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

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Archive for the ‘MIME’ Category

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.

References:

2018

Read the rest of this entry »

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.

--_000_430b30b9ffd74d959b74ab7ba778b487ultrawarenl_
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!

–jeroen

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 https://gist.github.com/anonymous/7233372 and https://gist.github.com/anonymous/7233329
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
n

–jeroen

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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