(PureBasic) Verify and Unwrap S/MIME, and get Information about CMS Signature

Demonstrates calling the Verify method to verify and unwrap S/MIME. The MIME is restored to the original structure that it would have originally had prior to signing. The Verify method works with both detached signatures, as well as opaque/attached signatures.

Calls LastJsonData to get information about the signature(s) that were verified.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkDtObj.pb"
IncludeFile "CkMime.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    ; This example requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    mime.i = CkMime::ckCreate()
    If mime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Load the signed MIME from a file...
    success.i = CkMime::ckLoadMimeFile(mime,"qa_data/mime/detached_sig.eml")
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        ProcedureReturn
    EndIf

    ; Verify the S/MIME and restore the MIME
    ; to the structure/content it had prior to signing.
    verified.i = CkMime::ckVerify(mime)
    If verified = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        ProcedureReturn
    EndIf

    ; Examine the details of what was verified.
    json.i = CkMime::ckLastJsonData(mime)
    CkJsonObject::setCkEmitCompact(json, 0)
    Debug CkJsonObject::ckEmit(json)

    ; The code to parse the following JSON (i.e. extract desired information) is shown below..

    ; {
    ;   "pkcs7": {
    ;     "verify": {
    ;       "certs": [
    ;         {
    ;           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
    ;           "serial": "0702A21A85B84B659E180A6EE6F5A365"
    ;         },
    ;         {
    ;           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
    ;           "serial": "008B5B75568454850B00CFAF3848CEB1A4"
    ;         },
    ;         {
    ;           "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
    ;           "serial": "619C55C32FF6BD1A7B7E0330D21C8F3C"
    ;         }
    ;       ],
    ;       "digestAlgorithms": [
    ;         "sha1"
    ;       ],
    ;       "signerInfo": [
    ;         {
    ;           "cert": {
    ;             "serialNumber": "619C55C32FF6BD1A7B7E0330D21C8F3C",
    ;             "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
    ;             "digestAlgOid": "1.3.14.3.2.26",
    ;             "digestAlgName": "SHA1"
    ;           },
    ;           "contentType": "1.2.840.113549.1.7.1",
    ;           "signingTime": "160428055000Z",
    ;           "messageDigest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY=",
    ;           "signingAlgOid": "1.2.840.113549.1.1.1",
    ;           "signingAlgName": "RSA-PKCSV-1_5",
    ;           "authAttr": {
    ;             "1.2.840.113549.1.9.3": {
    ;               "name": "contentType",
    ;               "oid": "1.2.840.113549.1.7.1"
    ;             },
    ;             "1.2.840.113549.1.9.5": {
    ;               "name": "signingTime",
    ;               "utctime": "160428055000Z"
    ;             },
    ;             "1.2.840.113549.1.9.4": {
    ;               "name": "messageDigest",
    ;               "digest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY="
    ;             },
    ;             "1.2.840.113549.1.9.15": {
    ;               "der": "MFAwCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKA=="
    ;             },
    ;             "1.3.6.1.4.1.311.16.4": {
    ;               "der": "MIG7MIG...7fgMw0hyPPA=="
    ;             }
    ;           }
    ;         }
    ;       ]
    ;     }
    ;   }
    ; }

    ; Use this online tool to generate parsing code from sample JSON: 
    ; Generate Parsing Code from JSON

    signingTime.i = CkDtObj::ckCreate()
    If signingTime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    authAttrSigningTimeUtctime.i = CkDtObj::ckCreate()
    If authAttrSigningTimeUtctime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    issuerCN.s
    serial.s
    strVal.s
    certSerialNumber.s
    certIssuerCN.s
    certDigestAlgOid.s
    certDigestAlgName.s
    contentType.s
    messageDigest.s
    signingAlgOid.s
    signingAlgName.s
    authAttrContentTypeName.s
    authAttrContentTypeOid.s
    authAttrSigningTimeName.s
    authAttrMessageDigestName.s
    authAttrMessageDigestDigest.s
    authAttr1_2_840_113549_1_9_15Der.s
    authAttr1_3_6_1_4_1_311_16_4Der.s

    i.i = 0
    count_i.i = CkJsonObject::ckSizeOfArray(json,"pkcs7.verify.certs")
    While i < count_i
        CkJsonObject::setCkI(json, i)
        issuerCN = CkJsonObject::ckStringOf(json,"pkcs7.verify.certs[i].issuerCN")
        serial = CkJsonObject::ckStringOf(json,"pkcs7.verify.certs[i].serial")
        i = i + 1
    Wend
    i = 0
    count_i = CkJsonObject::ckSizeOfArray(json,"pkcs7.verify.digestAlgorithms")
    While i < count_i
        CkJsonObject::setCkI(json, i)
        strVal = CkJsonObject::ckStringOf(json,"pkcs7.verify.digestAlgorithms[i]")
        i = i + 1
    Wend
    i = 0
    count_i = CkJsonObject::ckSizeOfArray(json,"pkcs7.verify.signerInfo")
    While i < count_i
        CkJsonObject::setCkI(json, i)
        certSerialNumber = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].cert.serialNumber")
        certIssuerCN = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].cert.issuerCN")
        certDigestAlgOid = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].cert.digestAlgOid")
        certDigestAlgName = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].cert.digestAlgName")
        contentType = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].contentType")
        CkJsonObject::ckDtOf(json,"pkcs7.verify.signerInfo[i].signingTime",0,signingTime)
        messageDigest = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].messageDigest")
        signingAlgOid = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].signingAlgOid")
        signingAlgName = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].signingAlgName")
        authAttrContentTypeName = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.3" + Chr(34) + ".name")
        authAttrContentTypeOid = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.3" + Chr(34) + ".oid")
        authAttrSigningTimeName = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.5" + Chr(34) + ".name")
        CkJsonObject::ckDtOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.5" + Chr(34) + ".utctime",0,authAttrSigningTimeUtctime)
        authAttrMessageDigestName = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.4" + Chr(34) + ".name")
        authAttrMessageDigestDigest = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.4" + Chr(34) + ".digest")
        authAttr1_2_840_113549_1_9_15Der = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.2.840.113549.1.9.15" + Chr(34) + ".der")
        authAttr1_3_6_1_4_1_311_16_4Der = CkJsonObject::ckStringOf(json,"pkcs7.verify.signerInfo[i].authAttr." + Chr(34) + "1.3.6.1.4.1.311.16.4" + Chr(34) + ".der")
        i = i + 1
    Wend

    CkJsonObject::ckDispose(json)



    CkMime::ckDispose(mime)
    CkDtObj::ckDispose(signingTime)
    CkDtObj::ckDispose(authAttrSigningTimeUtctime)


    ProcedureReturn
EndProcedure