used to generate the signatures, this data can be used to compare two signatures with a greater degree of accuracy. As a result, it becomes much more difficult for anyone to get away with signature fraud.

Kofax SignDoc

e-Signature Types

Trigger the e-signing process via click-to-sign or with handwritten signatures, the often preferred choice in face-to-face signing scenarios; signing triggered by handwritten signatures may include capture of biometric signals of the writing process according to the ISO/IEC 19794-7 standard; captured photos of signers and/or signer IDs may be added to document as ISO/IEC 32000-1 PDF standard compliant digital signatures