How to extract pkcs7 envelop contents and verify digital signature?

I want to verify the digital signature of the pkcs7 envelop . PKCS7 e开发者_开发问答nvelop has message content,signer certificate, signature in it. How to extract this parts ? And how to verify digital signature ?

Also I want to check the authenticity of the signer certificate which is a x509 digital certificate .

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If you have the PKCS7 message in an OpenSSL PKCS7 * object, you can simply use PKCS7_verify(). It will verify the signature and the certificate using the supplied trusted certificate store.

If the message is in S/MIME format, the SMIME_read_PKCS7() function can be used to turn it into a PKCS7 * object.