### ----------------------------------------------------
### -- PDF::ISO_32000
### -- Licenses: Artistic-2.0
### -- Authors: David Warring
### -- File: resources/ISO_32000/Table_252-Entries_in_a_signature_dictionary.json
### ----------------------------------------------------
{
  "table": {
    "caption": "Table 252 – Entries in a signature dictionary",
    "head": [
      "Key",
      "Type",
      "Value"
    ],
    "rows": [
      [
        "Type",
        "name",
        "(Optional) The type of PDF object that this dictionary describes; if present, is Sig for a signature dictionary."
      ],
      [
        "Filter",
        "name",
        "(Required; inheritable) The name of the preferred signature handler to use when validating this signature. If the Prop_Build entry is not present, it is also the name of the signature handler that was used to create the signature. If Prop_Build is present, it may be used to determine the name of the handler that created the signature (which is typically the same as Filter but is not needed to be). A conforming reader may substitute a different handler when verifying the signature, as long as it supports the specified SubFilter format. Example signature handlers are Adobe.PPKLite, Entrust.PPKEF, CICI.SignIt, and VeriSign.PPKVS. The name of the filter (i.e. signature handler) is identified in accordance with the rules defined in Annex E."
      ],
      [
        "SubFilter",
        "name",
        "(Optional) A name that describes the encoding of the signature value and key information in the signature dictionary. A conforming reader may use any handler that supports this format to validate the signature.\n(PDF 1.6) The following values for public-key cryptographic signatures is used: adbe.x509.rsa_sha1, adbe.pkcs7.detached, and adbe.pkcs7.sha1 (see 12.8.3, “Signature Interoperability”). Other values may be defined by developers, and when used, is prefixed with the registered developer identification. All prefix names is registered (see Annex E). The prefix “adbe” has been registered by Adobe Systems and the three subfilter names listed above and defined in 12.8.3, “Signature Interoperability“ may be used by any developer."
      ],
      [
        "Contents",
        "byte string",
        "(Required) The signature value. When ByteRange is present, the value is a hexadecimal string (see 7.3.4.3, “Hexadecimal Strings”) representing the value of the byte range digest.\nFor public-key signatures, Contents is either a DER-encoded PKCS1 binary data object or a DER-encoded PKCS7 binary data object.\nSpace for the Contents value must be allocated before the message digest is computed. (See 7.3.4, “String Objects“)"
      ],
      [
        "Cert",
        "array or byte string",
        "(Required when SubFilter is adbe.x509.rsa_sha1) An array of byte strings that represents the X.509 certificate chain used when signing and verifying signatures that use public-key cryptography, or a byte string if the chain has only one entry. The signing certificate appears first in the array; it is used to verify the signature value in Contents, and the other certificates is used to verify the authenticity of the signing certificate.\nIf SubFilter is adbe.pkcs7.detached or adbe.pkcs7.sha1, this entry is not used, and the certificate chain is put in the PKCS7 envelope in Contents."
      ],
      [
        "ByteRange",
        "array",
        "(Required for all signatures that are part of a signature field and usage rights signatures referenced from the UR3 entry in the permissions dictionary) An array of pairs of integers (starting byte offset, length in bytes) that describes the exact byte range for the digest calculation. Multiple discontiguous byte ranges is used to describe a digest that does not include the signature value (the Contents entry) itself."
      ],
      [
        "Reference",
        "array",
        "(Optional; PDF 1.5) An array of signature reference dictionaries (see Table 253)."
      ],
      [
        "Changes",
        "array",
        "(Optional) An array of three integers that specifies changes to the document that have been made between the previous signature and this signature: in this order, the number of pages altered, the number of fields altered, and the number of fields filled in.\nThe ordering of signatures is determined by the value of ByteRange. Since each signature results in an incremental save, later signatures have a greater length value."
      ],
      [
        "Name",
        "text string",
        "(Optional) The name of the person or authority signing the document. This value is used only when it is not possible to extract the name from the signature.\nEXAMPLE 1 From the certificate of the signer."
      ],
      [
        "M",
        "date",
        "(Optional) The time of signing. Depending on the signature handler, this may be a normal unverified computer time or a time generated in a verifiable way from a secure time server.\nThis value is used only when the time of signing is not available in the signature.\nEXAMPLE 2 A time stamp can be embedded in a PKCS7 binary data object (see 12.8.3.3, “PKCS7 Signatures as used in ISO 32000”)."
      ],
      [
        "Location",
        "text string",
        "(Optional) The CPU host name or physical location of the signing."
      ],
      [
        "Reason",
        "text string",
        "(Optional) The reason for the signing, such as (I agree …)."
      ],
      [
        "ContactInfo",
        "text string",
        "(Optional) Information provided by the signer to enable a recipient to contact the signer to verify the signature.\nEXAMPLE 3 A phone number."
      ],
      [
        "R",
        "integer",
        "(Optional) The version of the signature handler that was used to create the signature. (PDF 1.5) This entry is not used, and the information is stored in the Prop_Build dictionary."
      ],
      [
        "V",
        "integer",
        "(Optional; PDF 1.5) The version of the signature dictionary format. It corresponds to the usage of the signature dictionary in the context of the value of SubFilter. The value is 1 if the Reference dictionary is considered critical to the validation of the signature.\nDefault value: 0."
      ],
      [
        "Prop_Build",
        "dictionary",
        "(Optional; PDF 1.5) A dictionary that may be used by a signature handler to record information that captures the state of the computer environment used for signing, such as the name of the handler used to create the signature, software build date, version, and operating system.\nhe PDF Signature Build Dictionary Specification, provides implementation guidelines for the use of this dictionary."
      ],
      [
        "Prop_AuthTime",
        "integer",
        "(Optional; PDF 1.5) The number of seconds since the signer was last authenticated, used in claims of signature repudiation. It is omitted if the value is unknown."
      ],
      [
        "Prop_AuthType",
        "name",
        "(Optional; PDF 1.5) The method that is used to authenticate the signer, used in claims of signature repudiation. Valid values is PIN, Password, and Fingerprint."
      ]
    ]
  }
}


