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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘base64’ Category

“No mapping for the Unicode character exists in the target multi-byte code page”

Posted by jpluimers on 2021/06/24

Usually when I see this error [Wayback] “No mapping for the Unicode character exists in the target multi-byte code page” – Google Search, it is in legacy code that uses string buffers where decoding or decompressing data into.

This is almost always wrong no matter what kind of data you use, as it will depend in your string encoding.

I have seen it happen especially in these cases:

  • base64 decoding from string to string (solution: decode from a string stream into a binary stream, then post-process from there)
  • zip or zlib decompress from binary stream to string stream, then reading the string stream (solution: decompress from binary stream to binary stream, then post-process from there)

Most cases I encountered were in Delphi and C code, but surprisingly I also bumped into C# exhibiting this behaviour.

I’m not alone, just see these examples from the above Google search:


Posted in .NET, base64, C, C#, C++, Delphi, Development, Encoding, Software Development, Unicode | Leave a Comment »

Python: saving a web page to a jpeg image file by using the Google base64url encoded screenshot of it

Posted by jpluimers on 2021/02/19

As a follow-up on Still looking for base64url decoding tools, both on-line and for MacOS homebrew: this is in Python, works on MacOS, Linux and Windows, and can be integrated in a web page.

It is based on the ideas in [WayBack] Python-Twitter-Hacks/ at master · edent/Python-Twitter-Hacks · GitHub, which was more like a code snippet with hard coded literals.

It downloads a jpeg web-site screenshot using the Google PageSpeed API V1, which generates the screenshot as a base64url encoded blob inside a JSON structure.

Python does not have native Python base64url support, but the concept of it is fairly straightforward: [WayBack] RFC 4648 – The Base16, Base32, and Base64 Data Encodings: Base 64 Encoding with URL and Filename Safe Alphabet, which allows data to be passed inside URLs without reverting to [WayBack] Percent-encoding – Wikipedia.

My changes work, but are by no means in canonical form or Idiomatic Python. I have a long way to go to reach that level of Python.

So I forked the repository, and fixed the script basing it on Python 3.

I might make it V2 compatible in the future. More information on V2 in [WayBack] Google APIs Explorer: Services > PageSpeed Insights API v2 > pagespeedonline.pagespeedapi.runpagespeed

Content is in the below gist.


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Posted in base64, base64url, Development, Encoding, Python, Scripting, Software Development | Leave a Comment »

Common SMTP message size limits

Posted by jpluimers on 2020/04/08

After a 2018 discussion with a “zorgkantoor” (Dutch for office that arranges for special long term health care needs, successor of AWBZ) about their very low (10 megabyte) SMTP message size limit – even though they expect scanned PDF documents.

Their web-care team posed this limit as normal, so I made a list of limits in their peer group, common world-wide and well-ranked Dutch internet providers.

My plan is to check the progression of these limits over time.

Note these are the bruto message sizes including encoded attachments. Since encoding in [WayBack] MIME Base64 – Wikipedia has a overhead of at least 37% (encoded size is at least 1.37 the original size), the unencoded maximum size is less than 73% of what is listed below.



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Posted in base64, Communications Development, Development, eMail, Encoding, Internet protocol suite, MIME, Power User, Python, Scripting, SMTP, SocialMedia, Software Development, TCP | Leave a Comment »

It looks like gmail finally understands Outlook Calendar entries

Posted by jpluimers on 2018/11/12

For a very long time, gMail did nothing with Outlook Calendar entires.

So I had to view at the message source, then translate them to Google Calendar entries myself.

Content-Type: text/calendar; charset="utf-8"; method=REQUEST
Content-Transfer-Encoding: base64


As of late, they seem to be processed into Google Calendar compatible entries. Nice!


Posted in base64, Development, Encoding, GMail, Google, GoogleCalendar, MIME, Office, Outlook, Power User, Software Development, UTF-8, UTF8 | Leave a Comment »

Some command-line tips for OpenSSL and file format (pfx, p12, cer, crt, key, etc.) conversion of certificates, keys

Posted by jpluimers on 2015/02/27

OpenSSL is really nice, but remembering all these command-line switches is difficult, especially when you do not use them often enough.

I don’t, and when I do there are a few common tasks I perform, and I was glad to find a few links with great information:

I’ve converted them to batch files that run fine when copied to the directory where you put the x86 or x64 Windows version of OpenSSL (they assume %~dp0openssl.exe for the location of the OpenSSL.exe binary, just in case it is not on the path, or you have various tools that scattered around incompatible copies of OpenSSL binaries).

OpenSSL defaults to PEM format (that has text base64 strings), so if you get DER format (binary) you need to convert them.

A few errors I got and what they mean

Error decrypting PKCS#7 structure

Error decrypting PKCS#7 structure
5216:error:21070073:PKCS7 routines:PKCS7_dataDecode:no recipient matches certificate:.\crypto\pkcs7\pk7_doit.c:538:
5216:error:21072077:PKCS7 routines:PKCS7_decrypt:decrypt error:.\crypto\pkcs7\pk7_smime.c:557:

This error means that the recipient of the email does not match the certificate you pass in. What happens is that OpenSSL tries to decrypt the mail, it cannot match the certificate to the mail, and barfs. It usually happens when you have From/To reversed by accident.

Error decrypting PKCS#7 structure

Error decrypting PKCS#7 structure
4948:error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch:.\crypto\x509\x509_cmp.c:330:
4948:error:2107207F:PKCS7 routines:PKCS7_decrypt:private key does not match certificate:.\crypto\pkcs7\pk7_smime.c:552:

This means somewhere you mixed up a private and public key in the certificate files.

Use something like the OpenSSL wrapper verify-private-key-matches-certificate-x509-pem-cer.bat to verify them.

Error reading S/MIME message

Error reading S/MIME message
6900:error:0D06B08E:asn1 encoding routines:ASN1_D2I_READ_BIO:not enough data:.\crypto\asn1\a_d2i_fp.c:251:
6900:error:0D0D106E:asn1 encoding routines:B64_READ_ASN1:decode error:.\crypto\asn1\asn_mime.c:193:
6900:error:0D0D40CB:asn1 encoding routines:SMIME_read_ASN1:asn1 parse error:.\crypto\asn1\asn_mime.c:528:

OpenSSL does not like .EML files to end with a period (. which SMTP needs to process when sending an .EML file).
See and
The former throws this error, the latter not. This is not caused the width of the base64 encoding (not yet archived at the WayBack machine), which I initially thought, but the terminating period.

Verification failure

Verification failure
8228:error:21075075:PKCS7 routines:PKCS7_verify:certificate verify error:.\crypto\pkcs7\pk7_smime.c:342:Verify error:self signed certificate in certificate chai


Posted in base64, Development, Encoding, MIME, OpenSSL, Power User, Security, Software Development, Windows, Windows 7, Windows 8, Windows Server 2000, Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows XP | Leave a Comment »

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