# BR-KSA-28

Source: https://xmlvalid.com/rules/BR-KSA-28

> If the cryptographic stamp (KSA-15) exists in the invoice, this cryptographic stamp (KSA-15) must contain the exact "urn:oasis:names:specification:ubl:signature:1" value for signature information ID.

- Level: error
- Rule sets: ZATCA e-invoicing rules (Saudi Arabia) SDK 3.4.6
- Context: `cac:AdditionalDocumentReference/cac:Attachment`
- Test: `exists(cbc:EmbeddedDocumentBinaryObject) and (cbc:EmbeddedDocumentBinaryObject) != '' and (//ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/sig:UBLDocumentSignatures/sac:SignatureInformation/cbc:ID) = 'urn:oasis:names:specification:ubl:signature:1'`

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