iOS: wrong cert format makes app crash during request

[silkimen]

Enabling SSL pinning does not fail when certificates in wrong format (e.g. PEM encoded one) are used on iOS. But later on the app crashes when you try to send a request.

[kevto]

We're experiencing the same issue. The app throws an "uncaught exception": *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'

[kevto]

For anyone who runs into this issue, according to the plugin's documentation it is indeed required to have the .cer files encoded with DER.

To make validate if the .cer file is encoded with DER:
openssl x509 -in <your_file.cer> -inform der -text -noout
If it throws an error like:

unable to load certificate
13978:error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1306:
13978:error:0D07803A:asn1 encoding routines:ASN1_ITEM_EX_D2I:nested asn1 error:tasn_dec.c:380:Type=X509

Then you know your .cer file is not encoded with DER. To transform the PEM encoded file to DER, use:
openssl x509 -in <input.cer> -outform der -out <output.cer>

Source: https://info.ssl.com/article.aspx?id=12149