How to create and read pkcs7 signed envelop with smime format?

I want to create pkcs7 signed envelop having S/MIME format and also want to read it. The file extensi开发者_运维技巧on is pk7.

How to do it with the OpenSSL library?

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The SMIME_read_PKCS7() and SMIME_write_PKCS7() functions can be used to convert an SMIME message into a PKCS7 structure and vice-versa.

You can use PKCS7_sign() / PKCS7_encrypt() to create PKCS7 structures, and PKCS7_verify() / PKCS7_decrypt() to consume them.