ASN1_TextDump

Dumps details of ASN.1 formatted data to a text file

VBA/VB6 Syntax

nRet = ASN1_TextDump(strFileOut, strFileOrPEMString, nOptions)

C/C++ Syntax

Parameters

szFileOut

[in] filename of text file to be created.

szFileOrPEMString

[in] filename of ASN.1 formatted data file to be analyzed (or its base64 representation or PEM string).

nOptions

[in] option flags:
PKI_ASN1_NOCOMMENTS to hide the comments
PKI_ASN1_ADDLEVELS to show level numbers

Returns (VBA/C)

If successful, the return value is zero; otherwise it returns a nonzero error code.

.NET Equivalent

Asn1.TextDump Method

C++ (STL) Equivalent

Python Equivalent

Remarks

The input may be a binary file in BER/DER format or a text file in PEM or base64-encoded format, or may be passed as a base64 string or as a PEM string. Only data with an outer SEQUENCE is accepted, which is the rule for all common PKI-related ASN.1 files.

The output is a text file showing the structure of the ASN.1 formatted data. All the bytes in the input are printed in hexadecimal form laid out to show the nested structure of the ASN.1 formatted data together with comments beginning with "--" that give further details about the elements. The length of each object is shown in bytes, for example

30 81 e0  --SEQUENCE/224 bytes

shows the tag (30) and length bytes (81 e0) which begin a SEQUENCE of length 224 bytes, equal to hexadecimal E0 bytes. Use the PKI_ASN1_NOCOMMENTS option to hide the comments: the resulting hexadecimal output without comments should decode back directly to the original binary file.

Example

Dim nRet As Long
Dim strInputFile As String
Dim strOutFile As String

strInputFile = "smallca.cer"
strOutFile = "dumpasn1-smallca.cer.txt"
Debug.Print "File: " & strInputFile
nRet = ASN1_TextDump(strOutFile, strInputFile, 0)
Debug.Print "ASN1_TextDump returns " & nRet
ShowTextFile strOutFile
' Pass input as a string
strInputFile = "MAQwAgUA"
strOutFile = "dumpasn1.txt"
Debug.Print "Input: " & strInputFile
nRet = ASN1_TextDump(strOutFile, strInputFile, 0)
Debug.Print "ASN1_TextDump returns " & nRet
ShowTextFile strOutFile
' Again with no comments
nRet = ASN1_TextDump(strOutFile, strInputFile, PKI_ASN1_NOCOMMENTS)
Debug.Print "ASN1_TextDump returns " & nRet
ShowTextFile strOutFile

File: smallca.cer
ASN1_TextDump returns 0
30 81 e0  --SEQUENCE/224 bytes
   30 81 9a  --SEQUENCE/154 bytes
      02 01  --INTEGER/1 bytes
         01
      30 0d  --SEQUENCE/13 bytes
         06 09  --OBJECTIDENTIFIER/9 bytes
            2a 86 48 86 f7 0d 01 01 05
            --sha1WithRSAEncryption (1.2.840.113549.1.1.5)
         05 00  --NULL/0 bytes
      30 0c  --SEQUENCE/12 bytes
         31 0a  --SET/10 bytes
            30 08  --SEQUENCE/8 bytes
               06 03  --OBJECTIDENTIFIER/3 bytes
                  55 04 03
                  --commonName (2.5.4.3)
               13 01  --PRINTABLESTRING/1 bytes
                  41
                  --'A'
      30 1e  --SEQUENCE/30 bytes
         17 0d  --UTCTIME/13 bytes
            39 39 30 39 31 39 30 31 30 38 34 37 5a
            --'990919010847Z'
         17 0d  --UTCTIME/13 bytes
            33 39 31 32 33 31 32 33 35 39 35 39 5a
            --'391231235959Z'
      30 0c  --SEQUENCE/12 bytes
         31 0a  --SET/10 bytes
            30 08  --SEQUENCE/8 bytes
               06 03  --OBJECTIDENTIFIER/3 bytes
                  55 04 03
                  --commonName (2.5.4.3)
               13 01  --PRINTABLESTRING/1 bytes
                  41
                  --'A'
      30 4a  --SEQUENCE/74 bytes
         30 0d  --SEQUENCE/13 bytes
            06 09  --OBJECTIDENTIFIER/9 bytes
               2a 86 48 86 f7 0d 01 01 01
               --rsaEncryption (1.2.840.113549.1.1.1)
            05 00  --NULL/0 bytes
         03 39  --BITSTRING/57 bytes
            00 --0 unused bits
            --encapsulates:
            30 36  --SEQUENCE/54 bytes
               02 31  --INTEGER/49 bytes
                  02 f9 09 6a 7d 83 55 c2 71 ae f1 6a cb 45 41 ba
                  b3 22 a2 83 b5 ad de 70 e3 37 19 a7 c9 bb ee 76
                  4b e2 fc b8 5c c7 9b e2 3f 27 1f 6f b7 b5 36 80
                  19
               02 01  --INTEGER/1 bytes
                  03
   30 0d  --SEQUENCE/13 bytes
      06 09  --OBJECTIDENTIFIER/9 bytes
         2a 86 48 86 f7 0d 01 01 05
         --sha1WithRSAEncryption (1.2.840.113549.1.1.5)
      05 00  --NULL/0 bytes
   03 32  --BITSTRING/50 bytes
      00 --0 unused bits
      01 9a 9b b2 ec b9 cd fd 66 c6 94 5b 2e d6 96 dc
      32 87 68 da 5e 6f 2e 5d 5a 7f e6 09 2e 60 8f 8c
      45 a5 18 7e 06 1c e9 81 aa ea d6 f2 e3 14 7d 25
      91
--(227 bytes)

Input: MAQwAgUA
ASN1_TextDump returns 0
30 04  --SEQUENCE/4 bytes
   30 02  --SEQUENCE/2 bytes
      05 00  --NULL/0 bytes
--(6 bytes)

ASN1_TextDump returns 0
30 04 
   30 02 
      05 00 

See Also

ASN1_TextDumpToString ASN1_Type

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